Adult: In individuals travelling to malarious areas without chloroquine resistance: 400 mg once weekly, starting 2 weeks before travel to the endemic area; continue weekly doses while in the endemic area and for 4 weeks after leaving the area. Child: ≥31 kg: 6.5 mg/kg (up to 400 mg) once weekly, starting 2 weeks before travel to the endemic area; continue weekly doses while in the endemic area and for 4 weeks after leaving the area. Dosage recommendations may vary among countries or individual products. Refer to specific product guidelines.
Oral Rheumatoid arthritis
Adult: Initially, 400-600 mg daily as a single dose or in 2 divided doses. Maintenance: 200-400 mg daily as a single dose or in 2 divided doses, according to response. Use the minimum effective dose. Max: 6.5 mg/kg daily. Discontinue treatment if there is no improvement within 6 months. Child: ≥31 kg: Use the minimum effective dose. Max: 6.5 mg/kg daily. Treatment guidelines may vary among countries or individual products. Refer to specific product information.
Adult: 200 mg once daily or 400 mg daily as a single dose or in 2 divided doses. Alternatively, an initial dose of 400-800 mg daily for several weeks, then reduce to maintenance of 200-400 mg daily according to response. Use the minimum effective dose. Dosage recommendations may vary among countries or individual products. Refer to specific product guidelines. Child: ≥31 kg: Use the minimum effective dose. Max: 6.5 mg/kg daily. Treatment guidelines may vary among countries or individual products. Refer to specific product information.
Oral Uncomplicated malaria
Adult: For cases due to chloroquine-susceptible Plasmodium falciparum, Plasmodium malariae, Plasmodium vivax, and Plasmodium ovale: Initially, 800 mg, then 400 mg at 6, 24 and 48 hours after the initial dose. Total dose: 2,000 mg. Alternatively, 800 mg as a single dose. Child: ≥31 kg: Initially, 13 mg/kg (up to 800 mg), then 6.5 mg/kg (up to 400 mg) at 6, 24 and 48 hours after the initial dose. Total dose: 31 mg/kg (up to 2,000 mg). Dosage recommendations may vary among countries or individual products. Refer to specific product guidelines.
Oral Dermatological conditions caused or aggravated by sunlight
Adult: In patients able to receive 400 mg daily: Initially, 400 mg daily in divided doses; may be reduced to 200 mg if no further improvement is evident. Increase the maintenance dose to 400 mg daily if the response is reduced. Use the minimum effective dose. Max: 6.5 mg/kg daily. Treatment must only be given during periods of maximum light exposure. Treatment guidelines may vary among countries or individual products. Refer to specific product information.
Renal Impairment
Dosage reduction may be needed.
Hepatic Impairment
Dosage reduction may be needed.
Administration
Should be taken with food.
Contraindications
Pre-existing maculopathy of the eye.
Special Precautions
Patient with congenital or documented acquired QT prolongation and/or known risk factors for QT interval prolongation (e.g. heart failure, MI, bradycardia [<50 beats/min], history of ventricular dysrhythmias, uncorrected hypokalaemia and/or hypomagnesaemia, concomitant use with QT interval prolonging agents); G6PD deficiency, porphyria, psoriasis, sensitivity to quinine; severe gastrointestinal, neurological or blood disorders; myasthenia gravis. Renal and hepatic impairment. Children. Pregnancy and lactation.
Adverse Reactions
Significant: Prolonged QTc interval, retinopathy/irreversible retinal damage, myelosuppression (e.g. aplastic anaemia, agranulocytosis, leucopenia, thrombocytopenia), neuropsychiatric effects (e.g. psychosis, suicidal ideation and tendencies, hallucination, psychomotor agitation); skeletal muscle myopathy or neuropathy leading to progressive weakness and proximal muscle atrophy; worsening of psoriasis and porphyria, drug-induced phospholipidosis, proteinuria, extrapyramidal disorders (e.g. dystonia, dyskinesia, tremor). Ear and labyrinth disorders: Vertigo, tinnitus, sensorineural hearing loss. Eye disorders: Blurred vision, nystagmus, retinal pigmentation changes, visual field defects, macular degeneration, corneal opacities and oedema, decreased dark adaptation. Gastrointestinal disorders: Abdominal pain, diarrhoea, nausea, vomiting. General disorders and administration site conditions: Fatigue. Hepatobiliary disorders: Fulminant hepatic failure. Investigations: Abnormal LFTs, weight loss. Metabolism and nutrition disorders: Anorexia. Musculoskeletal and connective tissue disorders: Abnormal nerve conduction, depressed tendon reflexes. Nervous system disorders: Headache, dizziness, ataxia, seizure. Psychiatric disorders: Affect/emotional lability, irritability, nervousness, nightmares. Respiratory, thoracic and mediastinal disorders: Bronchospasm. Skin and subcutaneous tissue disorders: Rash, pruritus, urticaria, angioedema, alopecia, hair colour changes, photosensitivity, hyperpigmentation. Potentially Fatal: Cardiomyopathy resulting in cardiac failure, ventricular arrhythmias, severe hypoglycaemia; severe cutaneous adverse drug reactions (SCAR) including drug reaction with eosinophilia and systemic symptoms (DRESS), acute generalised exanthematous pustulosis (AGEP), Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN).
Patient Counseling Information
This drug may impair visual accommodation which can cause blurring of vision; if affected, do not drive or operate machinery.
Monitoring Parameters
Perform ophthalmological examination prior to initiation of treatment and repeated at least every 12 months. Obtain CBC with differential at baseline and periodically during long-term therapy. Correct electrolyte imbalances prior to use. Periodically assess muscle strength and deep tendon reflexes in patients on long-term therapy. Monitor cardiac function as clinically indicated; signs and symptoms of cardiomyopathy and serious skin reactions.
Overdosage
Symptoms: Headache, visual disturbance, convulsions, hypokalaemia, CV collapse, rhythm and conduction disorders (e.g. QT prolongation, torsades de pointes, ventricular tachycardia and ventricular fibrillation, width-increased QRS complex, bradyarrhythmias, nodal rhythm, atrioventricular block), followed by sudden respiratory and cardiac arrest. Life-threatening hypotension is common. CNS depression, transient blindness, and coma may also occur. Management: Symptomatic and supportive treatment. Immediately perform gastric lavage or induce emesis. Further absorption may be suppressed by administration of activated charcoal (in a dose ≥5 times that of the ingested amount) if introduced into the stomach by tube, following lavage, and within 30 minutes of ingestion. Parenteral diazepam may be beneficial in reversing cardiotoxicity. Institute respiratory support and shock management as necessary.
Drug Interactions
Increased risk of ventricular arrhythmias with other arrhythmogenic drugs or drugs that may potentially prolong QT interval such as class IA and III (e.g. amiodarone) antiarrhythmics, TCAs, antipsychotics, certain anti-infectives (e.g. moxifloxacin, azithromycin). May enhance the hypoglycaemic effects of antidiabetic drugs (e.g. insulin). Increased risk of seizures with other antimalarials known to lower the seizure threshold (e.g. mefloquine). May impair the activity of antiepileptic drugs. Increased incidence of adverse reactions with methotrexate. May increase the plasma levels of ciclosporin, metoprolol, and digoxin. May increase exposure with cimetidine. Reduced efficacy with rifampicin. May reduce the bioavailability of praziquantel and ampicillin. Absorption may be reduced by antacids and kaolin. Increased risk of retinal toxicity with tamoxifen. May inhibit the intracellular α-galactosidase activity when co-administered with agalsidase. May reduce the therapeutic effect of intradermal human diploid-cell rabies vaccine.
Action
Description: Hydroxychloroquine is a 4-aminoquinoline derivative. The exact mechanism by which it exhibits activity against Plasmodium is not known. However, hydroxychloroquine is a weak base, it may exert its effect by concentrating in the acid vesicles of the parasite and preventing the polymerisation of haeme. It can also inhibit certain enzymes through interaction with DNA. Furthermore, the precise mechanisms involved in its anti-inflammatory and immunomodulatory effects have not been fully elucidated. Pharmacokinetics: Absorption: Rapidly and almost completely absorbed. Bioavailability: 79%. Time to peak plasma concentration: Approx 3-4 hours. Distribution: Extensively distributed to body tissues. Crosses the placenta; enters breast milk (small amounts). Plasma protein binding: Approx 40%, mainly to albumin. Metabolism: Metabolised in the liver into desethylhydroxychloroquine (major metabolite), desethylchloroquine and bidesethylhydroxychloroquine. Excretion: Mainly via urine (approx 16-30% as unchanged drug). Elimination half-life: 30-60 days.
Chemical Structure
Hydroxychloroquine Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 3652, Hydroxychloroquine. https://pubchem.ncbi.nlm.nih.gov/compound/Hydroxychloroquine. Accessed Oct. 26, 2022.
P01BA02 - hydroxychloroquine ; Belongs to the class of aminoquinoline antimalarials.
References
Anon. Hydroxychloroquine Sulfate. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 07/07/2022.Anon. Hydroxychloroquine. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 07/07/2022.Buckingham R (ed). Hydroxychloroquine Sulfate. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 07/07/2022.Hydroxychloroquine Sulfate 200 mg Film-coated Tablets (Accord-UK Ltd). MHRA. https://products.mhra.gov.uk. Accessed 07/07/2022.Hydroxychloroquine Sulfate Film Coated Tablet (Jubilant Cadista Pharmaceuticals Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 07/07/2022.Joint Formulary Committee. Hydroxychloroquine Sulfate. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 07/07/2022.Plaquenil Tablet (Concordia Pharmaceuticals Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 07/07/2022.Plaquenil Tablet (Sanofi-Aventis [Malaysia] Sdn. Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 24/08/2022.Sanofi-Aventis New Zealand Limited. Plaquenil 200 mg Tablet, Film Coated data sheet 21 January 2022. Medsafe. http://www.medsafe.govt.nz. Accessed 07/07/2022.
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