Adult: Doses are expressed in terms of chloroquine phosphate (each 250 mg chloroquine phosphate is equivalent to approx 150 mg chloroquine base). For the treatment of cases due to chloroquine-sensitive Plasmodium falciparum and Plasmodium malariae: Initially, 1,000 mg (600 mg base) as a single dose, followed by 500 mg (300 mg base) 6-8 hours after the initial dose, and then 500 mg (300 mg base) daily for 2 days. For the treatment of cases due to chloroquine-sensitive Plasmodium vivax and Plasmodium ovale: In combination with primaquine or tafenoquine: Initially, 1,000 mg (600 mg base) as a single dose, followed by 500 mg (300 mg base) 6-8 hours after the initial dose, and then 500 mg (300 mg base) daily for 2 days. Total dose: 2,500 mg (1,500 mg base) given over 3 days. Child: Doses are expressed in terms of chloroquine phosphate (each 16.7 mg chloroquine phosphate is equivalent to approx 10 mg chloroquine base). For the treatment of cases due to chloroquine-sensitive Plasmodium falciparum and Plasmodium malariae: Initially, 16.7 mg/kg (10 mg/kg base) as a single dose, followed by 8.3 mg/kg (5 mg/kg base) 6-8 hours after the initial dose, and then 8.3 mg/kg (5 mg/kg base) daily for 2 days. For the treatment of cases due to chloroquine-sensitive Plasmodium vivax and Plasmodium ovale: In combination with primaquine or tafenoquine: Initially, 16.7 mg/kg (10 mg/kg base) as a single dose, followed by 8.3 mg/kg (5 mg/kg base) 6-8 hours after the initial dose, and then 8.3 mg/kg (5 mg/kg base) daily for 2 days. Max: 1,000 mg (600 mg base) for the initial dose; 500 mg (300 mg base) for subsequent doses. Child doses must not exceed adult doses regardless of weight. Total dose: 41.6 mg/kg (25 mg/kg base) given over 3 days.
Oral Rheumatoid arthritis
Adult: Doses are expressed in terms of chloroquine phosphate (each 250 mg chloroquine phosphate is equivalent to approx 150 mg chloroquine base). Usual dose: 250 mg (150 mg base) daily. Discontinue treatment if there is no improvement after 6 months.
Adult: Doses are expressed in terms of chloroquine phosphate (each 250 mg chloroquine phosphate is equivalent to approx 150 mg chloroquine base). Initially, 250 mg (150 mg base) once daily or bid for 1 or 2 weeks, followed by a maintenance dose of 250 mg (150 mg base) daily. Dosage recommendations may vary among individual products or between countries (refer to detailed product guidelines).
Oral Hepatic amoebiasis
Adult: Doses are expressed in terms of chloroquine phosphate (each 250 mg chloroquine phosphate is equivalent to approx 150 mg chloroquine base). Usual dose: 1,000 mg (600 mg base) daily for 2 days, followed by 250 mg (150 mg base) bid for 2-3 weeks. Therapy is usually combined with intestinal amoebicide.
Oral Prophylaxis of malaria
Adult: Doses are expressed in terms of chloroquine phosphate (each 250 mg chloroquine phosphate is equivalent to approx 150 mg chloroquine base). In geographic areas where chloroquine resistance is not present: 500 mg (300 mg base) once weekly, given on the same day each week. Start 1-2 weeks before exposure; continue weekly doses during the stay and for at least 4 weeks after leaving the endemic area. Child: Doses are expressed in terms of chloroquine phosphate (each 16.7 mg chloroquine phosphate is equivalent to approx 10 mg chloroquine base). In geographic areas where chloroquine resistance is not present: 8.3 mg/kg (5 mg/kg base) once weekly, given on the same day each week. Max: 500 mg (300 mg base) once weekly regardless of weight. Start 1-2 weeks before exposure; continue weekly doses during the stay and for at least 4 weeks after leaving the endemic area.
Administration
Should be taken with food.
Contraindications
Presence of retinal or visual field changes of any cause (when used for indications other than acute malaria). Concomitant use with amiodarone.
Special Precautions
Patient with congenital or documented acquired QT prolongation and known risk factors for QT interval prolongation (e.g. cardiac disease, history of ventricular arrhythmias, bradycardia [<50 bpm], uncorrected hypokalaemia and/or hypomagnesaemia, concomitant use with agents that prolong QT interval); pre-existing auditory damage, myasthenia gravis, porphyria, psoriasis, G6PD deficiency, alcoholism; neurological disorders (particularly history of epilepsy), severe gastrointestinal disease. When indicated for prophylaxis of malaria, consider official country guidelines and local information on the prevalence of resistance to anti-malarial agents. Hepatic and renal impairment. Children. Pregnancy and lactation.
Adverse Reactions
Significant: Retinal toxicity which may cause irreversible retinopathy (high doses and prolonged use); hearing defects, proteinuria (with or without moderate decrease in GFR); skeletal muscle myopathy or neuropathy, resulting in progressive weakness and atrophy of proximal muscle groups; abnormal nerve conduction, acute extrapyramidal disorders, new onset or worsening of myasthenia gravis; exacerbation of porphyria and psoriasis, drug reaction with eosinophilia and systemic symptoms (DRESS); suicidal behaviour, psychiatric disorders; increased risk of haemolytic anaemia (particularly in patients with G6PD deficiency). Rarely, haematologic reactions (e.g. reversible agranulocytosis, neutropenia, aplastic anaemia, pancytopenia, thrombocytopenia); convulsions, diffuse parenchymal lung disease. Ear and labyrinth disorders: Tinnitus, nerve type deafness, hypoacusis. Eye disorders: Blurred vision, diplopia, visual field defects, accommodation disorder, macular degeneration, maculopathy, reversible corneal opacity, pigmented deposits, macular defects of colour vision, optic atrophy, scotomas. Gastrointestinal disorders: Nausea, vomiting, diarrhoea, abdominal pain or cramps. Hepatobiliary disorders: Hepatitis. Immune system disorders: Hypersensitivity and anaphylactic reactions, including angioedema. Investigations: Increased liver enzymes, ECG changes. Metabolism and nutrition disorders: Anorexia. Nervous system disorders: Headache, polyneuropathy. Psychiatric disorders: Insomnia, confusion, anxiety, personality changes, hallucination, depression. Skin and subcutaneous tissue disorders: Pruritus, skin photosensitivity, urticaria, alopecia, bleaching of hair pigment, Stevens-Johnson syndrome, toxic epidermal necrolysis, erythema multiforme; bluish-black pigmentation of the skin, mucous membrane and nails. Vascular disorders: Hypotension. Potentially Fatal: Cardiomyopathy leading to cardiac failure (prolonged use at high doses), QT prolongation, torsades de pointes, ventricular arrhythmias; severe hypoglycaemia, including loss of consciousness.
Patient Counseling Information
This drug may affect visual accommodation which may lead to blurred and/or double vision; if affected, do not drive or operate machinery.
Monitoring Parameters
Monitor CBC with differential, LFTs, and renal function at baseline and regularly during treatment; blood glucose, muscle strength (particularly proximal muscles) during long-term use; ECG at baseline and as clinically necessary (particularly in patients with an increased risk of QT prolongation). Perform ophthalmologic exam (fundus exam within the 1st year plus visual fields and spectral-domain optical coherence tomography if with maculopathy) at baseline then screen annually starting after 5 years of use (or sooner if major risk factors are present). Assess for signs and symptoms of cardiomyopathy, retinopathy, hearing defects, and psychiatric reactions.
Overdosage
Symptoms: Nausea, vomiting, hypokalaemia, metabolic acidosis, headache, dizziness, blurred vision, diplopia, hypotension (may progress to cardiogenic shock and pulmonary oedema), width-increased QRS complex, bradyarrhythmias, nodal rhythm, QT prolongation, AV block, ventricular tachycardia, torsades de pointes, ventricular fibrillation, and cardiac arrest. Circulatory collapse due to potent cardiotoxic effects, respiratory arrest, and coma may also occur. Rarely, hepatotoxicity, gastric haemorrhage, nephritis, haematological abnormalities, psychiatric features, blindness, restlessness, excitability, and convulsions may be present. Management: Symptomatic and supportive treatment. Maintain a clear airway and ensure adequate ventilation. Immediately perform gastric lavage or induce emesis. May consider the administration of activated charcoal within 1 hour of ingestion. To correct metabolic acidosis, consider giving IV Na bicarbonate. Administration of epinephrine and diazepam infusions may reduce the cardiotoxic effects of chloroquine.
Drug Interactions
May increase the serum levels of ciclosporin and digoxin. Increased risk of convulsions with mefloquine. May inhibit the actions of antiepileptic drugs. Absorption may be reduced with antacids (e.g. Al, Ca, and Mg salts) and adsorbents (e.g. kaolin). May suppress the antibody response to pre-exposure primary immunisation with intradermal human diploid-cell rabies vaccine. May reduce the serum levels of praziquantel. May diminish the therapeutic effects of neostigmine and pyridostigmine. Cimetidine may inhibit the metabolism of chloroquine leading to increased plasma concentration. May enhance the hypoglycaemic effects of insulin and other antidiabetic drugs. Increased risk of retinal toxicity with tamoxifen. May inhibit the intracellular α-galactosidase activity of agalsidase alfa and agalsidase beta. Potentially Fatal: Increased risk of ventricular arrhythmia with agents known to prolong QT interval such as halofantrine, class IA and III (e.g. amiodarone) antiarrhythmics, TCAs, antipsychotics and certain anti-infectives (e.g. moxifloxacin). Increased risk of CV events and CV mortality with macrolide antibiotics (e.g. azithromycin, clarithromycin, erythromycin).
Food Interaction
Bioavailability may be increased with food.
Action
Description: Mechanism of Action: Chloroquine is a 4-aminoquinoline anti-protozoal agent. The exact mechanism by which it exerts its antimalarial effect is unknown; however, it may exert its effect against Plasmodium species by concentrating in the parasite’s acid vesicles and by inhibiting the polymerisation of haeme. Additionally, it binds to and inhibits DNA and RNA polymerase. Its precise mechanisms of action on rheumatoid arthritis and lupus erythematosus are not completely elucidated, but it is reported to antagonise histamine in vitro and prevents prostaglandin effects in mammalian cells possibly by inhibiting arachidonic acid conversion to prostaglandin F2. It may also have antiserotonin effects. Pharmacokinetics: Absorption: Rapidly and almost completely absorbed from the gastrointestinal tract. Increased bioavailability with food. Time to peak plasma concentration: 1-2 hours. Distribution: Widely distributed in the body tissues including eyes, skin, heart, kidneys, liver, lungs, spleen and leucocytes. Crosses the placenta; enters breast milk (small amounts). Plasma protein binding: Approx 50-70%. Metabolism: Partially metabolised in the liver to the main metabolite, desethylchloroquine. Bisdesethylchloroquine and other metabolites are also formed in small amounts. Excretion: Via urine (approx 70%; approx 35% as unchanged drug). Elimination half-life: 74.7 ± 30.1 hours.
Chemical Structure
Chloroquine Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 2719, Chloroquine. https://pubchem.ncbi.nlm.nih.gov/compound/Chloroquine. Accessed Mar. 28, 2023.
Storage
Store between 15-30°C. Protect from light and moisture.
P01BA01 - chloroquine ; Belongs to the class of aminoquinoline antimalarials.
References
Anon. Chloroquine. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 22/03/2023.Anon. Chloroquine. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 11/01/2023.Avoclor 250 mg Tablets (Alliance Pharmaceuticals Limited). MHRA. https://products.mhra.gov.uk. Accessed 11/01/2023.Axcel Chloroquine Tablet (Kotra Pharma [M] Sdn. Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 11/01/2023.Buckingham R (ed). Chloroquine. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 11/01/2023.Chloroquine Phosphate Tablet (Amneal Pharmaceuticals of New York LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 11/01/2023.Joint Formulary Committee. Chloroquine. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 11/01/2023.Malaviron Syrup (Wallace Manufacturing Chemists Ltd.). MHRA. https://products.mhra.gov.uk. Accessed 11/01/2023.
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