{
  "id": "hydroxychloroquine",
  "title": "Hydroxychloroquine",
  "lang": "en",
  "source_lang": "en",
  "summary": "Hydroxychloroquine is a quinoline drug used against malaria and as an immunomodulator in lupus and rheumatoid arthritis.",
  "category": "health",
  "subcategory": "drugs",
  "type": "concept",
  "aliases": [
    "Plaquenil",
    "HCQ",
    "硫酸羟氯喹"
  ],
  "generated_at": "2026-10-16",
  "model": "pro/claude-haiku-5-5",
  "url": "https://aiwiki.page/en/hydroxychloroquine/",
  "translations": {
    "zh-Hans": {
      "url": "https://aiwiki.page/zh/hydroxychloroquine/",
      "json": "https://aiwiki.page/zh/hydroxychloroquine.json"
    }
  },
  "sections": [
    {
      "heading": "",
      "text": "Hydroxychloroquine (HCQ) is a quinoline-class drug that was developed against malaria and later became central to the treatment of autoimmune disease. It is a hydroxy-analog of chloroquine that is better tolerated. Its clinical story began with wartime antimalarial use, when a serendipitous consequence of the mass use of antimalarials during World War II was the discovery that they could be used to treat inflammatory arthritis and lupus. Hydroxychloroquine is now the most commonly prescribed antimalarial for treatment of autoimmune disease.\n\nThe drug matters for two reasons. It remains an antiparasitic agent for malaria treatment and prevention, and it is a long-term immunomodulatory therapy for conditions such as systemic lupus. It is considered the first-line treatment for systemic lupus erythematosus. Its benefits in lupus also extend to outcomes: patients with systemic lupus erythematosus treated with hydroxychloroquine have lower mortality rates and a lower risk of lupus nephritis. Its public profile changed sharply in 2020, when it was tested and promoted against COVID-19; the FDA said the drugs were unlikely to be effective for COVID-19 in the authorized uses, and that because of serious cardiac events and other side effects, the potential benefits no longer outweighed the risks.\n\nThis entry covers the drug's chemistry and pharmacology, its mechanisms of action, its history, its established and investigational uses, dosing and monitoring, adverse effects, the COVID-19 episode and regulatory decisions, access and regulation, and the questions that remain open."
    },
    {
      "heading": "Chemical identity and pharmacokinetics",
      "text": "Structure, salt form and formulation\n\nHydroxychloroquine (HCQ) is built on a chemical 4-aminoquinoline scaffold, a 7-chloroquinoline ring linked at position 4 to a pentyl-chain amine. What separates it from chloroquine is the terminal nitrogen of that chain: it carries an ethyl group and a 2-hydroxyethyl arm, so the side chain ends in an alcohol group where chloroquine has a second ethyl group. The systematic name of the sulfate salt reflects this, with the quinoline bearing an N-ethyl-N-(β-hydroxyethyl)amino group on a 1-methylbutylamino chain. The free base is C18H26ClN3O, and the sulfate salt is C18 H26 ClN3 O.H2 SO4 with a molecular weight of 433.95. Subtracting the sulfuric acid gives a free-base mass of about 335.9 g/mol, a figure calculated here rather than taken from a source.\n\nThe commercial product is the sulfate. It is a white or practically white, crystalline powder, freely soluble in water. Oral tablets are dosed on the salt, and each 200 mg tablet is equivalent to 155 mg of base, a distinction that matters when converting between labelled and active doses.\n\nStereochemistry\n\nHCQ has a single stereogenic centre, at the carbon of the pentyl chain that bears the methyl group. The marketed drug is racemic: the chemical name is written as (RS), indicating equal amounts of the R and S enantiomers. The two enantiomers are not interchangeable in every respect. In vitro work has reported that the racemic compound and its R and S enantiomers show different activities against SARS-CoV-2, although whether those differences translate into clinical advantage is not established. Pharmacokinetic data point the other way for absorption: bioavailability of the enantiomers was not statistically different. Whether the enantiomers differ in retinal or cardiac toxicity remains an open question, which is why stereochemistry is treated as a research topic rather than a settled explanation of the drug's risk profile.\n\nWeak base and cellular accumulation\n\nHCQ is a weak base with two ionisable nitrogen centres. In neutral extracellular fluid a portion of the molecule is uncharged and can cross membranes. Once inside acidic compartments such as lysosomes, endosomes or the parasite's food vacuole, the molecule becomes protonated and is retained, a process known as ion trapping. The same behaviour is thought to explain the very large volume of distribution and the long half-life, since the large volume of distribution and the long half-life of HCQ are likely to be related to its accumulation in eukaryotic cell acidic compartments.\n\nAbsorption and tissue distribution\n\nAfter oral dosing, absorption is fast and extensive. Gastrointestinal absorption is fast and blood concentration peaks two to three hours after a single dose, and the mean fraction of the dose absorbed is 0.74. Bioavailability values from different sources vary, with one review placing it at 70%–80%. Food influences uptake: the recommended practice is dosing on a full stomach with a full glass of water or milk, and very severe malnutrition such as in patients with kwashiorkor can inhibit absorption.\n\nDistribution is the defining feature of the drug's kinetics. Intravenous data give a half-life and mean residence time of around 40 days, with volumes of distribution of 5,522 l from blood and 44,257 l from plasma. The drug binds avidly to tissues, especially melanin-containing tissues, which underlies its retinal accumulation (see melanin binding in the retinal pigment epithelium). Within blood, uptake is greatest in mononuclear cells and is not detectable in polymorphonuclear cells, placing the drug in close contact with lymphocytes and macrophages. Animal data suggest high concentrations in the lungs, kidney, liver and spleen, and lung-to-plasma ratios ranging from 27 to 177 were reported in macaques, though the authors caution that human ratios may be lower.\n\nProtein binding, metabolism and elimination\n\nReported plasma protein binding varies by source, from about 50% measured in vitro to a figure of 63% in another protocol. Metabolism occurs largely in the liver, where CYP enzymes catalyze the dealkylation of HCQ to pharmacologically active metabolites. The main metabolite is desethylhydroxychloroquine (DHCQ). Renal clearance of unchanged drug is modest: renal clearance of unchanged hydroxychloroquine has been shown to account for only 21% of the administered dose.\n\nThe terminal half-life is long, and reported values depend on the matrix measured. The terminal half-life ranged from 40 to 50 days, and a single-dose estimate in whole blood was 50 +/- 16 days. Plasma estimates can be far longer, which is one reason whole blood is preferred for pharmacokinetic work: it is preferable to measure whole blood concentrations of hydroxychloroquine, rather than plasma concentrations. The persistence of the drug is attributed to tissue sequestration rather than slow clearance, since the persistence of hydroxychloroquine in the body is due primarily to this extensive tissue distribution, rather than to low clearance.\n\nFor practical purposes, the long half-life means that steady-state concentrations are reached only after many weeks of daily dosing, and drug remains detectable for months after discontinuation. This accumulation is central to how dose and duration relate to toxicity, a topic covered in the sections on adverse effects and dosing."
    },
    {
      "heading": "Mechanism of action",
      "text": "Antimalarial action\n\nHydroxychloroquine (HCQ) is a lipophilic weak base. Its membrane permeability lets it gather inside acidic intracellular compartments, including the lysosomes and the food vacuoles of the malaria parasite, where it raises the local pH The antimalarial action of HCQ is dependent on its lipophilicity to permeate and accumulate in intracellular structures, including lysosomes and food vacuoles of the malaria parasite. Once inside an intracellular vesicle, HCQ increases the pH as a weak base. Most of the detailed work on this step has been done with the parent compound, chloroquine, which diffuses down the pH gradient to accumulate about a 1000-fold in the acidic vacuole of the parasite.\n\nThe target is the parasite's handling of haemoglobin. As the parasite digests host haemoglobin, it releases free heme, which is toxic. The parasite normally neutralises it by crystallising it into inert hemozoin (β-hematin). Quinoline drugs are thought to interfere with this step. In one rodent model, chloroquine reduces by 80 percent the activity of this enzyme, without inhibiting release of FP from hemoglobin, which leaves excess unpolymerised heme in the parasite. Other reports describe the same consequence in general terms: when polymerisation is blocked, its increased concentration in the parasites food vacuole will cause oxidative damage to membranes and death of the parasite. The two accounts disagree on whether haemoglobin breakdown itself is affected, and a 2023 in vitro study found that chloroquine does not completely halt the transformation process but rather slows it down. The precise molecular mechanism is therefore still debated.\n\nImmunomodulatory mechanisms\n\nIn antigen-presenting cells, the same pH shift is thought to block the normal handling of self-antigens. HCQ increases the pH of lysosomes and inhibits lysosomal proteases, thereby inhibiting antigen processing and presentation to major histocompatibility complex class-II proteins (MHC-II). Within the late endosome, it inhibits the clipping and replacement of the invariant chain (Ii) by antigenic peptides, which prevents MHC-II from presenting antigen to CD4+ T cells.\n\nEndosomal Toll-like receptors (TLRs) form a second, widely cited pathway. In plasmacytoid dendritic cells, HCQ inhibits immune complex-mediated Toll-like receptor (TLR) 7 and 9 in the endosome, which reduces downstream production of type I interferons. The exact way this happens is contested. One line of work argues that the drugs interact with nucleic acid ligands rather than acting only through endosomal acidification. A separate study reported that HCQ's effects on TLR9 did not require endo-lysosomal pH change, nor impaired autophagosome-lysosome fusion.\n\nBeyond antigen presentation and TLR signalling, HCQ has been reported to dampen cytokine output and lymphocyte expansion. Studies in lupus describe effects on IL-1, IL-6, IL-17, IL-22, and TNF-α, and HCQ can inhibit the proliferation of T cells and B cells. These findings come largely from cell culture and animal work, and their weight in patients is not established.\n\nAntiphospholipid-related effects\n\nIn antiphospholipid syndrome (APS), HCQ is thought to work through several effects at once. Reviews describe its ability to bind sialic acid present in cell membranes, its capacity to block the binding of antiphospholipid antibodies to the cell and the induced increase of pH in extracellular and intracellular compartments. The most specific evidence concerns the antibody–protein complex. In laboratory assays, HCQ reduces the formation of aPL-beta2GPI complexes to phospholipid bilayers and cells. The authors of one study proposed that this appears to be due to reversible interactions between HCQ and the proteins, because the inhibition was reversed after dialysis against buffer. A later study on the individual enantiomers suggested that the S-form binds β2-glycoprotein I more strongly than the R-form (see enantiomers for the general concept).\n\nHCQ may also act on the downstream thrombotic cascade. Antibodies in APS interfere with anticoagulant pathways and promote a prothrombotic state, and HCQ has been reported to inhibit complement activation, reduce production of tissue factor (TF). In a mouse model, HCQ significantly diminish both thrombus size and thrombus duration in mice that were previously injected with IgG-APS. The clinical relevance of these laboratory findings is discussed in the APS section of this entry, where the drug is used for refractory obstetric APS.\n\nGaps between established and proposed mechanisms\n\nThe antimalarial mechanism is the best supported of these, but even it is not fully resolved. For the rheumatic indications, a 2020s review notes that the exact mechanism of action of HCQ in the treatment of rheumatic diseases is not fully understood. The immunological effects are a collection of proposed pathways rather than one confirmed target, and several were first described in cell lines or mice. The mechanisms also differ by indication: lysosomal and TLR effects are central in lupus, while binding of antiphospholipid complexes matters more in APS. Results from one setting cannot be transferred directly to another without further study. Work on TLR biology and on the hemozoin pathway continues, and the field remains open on how far each mechanism contributes to clinical benefit in patients."
    },
    {
      "heading": "Discovery and early history",
      "text": "Hydroxychloroquine grew out of the search for better antimalarials in the years around the Second World War. Chloroquine is an antimalarial drug that was developed in 1934. The compound was later rediscovered, and it was given the name 'chloroquine' by E. K. Marshall in 1945. The earlier drug, quinacrine (Atabrine), produced numerous side effects, prompting researchers to develop derivate compounds. Its toxicity was not the only drawback: it had numerous side effects including yellowing of the skin.\n\nThe hydroxylated analogue was reported by Alexander Surrey and Henry Hammer, chemists at the Sterling–Winthrop Research Institute in Rensselaer, New York. They published a synthesis of hydroxychloroquine in 1950. Dates in the secondary literature are not uniform. Some sources place the synthesis in 1946, when the reasoning was that introducing a hydroxy group into one of the N-ethyl groups of chloroquine phosphate should significantly reduce chloroquine toxicity. Others date the discovery to 1949, and the patent rights are associated with a 1950 or 1951 grant. These discrepancies should be checked against the original papers and patent records.\n\nDuring the war, malaria was a major threat to Allied troops. Malaria was a leading cause of death among soldiers, particularly in the South Pacific. Their production was industrialized during the war, and aggressive research efforts to develop an alternative led to field testing of one of its derivative compounds, chloroquine, by the US Army in 1943. The large-scale use of these drugs produced an unplanned finding. A serendipitous consequence of the mass use of antimalarials during World War II was the discovery that they could be used to treat inflammatory arthritis and lupus.\n\nThe first clinical reports on these compounds in lupus came from quinacrine rather than chloroquine. Francis Page's 1951 report described 18 patients with lupus erythematosus treated with quinacrine, including one with acute systemic lupus erythematosus. He reported good to excellent results in 17. Chloroquine followed. Goldman and co-workers (1953) thought chloroquine (Aralen) was of value in systemic and discoid lupus erythematosus. It was less toxic than quinacrine and better tolerated by patients. In rheumatoid arthritis, the use of antimalarial drugs became increasingly popular after Bagnall published in 1957 the results of a 4-year study in which he obtained a \"good\" result in some 70% of the cases. The first warnings of hazards from this therapy began to appear soon afterwards. Chloroquine retinopathy in particular became a concern, which shaped later prescribing.\n\nThe move toward hydroxychloroquine was driven largely by tolerability. In animal studies, it was demonstrated to be much less (~40%) toxic than CQ. Today HCQ is currently preferred over chloroquine as it has a better safety profile, especially regarding the risk of retinopathy.\n\nRegulatory history is also worth separating by indication. The USFDA first approved HCQ on 18 April 1955 for the treatment of malaria. The rheumatic indications came later and are reported inconsistently. One patient-oriented resource states that in 1955 HCQ was shown to be effective for both systemic lupus and rheumatoid arthritis, and that in 1956, the U.S. Food and Drug Administration approved HCQ for symptoms of lupus and rheumatoid arthritis. The current US labelling lists treatment of rheumatoid arthritis in adults, treatment of systemic lupus erythematosus in adults, and treatment of chronic discoid lupus erythematosus in adults. Early use was restricted: HCQ was previously prescribed only for people whose lupus disease activity was mild in its course, but today HCQ is recommended for most individuals with lupus, whether mild, moderate, or severe, as well as during pregnancy and while breastfeeding."
    },
    {
      "heading": "Antimalarial use",
      "text": "Hydroxychloroquine (HCQ) was developed as an antimalarial and remains licensed for both treating and preventing malaria in several countries. Its role has narrowed as parasite resistance has spread and other drugs have become preferred, so current use depends on the infecting malaria species, local drug sensitivity, and whether the patient is being treated or protected before travel.\n\nTreatment of uncomplicated malaria\n\nUS labelling lists HCQ for uncomplicated infections caused by Plasmodium falciparum, P. malariae, P. ovale and P. vivax. The standard adult course is 800 mg of the sulfate salt (620 mg base), followed by 400 mg at 6, 24 and 48 hours, for a total of 2,000 mg salt. A weight-based version starts at 13 mg/kg salt (capped at 800 mg) and continues at 6.5 mg/kg (capped at 400 mg). The whole course is therefore finished within two days, which is the basis for describing it as a short, multi-dose regimen.\n\nFor P. vivax and P. ovale, the regimen does not clear the dormant liver stages on its own. Treatment is paired with an 8-aminoquinoline such as primaquine, and G6PD deficiency should be excluded by testing first. Species-specific cautions are also recorded in clinical references: confirmation of single-species infection is advised before using HCQ for P. malariae or P. knowlesi, and P. knowlesi infection can progress quickly enough to justify hospital or close monitoring.\n\nHCQ is not used for severe malaria. Clinical references also advise against its use where chloroquine resistance is expected, and it is not effective against chloroquine-resistant or HCQ-resistant Plasmodium strains. In those cases, WHO guidance favours artemisinin-based combination therapies (ACTs) for falciparum malaria, while chloroquine-susceptible non-falciparum infections may be treated with either an ACT or chloroquine. Under US treatment guidance, HCQ is generally listed as a second-line alternative to chloroquine across several regimens.\n\nChemoprophylaxis for travellers\n\nFor adults travelling to endemic areas, the usual prophylactic dose is 400 mg salt (310 mg base) once weekly, taken on the same day each week. Children receive 6.5 mg/kg salt weekly, capped at the adult dose. Start timing differs slightly between sources: the US label advises beginning two weeks before exposure, whereas CDC travel guidance says one to two weeks before travel. In both cases, weekly dosing continues throughout the stay and for four weeks after leaving the malarious area.\n\nProphylactic use is restricted to places where chloroquine resistance has not been reported. CDC travel recommendations describe HCQ as an alternative to chloroquine that may be better tolerated, and Canadian guidance lists it as an option only where the parasites are considered susceptible, placing atovaquone-proguanil ahead of it in those settings.\n\nLimits and remaining gaps\n\nThe main constraint is resistance: where chloroquine-resistant parasites circulate, HCQ offers little protection or cure, so prescribers depend on current regional surveillance. A further limitation concerns special populations. Pharmacokinetic modelling studies note that detailed dose-adjustment guidance for pregnant women, children and patients with reduced renal function is still lacking, and that drug accumulation in renal impairment may increase the risk of adverse effects.\n\nPosition in guidelines\n\nThe WHO malaria guideline, most recently updated in 2025, names ACTs and chloroquine in its treatment recommendations, and HCQ appears mainly as an alternative to chloroquine in secondary summaries rather than as a headline recommendation. National documents differ in emphasis: US and Canadian guidance both include HCQ as a listed option, but with the conditions on species, resistance and travel setting described above. Local national guidelines should be consulted, as recommendations are revised as resistance patterns change."
    },
    {
      "heading": "Rheumatic and autoimmune indications",
      "text": "Systemic lupus erythematosus\n\nStandard references place hydroxychloroquine at the front of treatment for systemic lupus erythematosus (SLE), describing it as the first-line option. Its role has widened over time. Earlier practice limited it largely to patients with mild disease, reserving corticosteroids or immunosuppressants for active flares. Current guidance extends its use to most individuals with lupus, whether mild, moderate, or severe, as well as during pregnancy and while breastfeeding.\n\nThe survival evidence is largely observational. Analyses of the multiethnic LUMINA cohort returned a propensity-adjusted odds ratio of 0.32 for survival among users (an odds ratio after propensity score adjustment of 0.32 (95% CI 0.12–0.86)). A 2022 meta-analysis that pooled cohort studies produced a hazard ratio of 0.46 for overall mortality (pooled HR 0.46, 95% CI 0.38–0.57). Randomised data are more modest. A systematic review of trials found lower corticosteroid needs in three studies, while the effect on severe flares was reduced only with borderline significance.\n\nKidney outcomes follow a similar pattern. LUMINA data linked use to a lower frequency of World Health Organization class IV glomerulonephritis. A more recent retrospective cohort of biopsy-proven lupus nephritis reported 59% and 66% lower risk of sustained eGFR decline of ≥30% and ≥40% with time-varying exposure. In pregnancy, a 257-patient cohort found that higher risk of flare if hydroxychloroquine stopped.\n\nDiscoid and cutaneous lupus\n\nChronic discoid lupus is one of the drug's approved US indications. The label covers treatment of chronic discoid lupus erythematosus in adults, at 200 mg or 400 mg once daily (or in two divided doses). Paediatric use for this indication lacks an established safety and efficacy basis in the label. Dates differ by source: the label gives Initial U.S. Approval: 1955, whereas a patient-education resource states that the FDA approved it in 1956 for lupus and rheumatoid arthritis symptoms.\n\nThe clinical rationale predates the modern drug. Quinine was first used to treat cutaneous lupus in 1834, and subsequent reports in 1928 and 1938 showed good results with another quinine-like drug in discoid and subacute cutaneous lupus. The US label also covers dermatological conditions caused or aggravated by sunlight in adults, which is relevant because photosensitive skin disease is a common feature of cutaneous lupus.\n\nRheumatoid arthritis and primary Sjögren's syndrome\n\nIn rheumatoid arthritis (RA), the drug is labelled for adults, with an initial dose of 400 mg to 600 mg daily. Its effect builds slowly, since the action of hydroxychloroquine is cumulative and may require weeks to months to reach its maximum. It is therefore used as a disease-modifying agent rather than for rapid symptom relief.\n\nThe evidence in primary Sjögren's syndrome is weaker. The JOQUER trial randomised 120 patients with primary Sjögren syndrome to receive hydroxychloroquine (400 mg/d) or placebo until week 24. The proportion meeting the primary end point was 17.9% (10/56) in the hydroxychloroquine group and 17.2% (11/64) in the placebo group, and the authors concluded that the drug did not improve symptoms over that period. The same trial showed a biological effect: treatment for 24 weeks with HCQ significantly reduced type I IFN scores and ISG-expression compared with the placebo-treated group. A later head-to-head trial reported that IGU monotherapy was more effective than HCQ in improving composite, systemic and serological measures in active pSS patients.\n\nSteroid-sparing effects and immunosuppressant burden\n\nThe most consistent secondary benefit is a reduction in glucocorticoid exposure. Reviews note that HCQ can decrease the long-term need for glucocorticoids (GCs), and pregnancy studies describe the same effect, with the drug steroid sparing. Because long-term corticosteroid use carries cumulative toxicity, this effect is the main basis for the claim that the drug reduces the burden of other immunosuppressive treatment. Direct comparative data on that broader claim are limited, and the evidence for it rests mostly on the glucocorticoid-sparing observations above.\n\nPorphyria cutanea tarda and Q fever\n\nBeyond lupus and arthritis, the drug is listed among recognised uses for porphyria cutanea tarda, and certain infections such as Q fever and certain types of malaria. In porphyria cutanea tarda, low-dose regimens are typically used in patients who cannot tolerate phlebotomy, the standard first-line approach. In Q fever, the drug is used against the chronic form of the infection, usually alongside another antibiotic. These are more specialised indications, and their evidence base is smaller than that for SLE."
    },
    {
      "heading": "Other clinical and investigational uses",
      "text": "Antiphospholipid syndrome\n\nHydroxychloroquine (HCQ) has been studied in antiphospholipid syndrome (APS), an autoimmune condition in which thrombosis or pregnancy morbidity occurs alongside persistently positive antiphospholipid antibodies. Around 20–30% of pregnant women with APS have adverse outcomes despite treatment with aspirin and heparin, a group described as refractory obstetric APS. In this setting, HCQ has shown positive effects added to standard care in some patients. Proposed actions include binding sialic acid on cell membranes, blocking antibodies from attaching to cells, and raising pH in extracellular and intracellular compartments. The precise mechanisms in refractory APS still need to be fully clarified.\n\nThe clinical evidence is mostly observational. A European multicentre retrospective study reported that, among 14 patients with previous refractory obstetrical APS, the addition of hydroxychloroquine resulted in live-born babies in 11/14 (78%). A single-centre cohort comparing pregnancies with and without HCQ found higher live-birth rates with the drug, but its authors stated that the addition of HCQ to classical treatment may present a promising approach that needs to be confirmed with prospective studies. A later meta-analysis judged that the effectiveness of HCQ in reducing APS complications during pregnancy is still not well-established. A randomized trial in primary APS, which compares HCQ added to conventional treatment with conventional treatment alone, is registered on ClinicalTrials.gov.\n\nMetabolic effects in lupus and rheumatoid arthritis\n\nBecause inflammatory arthritis and lupus raise cardiovascular risk, HCQ's effects on lipids and glucose have attracted interest. In a retrospective cohort of 1261 patients with rheumatoid arthritis, patients taking HCQ at baseline had significantly lower total cholesterol, low-density lipoprotein, and triglycerides, with higher high-density lipoprotein, yet fasting plasma glucose levels were not significantly associated with HCQ exposure. A small randomized study of 30 patients, mostly with rheumatoid arthritis, found that total cholesterol decreased from 5.4 mmol/L to 5.1 mmol/L after four weeks of treatment, but those levels remained unchanged after eight weeks. Glucose findings are less consistent: results regarding glucose metabolism and insulin resistance after initiation of HCQ in patients with RA have been conflicting. Evidence on diabetes incidence is also limited, and researchers have noted that it is particularly important to conduct larger population studies with long follow-up times.\n\nPaediatric use\n\nRegulatory status differs by indication. For malaria, the safety and effectiveness of hydroxychloroquine sulfate have been established in pediatric patients for the treatment of uncomplicated malaria, and the drug's use in children is described as not raising pediatric-specific problems for malaria. Dosing has a weight threshold: use is not recommended in children weighing less than 31 kilograms for Plaquenil tablets. For lupus and arthritis, the safety and effectiveness of hydroxychloroquine sulfate have not been established in pediatric patients for the treatment of rheumatoid arthritis, chronic discoid lupus erythematosus, or systemic lupus erythematosus. Some summaries are less restrictive: a trial protocol describes the drug as approved for these indications in adults and children by FDA and EMA, which conflicts with the US labelling, so the current prescribing information in each market should be checked. Paediatric lupus use therefore rests largely on off-label practice and small studies, such as a randomized trial in children with proliferative lupus nephritis published in 2023.\n\nExploratory research in cardiovascular disease, cancer and infection\n\nBeyond its established roles, HCQ has been investigated in cardiovascular disease, cancer and infection. Much of this work rests on plausible mechanisms and observational associations. For example, the suggestion that HCQ lowers cardiovascular risk through glycaemic control comes largely from patients with rheumatoid arthritis and lupus, and researchers have argued that studies that have focused on the efficacy of hydroxychloroquine on blood glucose and diabetes risk in patients with rheumatism have proven inadequate. Antitumour and antiviral activity has been explored mainly in laboratory and early clinical settings. The antiviral claims were tested in COVID-19, where randomized trials did not confirm benefit (see covid-19). Results from observational data and laboratory models do not establish efficacy in these fields, and only randomized trials can settle questions of benefit."
    },
    {
      "heading": "Dosing, monitoring and administration",
      "text": "For lupus and rheumatoid arthritis, the usual oral dose is 200 to 400 mg a day, often taken once or twice daily with food or milk. Tablets are 200 mg of the sulfate salt, which corresponds to about 155 mg of base. Newly diagnosed lupus patients are often started on 400 mg once daily for several weeks so that blood levels can build up, and then move to a maintenance dose of 200 to 400 mg daily. Guidance for autoimmune conditions is usually written in daily doses, while malaria prophylaxis and treatment follow short, fixed schedules.\n\nWeight-based limits\n\nSince the 2010s, the main dosing principle has been a ceiling expressed per kilogram of actual body weight. The earlier American Academy of Ophthalmology (AAO) guidance set the limit at 6.5 mg/kg of ideal body weight. The 2016 revision lowered it to 5 mg/kg of actual body weight per day, which is the basis of most current rheumatology and ophthalmology advice. Because many patients were prescribed a flat 400 mg daily, this change meant that lighter patients (roughly under 80 kg) often needed lower doses. A 60 kg adult would have a ceiling of about 300 mg a day. Some observational data, including a retrospective single-centre study and a case-crossover analysis of hospitalizations, have linked doses at or below 5 mg/kg to more flares. That association is not a randomized result, so it is weighed against the retinal risk rather than used to justify exceeding the ceiling. Some clinicians have proposed measuring whole-blood drug levels to guide dosing, but this approach has not been adopted into standard guidelines. Pediatric lupus and arthritis dosing is also weight-based, typically in the range of 2 to 6 mg/kg a day, with many experts recommending a cap of 5 mg/kg. Practitioners often adjust for low body weight or reduced kidney function by using alternate-day dosing or splitting tablets.\n\nMalaria schedules\n\nTreatment of uncomplicated malaria uses a short, multi-dose course: an initial 800 mg (620 mg base), followed by 400 mg (310 mg base) at 6, 24 and 48 hours. Prophylaxis is given once a week on the same day, at 400 mg salt (310 mg base) for adults. In children it is 6.5 mg/kg of salt (5 mg/kg of base), capped at the adult dose. Prophylaxis begins one to two weeks before travel and continues weekly while in the endemic area, then for four weeks after departure. The manufacturer does not recommend the tablets for children under 31 kg. Weekly regimens are favoured partly because adherence has been found to be higher than with daily dosing in military studies.\n\nRetinal screening\n\nThe retinal toxicity risk depends on the daily dose and duration of use. At doses below 5 mg/kg, the risk within five years is generally below 1%, and below 2% after ten years, but it increases sharply as doses approach 6 mg/kg. Cumulative dose is not considered a reliable predictor because patients take different amounts depending on weight. The AAO's current recommendations (2025 revision, approved by the board in October 2025) advise a full baseline examination soon after treatment begins, using optical coherence tomography (OCT) and fundus autofluorescence (FAF) to rule out pre-existing disease and provide a comparison point. Routine annual screening may be deferred during the first five years if no significant risk factors are present, but it should begin at the start of treatment if risk factors exist. These include doses above 5 mg/kg, chronic kidney disease, concurrent tamoxifen, pre-existing macular disease and older age. Visual fields and multifocal tests are used as secondary confirmation. Adherence to these guidelines has been uneven; a 2017 survey found that few rheumatologists and ophthalmologists knew the recommended schedule.\n\nAdherence, pregnancy and long-term therapy\n\nBenefit depends on continuous use, and interruptions are associated with flares in lupus. Patients are therefore encouraged to keep taking the drug through pregnancy, when it is generally continued because stopping it raises the risk of disease activity. Long-term therapy requires periodic review of dose against current weight, kidney function, and retinal findings, as well as adjustment when weight or renal status changes. Staying within the weight-based limit over decades is the main safeguard against late-onset toxicity, which is why the prescribing and monitoring routine is treated as an integral part of treatment."
    },
    {
      "heading": "Adverse effects, toxicity and interactions",
      "text": "Retinopathy\n\nRetinopathy is the best-known long-term toxicity of hydroxychloroquine. It is linked mainly to cumulative exposure rather than to any single dose. Toxicity reflects damage to the retinal pigment epithelium and the photoreceptors of the macula, and it typically appears as a bull's-eye maculopathy or pericentral ring scotomas. One review of SLE patients reported that the risk rises when the cumulative dose exceeds about 1000 g, when the daily dose exceeds 5 mg/kg of real body weight (roughly fourfold higher risk), and when treatment runs longer than about ten years, with an estimated 3.9% risk at ten years and 11.3% at fifteen. Renal impairment, concurrent tamoxifen, and starting therapy at an older age also raise the risk. Early retinal damage may continue after the drug is stopped, which is why screening is emphasised. Earlier estimates varied: a 2003 study of 526 patients found an incidence of 0.38%, and a 2010 study of patients treated for five to seven years found up to 0.68%.\n\nScreening guidance from the American Academy of Ophthalmology (2016 revision) recommends a baseline examination within the first year of treatment and annual examinations after five years for patients on doses of 5 mg/kg/day or less without major risk factors. Optical coherence tomography and wide-field fundus autofluorescence are the primary tests, with visual fields and multifocal electroretinography serving as secondary confirmation. Uptake of screening has been uneven: a Korean study reported that annual retinal screening among new users rose from 3.5% in 2006 to 22.5% in 2019.\n\nCardiac effects\n\nHydroxychloroquine can prolong the QT interval by blocking sodium and potassium ion channels, a mechanism shared with chloroquine. In acute overdose this produces QRS and QT widening and arrhythmias. In chronic use, the cardiac problems are rarer but better documented: cardiomyopathy and conduction abnormalities have been reported, mostly in older patients on high doses for long periods. Torsades de pointes is uncommon; a pooled estimate from COVID-19 studies put its incidence at about 3 per 1000 patients, and the cases that have been reported mostly involved overdose or severely ill patients. Because a corrected QT interval above 500 ms is associated with a substantially higher risk of torsades, baseline and periodic cardiovascular assessment, including an electrocardiogram and attention to electrolyte levels, is generally advised, particularly in patients with renal disease or other cardiac risk factors. In approved indications, QTc lengths in patients taking hydroxychloroquine alone or combined with other QT-prolonging drugs were reported to be similar, suggesting that the effect is modest when standard doses are used.\n\nOther reported effects\n\nGastrointestinal upset and nausea are common early complaints. Dermatological reactions include pruritus, rash and increased skin pigmentation, and neuromuscular effects include myopathy and muscle aches. Insomnia has also been reported. Clinical trial protocols have estimated that the dermatological, neuromuscular and sleep-related effects each occur in about 1% of patients and usually resolve within one to two weeks of continued treatment. Blood-count changes, including cytopenias and rare bone marrow suppression, are recognised, and hypoglycaemia is a labelled warning, particularly when the drug is combined with glucose-lowering agents such as insulin, because the drug can enhance the effect of blood glucose-lowering treatment.\n\nDrug interactions\n\nInteractions matter most where they add to cardiac or retinal risk. Co-prescription with other QT-prolonging drugs is the main cardiac concern; in a COVID-19 study, the combination with azithromycin was associated with a larger QTc increase than hydroxychloroquine alone, although the difference did not reach statistical significance. Tamoxifen increases retinal risk, and impaired renal clearance increases systemic exposure and therefore toxicity. Antacids can reduce oral absorption if taken at the same time. Prescribers are generally advised to review concomitant medications before starting treatment and when new drugs are added.\n\nEvidence base\n\nMost of the information on toxicity comes from observational cohort studies, case series, and national pharmacovigilance reports, rather than from randomised trials. Randomised trials are generally too short or too small to detect rare events such as retinal damage after many years of use or torsades de pointes. Spontaneous reports and post-marketing surveillance data were particularly important during the COVID-19 period, when hydroxychloroquine was given at high doses and frequently with other QT-prolonging drugs to severely ill patients, and this produced a wave of cardiac safety reports. Taken together, the data indicate that the drug is generally well tolerated when dosing is weight-based and monitoring is maintained, while the most serious risks are concentrated in long-term, high-dose, or high-risk use."
    },
    {
      "heading": "COVID-19 controversy and regulatory reversal",
      "text": "Hydroxychloroquine entered the COVID-19 debate in early 2020 for pharmacological reasons. Laboratory studies had found that chloroquine-class drugs could suppress SARS-CoV-2 in cell culture, and clinicians hoped that the drug's anti-inflammatory and immunomodulatory effects might blunt the harmful immune response seen in severe disease. Neither idea had been tested in patients at scale. The in vitro signal did not establish clinical benefit, and the randomized trials that followed were designed to test that gap directly.\n\nOn 28 March 2020, the US Food and Drug Administration (FDA) issued an emergency use authorization (EUA) for chloroquine and hydroxychloroquine. The Biomedical Advanced Research and Development Authority (BARDA) within the U.S. Department of Health and Human Services originally requested the EUA. The authorization covered use in hospitalized patients when a clinical trial was unavailable or participation was not feasible, and drugs from the Strategic National Stockpile were used under it. The agency also warned consumers a month later against taking the drugs to treat Covid-19 outside a hospital or formal clinical trial setting, citing the risk of serious heart rhythm problems.\n\nThe authorization was withdrawn on 15 June 2020. The FDA concluded that chloroquine and hydroxychloroquine were unlikely to be effective in treating COVID-19 for the authorized uses. It also judged that serious cardiac adverse events meant that the known and potential benefits no longer outweighed the risks. BARDA had asked for the revocation on the basis of new information, including clinical trial data.\n\nThe evidence that drove these decisions was mixed in its origins. A large observational study published in The Lancet on 22 May 2020 linked chloroquine or hydroxychloroquine use in hospitalized patients to higher mortality and heart rhythm complications. This paper was retracted after experts raised concerns about the veracity of the database used in the study. Even before the retraction, WHO experts had stated that mortality conclusions could not be definitively drawn from an observational study of this kind.\n\nThe WHO's SOLIDARITY trial was one of the most visible casualties of this episode. Its executive group implemented a temporary pause of the hydroxychloroquine arm while the safety data were reviewed, a decision taken on 25 May. The trial's data safety and monitoring committee then recommended that there were no reasons to modify the trial protocol, and the executive group endorsed the continuation of all arms of the Solidarity Trial, including hydroxychloroquine. The arm resumed in early June, but the episode showed how quickly a pause driven by uncertain observational data could affect a randomized programme.\n\nRandomized evidence then accumulated against benefit. On 4 June 2020, the independent Data Monitoring Committee of the UK RECOVERY trial reviewed unblinded data for the hydroxychloroquine arm at the request of the UK regulator. The chief investigators concluded that there was no beneficial effect of hydroxychloroquine in patients hospitalised with COVID-19 and stopped enrolling participants to that arm with immediate effect. In the preliminary report, 1542 patients were randomised to hydroxychloroquine and 3132 to usual care alone, and there was no significant difference in 28-day mortality (25.7% versus 23.5%). The full results were published in the New England Journal of Medicine in October 2020. Trials of post-exposure prophylaxis in uninfected contacts, including a US National Institutes of Health-supported study, likewise found no meaningful reduction in symptomatic infection, which removed the main rationale for use outside hospital.\n\nPublic promotion of the drug added a political dimension to the debate. President Trump was an early and vocal champion of the drugs, and even declared in May that he was taking the drugs to prevent COVID-19. Governments in several countries bought supplies in bulk during this period. The chief investigator of RECOVERY summarized the scientific objection in terms of evidence rather than policy: the drugs had been used very widely to treat COVID patients despite the absence of any good evidence.\n\nThe episode raised lasting questions about evidence standards in an emergency. Authorities acted on early laboratory data and small or observational studies, and the subsequent retraction and trial results showed the cost of that approach. Rapid, large randomized trials such as RECOVERY were presented as a way to reach firm conclusions faster, and the controversy continues to inform debates about how much weight urgent decisions should give to data that have not yet been peer reviewed."
    },
    {
      "heading": "Regulation, manufacturing and access",
      "text": "In the United States, hydroxychloroquine has been approved for medical use since 1955, and its current prescribing information covers four groups of indications. Malaria treatment and prophylaxis are approved in adult and pediatric patients, while rheumatoid arthritis, systemic lupus erythematosus and chronic discoid lupus erythematosus are approved for adults. The label also excludes complicated malaria from its approved use. Other regulators draw the boundaries differently. One clinical trial protocol summarises approvals by the FDA and the European Medicines Agency as covering malaria, rheumatoid arthritis (including juvenile idiopathic arthritis), and systemic and chronic discoid lupus erythematosus in adults and children. That is a wider paediatric scope than the US label, so the wording of each market's product information needs to be checked directly.\n\nHydroxychloroquine is a prescription-only medicine in the United States, the United Kingdom, Canada and Australia. The original brand, Plaquenil, was approved by the FDA in 1955, and the drug is now usually prescribed under its generic name and is produced by many manufacturers worldwide. Its scale of use is large: in 2023 it was the 131st most commonly prescribed medication in the United States, with more than 4 million prescriptions. Intellectual property history is also visible in the patent record. A US patent granted in 1951 covered the compound and its acid-addition salts for use against malaria, and a 1994 patent assigned to Sanofi covered compositions of the (S)-(+) enantiomer for malaria and lupus.\n\nThe sharpest access crisis came in March and April 2020. Public statements about the drug as a possible COVID-19 treatment drove up demand, and one St Louis rheumatologist found the entire local supply depleted within days. A survey of 334 US lupus patients conducted in spring 2020 found that 31% had difficulty getting refills, 5% could not refill their prescriptions, and 9% of those with problems ran out of the drug completely. Some health systems restricted refills; one provider changed its policy to allow refills in 14-day increments after first freezing prescriptions. Some states issued guidelines and emergency restrictions on dispensing to protect supply for lupus and rheumatoid arthritis patients. A later analysis of US claims data and Spanish hospital records, however, found that the increased use during March and April 2020 did not produce supply shortages for patients with rheumatoid arthritis and systemic lupus erythematosus in the United States. The risk to pregnant patients was a particular concern, since one physician argued that hydroxychloroquine is one of the few medicines able to reduce the risk of babies being born with lupus symptoms.\n\nThe World Health Organization includes hydroxychloroquine on its Essential Medicines List, where it appeared in the disease-modifying agents for rheumatic disorders section of the 2019 edition. The 24th list, published in 2025, also includes it. In the 2021 review cycle, an expert committee assessed a proposal to add the drug for cutaneous lupus, noting that hydroxychloroquine showed efficacy against placebo in cutaneous lupus and that its benefit-risk balance and probable affordability supported listing it. For low- and middle-income countries, price and reliable import channels matter more than the listing itself. Supply in parts of Africa, for example, has been linked to Asian manufacturers, and one Nigerian physician described them as likely to prefer to sell to the highest bidder during shortages.\n\nMuch of the drug's use falls outside its label. In the US, COVID-19 is not an approved indication; a drug monograph notes that its efficacy for the infection remains controversial and not FDA-approved, which is covered in the COVID-19 pandemic section. Paediatric use for sun-related skin conditions is another example, since the drug is approved for these conditions in adults, with unlicensed use in children. Prescribers in these situations rely on trial evidence, specialist society guidance and their own clinical judgement, and patients are normally expected to be informed of the unlicensed status of such treatment, in line with informed-consent principles."
    },
    {
      "heading": "Research frontiers and unresolved questions",
      "text": "Mechanisms and immune signalling\n\nEven after decades of clinical use, the cellular basis for many of the drug's effects is incompletely mapped. Studies continue to examine how the drug changes immune-cell signalling and why patients respond differently to the same dose. Most of the proposed explanations rest on laboratory and mechanistic work, and few have been confirmed in patients, so mechanistic findings are a weak basis for predicting clinical benefit in new indications. The retina is the clearest case of a mechanism with direct clinical consequences. Long-term HCQ therapy carries a risk of irreversible retinal toxicity caused by drug accumulation in the retinal pigment epithelium.\n\nPharmacogenomics and biomarkers\n\nPredicting who will develop toxicity is an unmet need. There is no consensus on specific biomarkers that may help identify the development of eye toxicity. Several candidates are under study:\n\n- Imaging. Structural OCT parameters, particularly alterations in the ellipsoid zone, outer nuclear layer, and retinal pigment epithelium, were consistently associated with early HCQ toxicity, often preceding functional impairment. A machine-learning study of 83 patients on the drug found that automated ellipsoid-zone measurements were higher in patients with retinopathy and correlated with the dose received, though the sample was small and the authors called for further validation.\n- Autoantibodies. Circulating anti-retinal autoantibodies have been detected in patients with retinopathy, and in one report they persist over time in the circulation and can associate with either a stable or progressive course of vision loss.\n- Genetics. Whole exome sequencing and genome-wide association studies have been used to identify candidate susceptibility genes in chloroquine and HCQ retinopathy. No genetic marker has yet been validated for routine screening.\n\nPrevalence estimates vary with the method used. Recent reports suggest that the prevalence of toxic retinopathy is about 4.3–13.8%, and figures are higher with modern imaging. Renal function is another variable of interest, since the drug is excreted from the kidneys, and patients with poor renal function need closer monitoring and lower doses. Cardiac toxicity, discussed elsewhere, likewise lacks a validated predictive biomarker.\n\nLong-term outcomes and dosing\n\nOpen questions include whether weight-based dosing can reduce retinal risk without loss of benefit in lupus and arthritis, how long the drug should be continued, and whether benefits extend to new indications. Answering these requires long follow-up, which is difficult for a drug used for decades by patients whose disease activity changes over time. Monitoring guidance has moved toward dose limits and earlier, structured screening, but the evidence base for those thresholds is largely observational.\n\nCOVID-19 trials and study design\n\nThe COVID-19 trials show how a drug can be tested rapidly yet still produce hard-to-interpret results. The RECOVERY trial randomised a total of 1542 patients to hydroxychloroquine and compared them with 3132 patients randomised to usual care alone. There was no significant difference in the primary endpoint of 28-day mortality (25.7% hydroxychloroquine vs. 23.5% usual care), and the chief investigators concluded that the data convincingly rule out any meaningful mortality benefit. The preliminary results were announced before peer review, a choice justified by the urgency of the pandemic. Despite its impressive speed, the trial only recruited about 10-15% of eligible patients, which limited the representativeness of the sample. A later analysis noted that the trial was not powered to detect such a ~10% increase in mortality, so pooling with other trials was used to estimate possible harm. A 2020 meta-analysis of thirteen randomised trials (n=18,540) found that hydroxychloroquine non-significantly increased mortality at 14 days (RR 1.07, 95%CI 0.92–1.25) or 30 days (RR 1.08, 95%CI 1.00–1.16). Subsequent pooled analyses have produced differing estimates, and a 2025 commentary reported that in a more recent meta-analysis, including more trials and with the final Solidarity results, the trend was weaker.\n\nCritics of the trial design argued that dosing began too late in disease for an antiviral to work. This debate illustrates the gap between preclinical antiviral activity and clinical efficacy: laboratory activity against the virus did not predict benefit in hospitalised patients, and the question of whether earlier treatment in outpatients would work was tested separately.\n\nEvidence quality and clinical guidance\n\nThe 2020 episode also shows how observational data can influence trial conduct. In May 2020, the decision to pause the WHO's SOLIDARITY trial, as well as others investigating chloroquine and hydroxychloroquine, was taken in response to the results of a large observational study published in The Lancet on 22 May 2020. That study concluded that the use of either chloroquine or hydroxychloroquine for hospitalised patients with COVID-19 was linked to an increased risk of serious heart rhythm complications and a decrease in in-hospital survival. The paper was later withdrawn after experts raised concerns about the veracity of the database used in the study. The WHO announced that it decided to resume studying hydroxychloroquine as a potential Covid-19 treatment in the trial shortly afterwards. The episode is often cited as a case in which the reliability of a single observational dataset, rather than randomised evidence, shaped the interpretation of a drug's safety for several days, and it underlines why guidance should rest on data whose provenance has been independently verified."
    }
  ],
  "links": [
    "chemistry",
    "medicine",
    "lymphocyte",
    "macrophage",
    "enantiomer",
    "malaria",
    "world-health-organization",
    "systemic-lupus-erythematosus",
    "rheumatoid-arthritis",
    "antibody",
    "molecule",
    "cardiovascular-disease",
    "covid-19",
    "randomized-controlled-trial",
    "autoimmune-disease",
    "ion-channel",
    "chronic-kidney-disease",
    "diabetes-mellitus",
    "glucose",
    "pandemic",
    "informed-consent"
  ],
  "sources": [
    {
      "title": "Hydroxychloroquine",
      "url": "https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540748/all/Hydroxychloroquine"
    },
    {
      "title": "Hydroxychloroquine: An old drug with new relevance",
      "url": "https://www.ccjm.org/content/85/6/459"
    },
    {
      "title": "Hydroxychloroquine",
      "url": "https://en.wikipedia.org/wiki/Hydroxychloroquine"
    },
    {
      "title": "FDA revokes emergency use for hydroxychloroquine, chloroquine",
      "url": "https://www.cidrap.umn.edu/news-perspective/2020/06/fda-revokes-emergency-use-hydroxychloroquine-chloroquine"
    },
    {
      "title": "Hydroxychloroquine Sulfate",
      "url": "https://www.chemspider.com/Chemical-Structure.12410.html"
    },
    {
      "title": "HYDROXYCHLOROQUINE SULFATE TABLETS, USP",
      "url": "https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=006801ed-d93f-4346-863a-cc03e6712520&type=display"
    },
    {
      "title": "PRODUCT INFORMATION August 2015 Plaquenil - hydroxychloroquine sulfate",
      "url": "https://www.tga.gov.au/sites/default/files/2024-07/FOI%205083%20Documents.pdf"
    },
    {
      "title": "Enantiomers of Chloroquine and Hydroxychloroquine Exhibit Different Activities Against SARS-CoV-2 *in vitro*, Evidencing *S*-Hydroxychloroquine as a Potentially Superior Drug for COVID-19",
      "url": "https://www.biorxiv.org/content/10.1101/2020.05.26.114033.full.pdf"
    },
    {
      "title": "Study of Anti-Malarials in Incomplete Lupus Erythematosus",
      "url": "https://cdn.clinicaltrials.gov/large-docs/18/NCT03030118/Prot_SAP_000.pdf"
    },
    {
      "title": "Hydroxychloroquine: Pharmacokinetics and Toxicity - Brouqui - 2024 - Journal of Clinical Pharmacy and Therapeutics - Wiley Online Library",
      "url": "https://onlinelibrary.wiley.com/doi/10.1155/2024/6500340"
    },
    {
      "title": "HYDROXYCHLOROQUINE SULFATE",
      "url": "https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=fe39f2c0-1b3d-486b-ad59-f88b28404d32&type=display"
    },
    {
      "title": "A dose-ranging study of the pharmacokinetics of hydroxy-chloroquine following intravenous administration to healthy volunteers - PubMed",
      "url": "https://pubmed.ncbi.nlm.nih.gov/3179169/"
    },
    {
      "title": "The Pharmacokinetic and Pharmacodynamic Properties of Hydroxychloroquine and Dose Selection for COVID-19: Putting the Cart Before the Horse - PMC",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC7395206/"
    },
    {
      "title": "Hydroxychloroquine (HCQ) in Pediatric Interstitial Lung Disease (ILD)",
      "url": "https://cdn.clinicaltrials.gov/large-docs/38/NCT02615938/Prot_000.pdf"
    },
    {
      "title": "A Study of Hydroxychloroquine vs Placebo to Prevent COVID-19 Infection in Patients Receiving Radiotherapy",
      "url": "https://cdn.clinicaltrials.gov/large-docs/88/NCT04381988/Prot_SAP_000.pdf"
    },
    {
      "title": "Hydroxychloroquine-related retinal toxicity",
      "url": "https://academic.oup.com/rheumatology/article/55/6/957/1744421"
    },
    {
      "title": "Hydroxychloroquine Toxicity - EyeWiki",
      "url": "https://eyewiki.org/Hydroxychloroquine_Toxicity"
    },
    {
      "title": "Full article: Hydroxychloroquine: a comprehensive review and its controversial role in coronavirus disease 2019",
      "url": "https://www.tandfonline.com/doi/full/10.1080/07853890.2020.1839959"
    },
    {
      "title": "Control of Heme Polymerase by Chloroquine and Other Quinoline Derivatives - ScienceDirect",
      "url": "https://www.sciencedirect.com/science/article/abs/pii/S0006291X83720607"
    },
    {
      "title": "Revealing Chloroquine’s Antimalarial Mechanism: The Suppression of Nucleation Events during Heme to Hemozoin Transformation",
      "url": "https://www.biorxiv.org/content/10.1101/2023.06.15.545078v1.full"
    },
    {
      "title": "Heme polymerase: Modulation by chloroquine treatment of a rodent malaria - ScienceDirect",
      "url": "https://www.sciencedirect.com/science/article/abs/pii/002432059290158L"
    },
    {
      "title": "all_antimalarial_drugs [TUSOM",
      "url": "https://tmedweb.tulane.edu/pharmwiki/doku.php/all_antimalarial_drugs"
    },
    {
      "title": "In Vitro Investigation Unveiling New Insights into the Antimalarial Mechanism of Chloroquine: Role in Perturbing Nucleation Events during Heme to β-Hematin Transformation - PubMed",
      "url": "https://pubmed.ncbi.nlm.nih.gov/37471056/"
    },
    {
      "title": "pmc.ncbi.nlm.nih.gov",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC7880079"
    },
    {
      "title": "Hydroxychloroquine inhibits proteolytic processing of endogenous TLR7 protein in human primary plasmacytoid dendritic cells",
      "url": "https://www.medrxiv.org/content/10.1101/2021.09.14.21263569.full.pdf"
    },
    {
      "title": "Hydroxychloroquine inhibits the mitochondrial antioxidant system in activated T cells: iScience",
      "url": "https://www.cell.com/iscience/fulltext/S2589-0042(21)01480-2"
    },
    {
      "title": "Advancements on the impact of hydroxychloroquine in systemic lupus erythematosus: Heliyon",
      "url": "https://www.cell.com/heliyon/fulltext/S2405-8440(24)06424-7"
    },
    {
      "title": "The effects of hydroxychloroquine and its promising use in refractory obstetric antiphospholipid syndrome",
      "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10796698/"
    },
    {
      "title": "Hydroxychloroquine directly reduces the bindin of antiphospholipid antibody-β2-glycoprotein I complexes to phospholipid bilayers",
      "url": "https://www.researchgate.net/publication/5277936_Hydroxychloroquine_directly_reduces_the_bindin_of_antiphospholipid_antibody-b2-glycoprotein_I_complexes_to_phospholipid_bilayers"
    },
    {
      "title": "(PDF) The effects of hydroxychloroquine and its promising use in refractory obstetric antiphospholipid syndrome",
      "url": "https://www.researchgate.net/publication/374143427_The_effects_of_hydroxychloroquine_and_its_promising_use_in_refractory_obstetric_antiphospholipid_syndrome"
    },
    {
      "title": "Hydroxychloroquine Reverses Thrombogenic Properties of Antiphospholipid Antibodies in Mice",
      "url": "https://www.ahajournals.org/doi/10.1161/01.CIR.96.12.4380"
    },
    {
      "title": "Hydroxychloroquine: A double‑edged sword (Review) - PMC",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC11868775/"
    },
    {
      "title": "Hydroxychloroquine in nephrology: current status and future directions - PubMed",
      "url": "https://pubmed.ncbi.nlm.nih.gov/37530940/"
    },
    {
      "title": "Hydroxychloroquine directly reduces the binding of antiphospholipid antibody–β2-glycoprotein I complexes to phospholipid bilayers",
      "url": "https://dx.doi.org/10.1182/blood-2008-03-144204"
    },
    {
      "title": "S-hydroxychloroquine prevents the antiphospholipid thrombogenic complexes for antiphospholipid syndrome treatment - ScienceDirect",
      "url": "https://www.sciencedirect.com/science/article/pii/S0753332225001623"
    },
    {
      "title": "Chloroquine - an overview",
      "url": "https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/chloroquine"
    },
    {
      "title": "Perspectives on repositioning chloroquine and hydroxychloroquine for the treatment of Covid-19 - PMC",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC7282440/"
    },
    {
      "title": "The History of Treating Lupus with Hydroxychloroquine - The Rheumatologist",
      "url": "https://www.the-rheumatologist.org/article/the-history-of-treating-lupus-with-hydroxychloroquine/"
    },
    {
      "title": "Hydroxychloroquine - American Chemical Society",
      "url": "https://www.acs.org/content/acs/en/molecule-of-the-week/archive/h/Hydroxychloroquine.html"
    },
    {
      "title": "DERMATOLOGIC CLINICS. 2. ANTIMALARIAL DRUGS IN THE THERAPY OF LUPUS ERYTHEMATOSUS - ScienceDirect",
      "url": "https://www.sciencedirect.com/science/article/pii/S0025619625100256"
    },
    {
      "title": "Coming Catastrophes with Chloroquine?",
      "url": "https://doi.org/10.7326/0003-4819-61-6-1203"
    },
    {
      "title": "Hydroxychloroquine, a less toxic derivative of chloroquine, is effective in inhibiting SARS-CoV-2 infection in vitro",
      "url": "https://www.nature.com/articles/s41421-020-0156-0"
    },
    {
      "title": "Revisiting hydroxychloroquine and chloroquine for patients with chronic immunity-mediated inflammatory rheumatic diseases",
      "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7282202/"
    },
    {
      "title": "Exploring insights of hydroxychloroquine, a controversial drug in Covid-19: An update - PMC",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC7959684/"
    },
    {
      "title": "Hydroxychloroquine (Plaquenil): Benefits, Side Effects and Dosing",
      "url": "https://www.lupus.org/resources/drug-spotlight-on-hydroxychloroquine"
    },
    {
      "title": "This label may not be the latest approved by FDA. For current ...",
      "url": "https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/009768s056lbl.pdf"
    },
    {
      "title": "Hydroxychloroquine",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC7339103/"
    },
    {
      "title": "Hydroxychloroquine and COVID-19: a Rheumatologist’s Take on the Lessons Learned",
      "url": "https://link.springer.com/article/10.1007/s11882-020-00983-9"
    },
    {
      "title": "Hydroxychloroquine Dosage Guide + Max Dose, Adjustments - Drugs.com",
      "url": "https://www.drugs.com/dosage/hydroxychloroquine.html"
    },
    {
      "title": "Hydroxychloroquine Uses, Dosage & Side Effects - Drugs.com",
      "url": "https://www.drugs.com/hydroxychloroquine.html"
    },
    {
      "title": "Plaquenil (hydroxychloroquine sulfate) dosing, indications, interactions, adverse effects, and more",
      "url": "https://reference.medscape.com/drug/plaquenil-hydroxychloroquine-sulfate-343205"
    },
    {
      "title": "WHO guidelines for malaria, 13 August 2025 - NCBI",
      "url": "https://www.ncbi.nlm.nih.gov/books/NBK588130/pdf/Bookshelf_NBK588130.pdf"
    },
    {
      "title": "Recommendations for the Prevention of Malaria Among Travelers",
      "url": "https://www.cdc.gov/mmwr/preview/mmwrhtml/00001584.htm"
    },
    {
      "title": "Current Trends Recommendations for the Prevention of Malaria in Travelers",
      "url": "https://www.cdc.gov/mmwr/preview/mmwrhtml/00000021.htm"
    },
    {
      "title": "Chapter 4: Prevention - Chemoprophylaxis regimens: Canadian recommendations for the prevention and treatment of malaria - Canada.ca",
      "url": "https://www.canada.ca/en/public-health/services/catmat/canadian-recommendations-prevention-treatment-malaria/chapter-4-prevention-chemoprophylaxis-regimen.html"
    },
    {
      "title": "Guidelines for Treatment of Malaria in the United States",
      "url": "https://ldh.la.gov/assets/oph/Center-PHCH/Center-CH/infectious-epi/EpiManual/MalariaManualTreatment.pdf"
    },
    {
      "title": "Physiologically-Based Pharmacokinetics Modeling for Hydroxychloroquine as a Treatment for Malaria and Optimized Dosing Regimens for Different Populations",
      "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9144775/"
    },
    {
      "title": "Hydroxychloroquine in lupus: emerging evidence supporting multiple beneficial effects - Tang - 2012 - Internal Medicine Journal - Wiley Online Library",
      "url": "https://onlinelibrary.wiley.com/doi/10.1111/j.1445-5994.2012.02886.x"
    },
    {
      "title": "Hydroxychloroquine use reduces mortality risk in systemic lupus erythematosus: A systematic review and meta-analysis of cohort studies - Tiantian Cai, Jing Zhao, Yanping Yang, Yanfei Jiang, Jin-an Zhang, 2022",
      "url": "https://dx.doi.org/10.1177/09612033221129774"
    },
    {
      "title": "Hydroxychloroquine in systemic lupus erythematosus: overview of current knowledge - Alina Dima, Ciprian Jurcut, François Chasset, Renaud Felten, Laurent Arnaud, 2022",
      "url": "https://journals.sagepub.com/doi/10.1177/1759720X211073001"
    },
    {
      "title": "Hydroxychloroquine Associated With Lower Glomerular Filtration Rate Decline in Lupus Nephritis",
      "url": "https://www.ovid.com/journals/arcar/fulltext/10.1002/acr.25616~hydroxychloroquine-associated-with-lower-glomerular"
    },
    {
      "title": "Hydroxychloroquine in Individuals At-risk for Type 1 Diabetes Mellitus",
      "url": "https://cdn.clinicaltrials.gov/large-docs/45/NCT03428945/Prot_000.pdf"
    },
    {
      "title": "Hydroxychloroquine sulfate tablets - accessdata.fda.gov",
      "url": "https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/214581s000lbl.pdf"
    },
    {
      "title": "Effects of hydroxychloroquine on symptomatic improvement in primary Sjögren syndrome: the JOQUER randomized clinical trial - PubMed",
      "url": "https://pubmed.ncbi.nlm.nih.gov/25027140/"
    },
    {
      "title": "Hydroxychloroquine treatment downregulates systemic interferon activation in primary Sjögren’s syndrome in the JOQUER randomized trial - PMC",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC6909893/"
    },
    {
      "title": "Efficacy and safety of iguratimod in patients with primary Sjögren’s syndrome: a multicentre randomised controlled trial",
      "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12718576/"
    },
    {
      "title": "Effect of hydroxychloroquine blood concentration on the efficacy and ocular toxicity of systemic lupus erythematosus",
      "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10984965/"
    },
    {
      "title": "Hydroxychloroquine for the Treatment of Hidradenitis Suppurativa",
      "url": "https://cdn.clinicaltrials.gov/large-docs/70/NCT03275870/ICF_002.pdf"
    },
    {
      "title": "The efficacy of hydroxychloroquine for obstetrical outcome in anti-phospholipid syndrome: Data from a European multicenter retrospective study - ScienceDirect",
      "url": "https://www.sciencedirect.com/science/article/abs/pii/S1568997215000270"
    },
    {
      "title": "The impact of hydroxychloroquine on obstetric outcomes in refractory obstetric antiphospholipid syndrome - ScienceDirect",
      "url": "https://www.sciencedirect.com/science/article/abs/pii/S0049384821004229"
    },
    {
      "title": "Hydroxychloroquine and pregnancy outcomes in patients with anti-phospholipid syndrome: a systematic review and meta-analysis - PMC",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC12410631/"
    },
    {
      "title": "Use of Hydroxychloroquine Is Associated With Improved Lipid Profile in Rheumatoid Arthritis Patients",
      "url": "https://www.ovid.com/jnls/jclinrheum/abstract/10.1097/rhu.0000000000000502~use-of-hydroxychloroquine-is-associated-with-improved-lipid?redirectionsource=fulltextview"
    },
    {
      "title": "Beneficial effects of hydroxychloroquine on blood lipids and glycated haemoglobin: A randomised interventional study in patients with rheumatoid arthritis and systemic lupus erythematosus",
      "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11515954/"
    },
    {
      "title": "Association between hydroxychloroquine use and risk of diabetes mellitus in systemic lupus erythematosus and rheumatoid arthritis: a UK Biobank-based study",
      "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11576225/"
    },
    {
      "title": "Hydroxychloroquine (oral route) - Side effects & dosage - Mayo Clinic",
      "url": "https://www.mayoclinic.org/drugs-supplements/hydroxychloroquine-oral-route/description/drg-20064216"
    },
    {
      "title": "Hydroxychloroquine in obstetric antiphospholipid syndrome: rationale and results of an observational study of refractory cases: The Journal of Maternal-Fetal & Neonatal Medicine: Vol 35, No 25",
      "url": "https://www.tandfonline.com/doi/abs/10.1080/14767058.2021.1908992"
    },
    {
      "title": "HYDROxychloroquine in Syndrome Primary AntiPhospholipid",
      "url": "https://clinicaltrials.gov/study/NCT04275778"
    },
    {
      "title": "Hydroxychloroquine: uses, dosing, warnings, adverse events, interactions",
      "url": "https://www.medcentral.com/drugs/monograph/5482-382319/hydroxychloroquine-oral"
    },
    {
      "title": "Hydroxychloroquine in children with proliferative lupus nephritis: a randomized clinical trial",
      "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10167107/"
    },
    {
      "title": "Relation between hydroxychloroquine dose and continuation rate in patients with systemic lupus erythematosus",
      "url": "https://academic.oup.com/mr/article/35/1/110/7737427"
    },
    {
      "title": "Lupus",
      "url": "https://www.healio.com/clinical-guidance/lupus/pharmacotherapeutic-option"
    },
    {
      "title": "Hydroxychloroquine Dosing Less Than 5 Mg/kg/day Leads to Increased Hospitalizations for Systemic Lupus Erythematosus Flares - ACR Meeting Abstracts",
      "url": "https://acrabstracts.org/abstract/hydroxychloroquine-dosing-less-than-5-mg-kg-day-leads-to-increased-hospitalizations-for-systemic-lupus-erythematosus-flares/"
    },
    {
      "title": "Hydroxychloroquine: 5 mg/kg/day Is Only the Starting Point",
      "url": "https://rheumnow.com/news/hydroxychloroquine-5-mgkgday-only-starting-point"
    },
    {
      "title": "Special AAO Report: Recommendations on Screening for Hydroxychloroquine Retinopathy (2025 Revision) - Ophthalmology",
      "url": "https://www.aaojournal.org/article/S0161-6420(25)00709-2/fulltext"
    },
    {
      "title": "Evaluating adherence to AAO hydroxychloroquine screening guidelines - ScienceDirect",
      "url": "https://www.sciencedirect.com/science/article/pii/S2950253524000716"
    },
    {
      "title": "ACR, AAD, RDS, and AAO 2020 Joint Statement on Hydroxychloroquine Use with Respect to Retinal Toxicity - 2021 - American Academy of Ophthalmology",
      "url": "https://www.aao.org/education/clinical-statement/acr-aad-rds-aao-2020-joint-statement-on-hydroxychl-2"
    },
    {
      "title": "Recommendations on Screening for Chloroquine and Hydroxychloroquine Retinopathy (2016 Revision) - Ophthalmology",
      "url": "https://www.aaojournal.org/article/S0161-6420(16)00201-3/fulltext"
    },
    {
      "title": "Dermatologists’ and Rheumatologists’ Adherence to the Latest Recommendations for Screening of Hydroxychloroquine Retinopathy in Saudi Arabia: A Cross-Sectional Study",
      "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11015938/"
    },
    {
      "title": "Recommendations on Screening for Hydroxychloroquine Retinopathy - 2026 - American Academy of Ophthalmology",
      "url": "https://www.aao.org/education/clinical-statement/revised-recommendations-on-screening-chloroquine-h"
    },
    {
      "title": "Cost-effectiveness of hydroxychloroquine retinopathy screening: the current guideline versus no screening and reduced regimens",
      "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11937206/"
    },
    {
      "title": "Trends and practices following the 2016 hydroxychloroquine screening guidelines",
      "url": "https://www.nature.com/articles/s41598-023-42816-5"
    },
    {
      "title": "Revised Recommendations on Screening for Chloroquine and Hydroxychloroquine Retinopathy - Ophthalmology",
      "url": "https://www.aaojournal.org/article/S0161-6420(10)01209-1/abstract"
    },
    {
      "title": "Hydroxychloroquine",
      "url": "https://mobile.fpnotebook.com/Rheum/Pharm/Hydrxychlrqn.htm"
    },
    {
      "title": "An open label study of the safety and efficacy of a single dose of weekly chloroquine and azithromycin administered for malaria prophylaxis in healthy adults challenged with 7G8 chloroquine-resistant Plasmodium falciparum in a controlled human malaria infection model",
      "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7493140/"
    },
    {
      "title": "Hydroxychloroquine for COVID-19 Post-exposure Prophylaxis (PEP)",
      "url": "https://cdn.clinicaltrials.gov/large-docs/61/NCT04328961/Prot_000.pdf"
    },
    {
      "title": "A Case Series and Review of Hydroxychloroquine Toxicity ...",
      "url": "https://www.cureus.com/articles/314587-a-case-series-and-review-of-hydroxychloroquine-toxicity-and-monitoring-how-do-we-dose-hydroxychloroquine.pdf"
    },
    {
      "title": "Hydroxychloroquine, QTc prolongation and risk of torsades de pointes - PMC",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC10711783/"
    },
    {
      "title": "Evaluating the Efficacy of Hydroxychloroquine and Azithromycin to Prevent Hospitalization or Death in Persons With COVID-19",
      "url": "https://cdn.clinicaltrials.gov/large-docs/68/NCT04358068/Prot_002.pdf"
    },
    {
      "title": "Chloroquine and Hydroxychloroquine Toxicity - StatPearls - NCBI Bookshelf",
      "url": "https://www.ncbi.nlm.nih.gov/books/NBK537086/"
    },
    {
      "title": "Retina screening rate in patients receiving hydroxychloroquine ‘remains low’",
      "url": "https://www.healio.com/news/rheumatology/20230711/retina-screening-rate-in-patients-receiving-hydroxychloroquine-remains-low"
    },
    {
      "title": "Healthcare Worker Exposure Response and Outcomes of Hydroxychloroquine",
      "url": "https://cdn.clinicaltrials.gov/large-docs/48/NCT04334148/Prot_000.pdf"
    },
    {
      "title": "Hydroxychloroquine Retinopathy in Systemic Lupus Erythematosus: Risk Factors, Screening, and Emerging Biomarkers - PMC",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC13358801/"
    },
    {
      "title": "FDA Revokes Emergency Use Authorization for Chloroquine and Hydroxychloroquine for COVID-19",
      "url": "https://www.dicardiology.com/article/fda-revokes-emergency-use-authorization-chloroquine-and-hydroxychloroquine-covid-19"
    },
    {
      "title": "Coronavirus update: FDA revokes emergency use of hydroxychloroquine",
      "url": "https://www.cnbc.com/2020/06/15/fda-revokes-emergency-use-of-hydroxychloroquine.html"
    },
    {
      "title": "FDA Revokes Emergency Use of Hydroxychloroquine",
      "url": "https://www.medscape.com/viewarticle/932368"
    },
    {
      "title": "The FDA Revokes Emergency Use Authorization for Hydroxychloroquine, Citing New Evidence",
      "url": "https://time.com/5853826/fda-hydroxychloroquine/"
    },
    {
      "title": "World Health Organization resumes hydroxychloroquine arm of COVID-19 SOLIDARITY trial - The Pharmaceutical Journal",
      "url": "https://pharmaceutical-journal.com/article/news/world-health-organization-resumes-hydroxychloroquine-arm-of-covid-19-solidarity-trial"
    },
    {
      "title": "WHO Pauses Hydroxychloroquine Arm Of COVID-19 Clinical Trial - After Lancet Study Finds Higher Mortality Rate Among Patients Getting The Drug - Health Policy Watch",
      "url": "https://healthpolicy-watch.org/world-health-organization-pauses-hydroxychloroquine-arm-of-multinational-covid-19-treatments-trial/"
    },
    {
      "title": "WHO Suspends Hydroxychloroquine Study Arm of COVID-19 Solidarity Trial",
      "url": "https://www.drugtopics.com/view/who-suspends-hydroxychloroquine-study-arm-covid-19-solidarity-trial"
    },
    {
      "title": "WHO resumes hydroxychloroquine coronavirus trials | Inquirer News",
      "url": "https://newsinfo.inquirer.net/1286119/who-resumes-hydroxychloroquine-coronavirus-trials"
    },
    {
      "title": "No clinical benefit from use of hydroxychloroquine in hospitalised patients with COVID-19 — RECOVERY Trial",
      "url": "https://www.recoverytrial.net/news/statement-from-the-chief-investigators-of-the-randomised-evaluation-of-covid-19-therapy-recovery-trial-on-hydroxychloroquine-5-june-2020-no-clinical-benefit-from-use-of-hydroxychloroquine-in-hospitalised-patients-with-covid-19"
    },
    {
      "title": "FDA Withdraws Emergency Use Authorization For Hydroxychloroquine",
      "url": "https://www.npr.org/sections/coronavirus-live-updates/2020/06/15/877498151/fda-withdraws-emergency-use-authorization-for-hydroxychloroquine"
    },
    {
      "title": "Hydroxychloroquine results — RECOVERY Trial",
      "url": "https://www.recoverytrial.net/results/hydroxychloroquine-results"
    },
    {
      "title": "Hydroxychloroquine has no benefit for hospitalised COVID-19 patients",
      "url": "https://www.europeanpharmaceuticalreview.com/news/120856/hydroxychloroquine-has-no-benefit-to-patients-hospitalised-with-covid-19-finds-trial/"
    },
    {
      "title": "Hydroxychloroquine: FDA revokes authorization of drug Trump touted",
      "url": "https://amp.cnn.com/cnn/2020/06/15/politics/fda-hydroxychloroquine-coronavirus/index.html"
    },
    {
      "title": "Label: HYDROXYCHLOROQUINE SULFATE tablet, film coated",
      "url": "https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=7804f5d2-41a6-4523-a277-6967e984e88e"
    },
    {
      "title": "Hydroxychloroquine Monitoring: A Common Drug Seen in Primary Care",
      "url": "https://practicingclinicians.com/the-exchange/hydroxychloroquine-monitoring-a-common-drug-seen-in-primary-care-"
    },
    {
      "title": "Lupus and arthritis patients facing hydroxychloroquine shortage",
      "url": "https://edition.cnn.com/2020/04/07/health/hydroxychloroquine-shortage-lupus-arthritis"
    },
    {
      "title": "Trump-touted hydroxychloroquine in short supply for lupus patients",
      "url": "https://medicalxpress.com/news/2020-06-trump-touted-hydroxychloroquine-short-lupus-patients.html"
    },
    {
      "title": "Stampede for Unproven Coronavirus Drug Harms Patients With Other Serious Diseases",
      "url": "https://www.nbcsandiego.com/news/investigations/stampede-for-unproven-coronavirus-drug-harms-patients-with-other-serious-diseases/2300619/"
    },
    {
      "title": "No Evidence of Hydroxychloroquine Shortages for Rheumatology Patients in the US During COVID-19 Pandemic - Rheumatology Advisor",
      "url": "https://www.rheumatologyadvisor.com/news/no-hcq-supply-shortage-rheumatology-patients-us-covid-19-pandemic/"
    },
    {
      "title": "Shortage of hydroxychloroquine hits mothers with lupus",
      "url": "https://medicalxpress.com/news/2020-04-shortage-hydroxychloroquine-mothers-lupus.html"
    },
    {
      "title": "hydroxychloroquine",
      "url": "https://www.guidetopharmacology.org/GRAC/LigandDisplayForward?ligandId=7198"
    },
    {
      "title": "2021 Expert Committee on Selection and Use of Essential Medicines",
      "url": "https://cdn.who.int/media/docs/default-source/essential-medicines/2021-eml-expert-committee/expert-reviews/i12_hydroxychloroquine_rev1.pdf?sfvrsn=444412ae_8"
    },
    {
      "title": "Hydroxychloroquine - Drug Monograph - MedQuizzify Blog",
      "url": "https://medquizzify.pharmacologymentor.com/blog/drug-monograph-hydroxychloroquine"
    },
    {
      "title": "Hydroxychloroquine for COVID-19: What is it and who makes it?",
      "url": "https://www.copperpodip.com/post/hydroxychloroquine-for-covid-19-what-it-is-and-who-makes-it"
    },
    {
      "title": "Optical Coherence Tomography and Angiography in Hydroxychloroquine Retinopathy: A Narrative Review",
      "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12896917/"
    },
    {
      "title": "Anti‐retinal Autoantibodies in Hydroxychloroquine Eye Toxicity - PMC",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC11694172/"
    },
    {
      "title": "Exome sequencing and genome-wide association analyses unveils the genetic predisposition in hydroxychloroquine retinopathy",
      "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11226719/"
    },
    {
      "title": "Decreased peri-parafoveal RPE, EZ and ELM intensity: A novel predictive biomarker for hydroxychloroquine retinal toxicity",
      "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11584423/"
    },
    {
      "title": "Effects of rapid recruitment and dissemination on Covid-19 mortality: the RECOVERY trial",
      "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7783530/"
    },
    {
      "title": "On meta-analytic models and the effect of hydroxychloroquine use in COVID-19",
      "url": "https://www.nature.com/articles/s41467-025-60478-x"
    },
    {
      "title": "Efficacy and Safety of Hydroxychloroquine for Hospitalized COVID-19 Patients: A Systematic Review and Meta-Analysis",
      "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8201261/"
    },
    {
      "title": "UK Covid-19 trial ends hydroxychloroquine study because there’s no evidence the drug benefits patients",
      "url": "https://www.cnn.com/2020/06/05/health/hydroxychloroquine-uk-recovery-trial-bn"
    },
    {
      "title": "Preliminary results from RECOVERY trial on the use of hydroxychloroquine in hospitalised patients with COVID-19",
      "url": "https://www.cambridgenetwork.co.uk/news/preliminary-results-recovery-trial-use-hydroxychloroquine-hospitalised-patients-covid-19"
    },
    {
      "title": "hcq-recovery-statement-050620-final-002.pdf",
      "url": "https://www.recoverytrial.net/files/hcq-recovery-statement-050620-final-002.pdf"
    },
    {
      "title": "The strange tale of hydroxychloroquine - by Robyn Chuter",
      "url": "https://robynchuter.substack.com/p/the-strange-tale-of-hydroxychloroquine"
    },
    {
      "title": "Automated Evaluation of Ellipsoid Zone At-Risk Burden for Detection of Hydroxychloroquine Retinopathy",
      "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11122588/"
    },
    {
      "title": "Hydroxychloroquine Retinopathy in a UK Single-Centre Cohort: A Retrospective Study of Risk Factors and Dosing Trends",
      "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12794433/"
    }
  ],
  "license": "https://creativecommons.org/licenses/by/4.0/"
}