Hydroxychloroquine: Indication, Dosage, Side Effect, Precaution

Generic Medicine Info Patient Medicine Information

This information is not country-specific. Please refer to the Malaysia prescribing information.

Generic Medicine Info

Indications and Dosage

Oral
Acute malaria

Adult: Initially, 800 mg, then 400 mg after 6-8 hr and a further 400 mg once daily for 2 succeeding days. Alternatively, 800 mg as single dose.
Child: Initially, 13 mg/kg as single dose then 6.5 mg/kg after 6, 24 and 48 hr.

Oral
Discoid and systemic lupus erythematosus, RA (rheumatoid arthritis)

Adult: Initially, 400 mg daily as single or in 2 divided doses. Maintenance: 200-400 mg daily, according to response. Max: 6.5 mg/kg/day or 400 mg daily, whichever is lower.
Child: Up to 6.5 mg/kg daily or 400 mg daily, whichever is lower.

Oral
Prophylaxis of malaria

Adult: Initially, 400 mg once wkly, 2 wk before exposure and continued until 8 wk after exposure. Alternatively, if 2-wk lead-in period is not possible, 800 mg as loading dose in 2 divided doses 6 hr apart, then 400 mg once wkly continued until 8 wk after exposure. All doses should be taken on same day of each wk.
Child: 6.5 mg/kg once wkly, 2 wk before exposure and continued until 8 wk after exposure. Alternatively, if 2-wk lead-in period is not possible, 13 mg/kg as loading dose in 2 divided doses 6 hr apart, then once wkly treatment for 8 wk after exposure. All doses should be taken on same day of each wk.

Administration

Should be taken with food.

Contraindications

Pre-existing maculopathy of the eye.

Special Precautions

Patient w/ G6PD deficiency, DM, haematological and GI disorders, alcoholism, porphyria, psoriasis. Renal and hepatic impairment. Childn. Pregnancy and lactation.

Adverse Reactions

Significant: Cardiomyopathy (e.g. AV block, pulmonary HTN, sick sinus syndrome), myocardial toxicity, QT interval prolongation, ventricular arrhythmia, torsade de pointes; skin reactions; bone marrow suppression (e.g. agranulocytosis, anaemia, aplastic anaemia, leucopenia, thrombocytopenia); proximal myopathy or neuromyopathy leading to progressive weakness, proximal muscle atrophy, depressed tendon reflexes, abnormal nerve conduction. Rarely, suicidal behaviour; keratopathy, retinopathy.
Nervous: Ataxia, dizziness, emotional disturbance, emotional lability, headache, irritability, lassitude, nerve deafness, nervousness, nightmares, psychosis, seizures, vertigo.
GI: Anorexia, diarrhoea, nausea, stomach cramps, vomiting.
Resp: Bronchospasm.
Hepatic: Acute hepatic failure. Rarely, hepatic insufficiency.
Endocrine: Exacerbation of porphyria, wt loss.
Haematologic: Haemolysis in G6PD deficiency.
Ophthalmologic: Accommodation disturbance, corneal changes (e.g. transient oedema, punctuate to linear opacities, decreased sensitivity, deposits, visual disturbances, blurred vision, photophobia), decreased visual acuity, macular oedema, nystagmus, optic disk disorder, retinal pigment changes, retinal vascular disease, retinitis pigmentosa, scotoma, vision color changes, visual field defect.
Otic: Tinnitus.
Dermatologic: Acute generalised exanthematous pustulosis, alopecia, bleaching of hair, bullous rash, dyschromia, annulare centrifugum erythema, erythema multiforme, exacerbation of psoriasis, exfoliative dermatitis, lichenoid eruption, maculopapular rash, morbilliform rash, pruritus, skin photosensitivity, Stevens-Johnson syndrome, toxic epidermal necrolysis, urticaria, purpuric rash.
Immunologic: Hypersensitivity reactions (e.g. angioedema).
Potentially Fatal: Cardiac failure, severe hypoglycaemia.

Patient Counseling Information

This drug may cause dizziness and blurred vision, if affected, do not drive or operate machinery.

Monitoring Parameters

Monitor for signs/symptoms of cardiac compromise; CBC, serum glucose, proximal muscle strength and reflexes, LFT, renal function. Perform baseline and periodic eye examination.

Overdosage

Symptoms: Headache, visual disturbances, CV collapse, convulsions, and hypokalaemia. Rhythm and conduction disorders, including QT prolongation, Torsades de Pointes, ventricular tachycardia and ventricular fibrillation, followed by sudden potentially fatal resp and cardiac arrest. Management: Symptomatic and supportive treatment. Perform gastric lavage or emesis immediately. Activated charcoal can be introduced into the stomach by tube following lavage w/in 30 min of ingestion, given in a dose at least 5 times of the overdose to inhibit further absorption. Administer diazepam IV to reverse cardiotoxicity. Resp support and shock management should be instituted as needed.

Drug Interactions

Hydroxychloroquine may enhance the effect of hypoglycaemic agents. May increase plasma digoxin level. Increased risk of Torsades de pointes w/ QTc-prolonging agents (e.g. disopyramide, quinidine, amiodarone, sotalol, cisapride). Increased risk of convulsion w/ mefloquine. Antacids may interfere w/ hydroxychloroquine absorption.

Action

Description: Hydroxychloroquine is a 4-aminoquinoline derivative. It interferes w/ parasite digestive vacuoles by increasing pH and interfering w/ parasite’s ability to metabolise and utilise erythrocyte Hb. The mechanism of action in the treatment of rheumatoid arthritis and lupus erythematosus has not been fully elucidated.
Pharmacokinetics:
Absorption: Rapidly and completely absorbed. Time to peak plasma concentration: 1.83 hr.
Distribution: Widely distributed in the body. Crosses the placenta and enters breast milk (small amounts). Plasma protein binding: Approx 40%, mainly to albumin.
Metabolism: Metabolised in the liver into desethylhydroxychloroquine and desethylchloroquine (major metabolites) and small amount of bisdesethylchloroquine.
Excretion: Via urine (15-25% as metabolites, ≤60% as unchanged drug). Elimination half-life: Approx 40 days.

Chemical Structure

Storage

Store between 20-25°C. Protect form light.

MIMS Class

Antimalarials / Disease-Modifying Anti-Rheumatic Drugs (DMARDs)

ATC Classification

P01BA02 - hydroxychloroquine ; Belongs to the class of aminoquinoline antimalarials.

References

Anon. Hydroxychloroquine. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 28/06/2017.

Buckingham R (ed). Hydroxychloroquine Sulfate. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 28/06/2017.

Joint Formulary Committee. Hydroxychloroquine Sulfate. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 28/06/2017.

McEvoy GK, Snow EK, Miller J et al (eds). Hydroxychloroquine Sulfate. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 28/06/2017.

Plaquenil 200mg Film-Coated Tablets (Winthrop Pharmaceuticals UK Limited). MHRA. https://products.mhra.gov.uk/. Accessed 28/06/2017.

Plaquenil Tablet (Concordia Pharmaceuticals Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 28/06/2017.

Plaquenil Tablet Film Coated (Sanofi-Aventis US LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 28/06/2017.

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