chloroquine (Rx)

Frequency Not Defined

Abnormal ECG

Prolonged QT interval

Amnesia

Pruritus

Diarrhea,

Loss of appetite

Nausea

Stomach cramps

Vomiting

Methemoglobinemia (rare)

Muscle weakness

Retinopathy

Contraindications

Hypersensitivity to chloroquine, 4-aminoquinolones

Psoriasis, porphyria, retinal or visual field changes

Cautions

For prevention, may use proguanil concomitantly

Shown to cause severe hypoglycemia including loss of consciousness that could be life-threatening in patients treated with or without antidiabetic medications; patients should be warned about risk of hypoglycemia and associated clinical signs and symptoms; patients presenting with clinical symptoms suggestive of hypoglycemia during treatment with chloroquine should have blood glucose level checked and treatment reviewed as necessary

Not effective in most areas; CDC recommends mefloquine or atovaquone/proguanil - check CDC traveler information for specific recommendations for region

May cause hemolysis in glucose-6 phosphate dehydrogenase (G-6-PD) deficiency; blood monitoring may be needed as hemolytic anemia may occur, in particular in association with other drugs that cause hemolysis

Monitor CBC periodically with prolonged therapy

Caution with history of auditory damage

Caution with hepatic disease, alcoholism, and coadministration with other hepatotoxic drugs

May provoke seizures in patients with history of epilepsy

Antacids and kaolin reduce chloroquine absorption; separate administration by at least 4 hr

Irreversible retinal damage observed in some patients; significant risk factors for retinal damage include daily doses of chloroquine phosphate > 2.3 mg/kg of actual body weight, durations of use greater than five years, subnormal glomerular filtration, use of some concomitant drug products such as tamoxifen citrate, and concurrent macular disease

A baseline ophthalmological examination should be performed within the first year of initiating therapy; for individuals with significant risk factors, monitoring should include annual examinations; discontinue if ocular toxicity is suspected; patient should be closely observed given that retinal changes (and visual disturbances) may progress even after cessation of therapy

In individuals of Asian descent, retinal toxicity may first be noticed outside macula; it is recommended that visual field testing be performed in visual field of central 24 degrees instead of central 10 degrees

May exacerbate heart failure

Not effective against chloroquine- or hydroxychloroquine-resistant strains of Plasmodium species; information regarding geographic areas where resistance to chloroquine occurs, is available at the Centers for Disease Control and Prevention (www.cdc.gov\malaria)

Does not treat hypnozoite liver stage forms of Plasmodium and will therefore not prevent relapses of malaria due to P. vivax or P. ovale; additional treatment with an anti-malarial agent active against these forms, such as an 8-aminoquinoline, is required for the treatment of infections with P. vivax and P. ovale

Cases of cardiomyopathy resulting in cardiac failure, in some cases with fatal outcome, reported during long term therapy at high doses; monitor for signs and symptoms of cardiomyopathy and discontinue chloroquine if cardiomyopathy develops; chronic toxicity should be considered when conduction disorders (bundle branch block / atrio-ventricular heart block) diagnosed; if cardiotoxicity suspected, prompt therapy discontinuation may prevent life-threatening complications

QT interval prolongation, torsades de pointes, and ventricular arrhythmias reported; risk is greater if chloroquine is administered at high doses; fatal cases reported; use with caution in patients with cardiac disease, a history of ventricular arrhythmias, uncorrected hypokalemia and/or hypomagnesemia, or bradycardia (?50 bpm), and during concomitant administration with QT interval prolonging agents due to potential for QT interval prolongation

Pregnancy

There are no adequate and well-controlled studies evaluating the safety and efficacy of chloroquine in pregnant women; usage during pregnancy should be avoided except in prophylaxis or treatment of malaria when benefit outweighs potential risk to fetus

Lactation

Because of the potential for serious adverse reactions in nursing infants from chloroquine, a decision should be made whether to discontinue nursing or to discontinue drug, taking into account potential clinical benefit of drug to mother

Mechanism of Action

Active against erythrocytic forms of Plasmodium vivax & P. malariae and most strains of Plasmodium falciparum

Precise mechanism not known

Absorption

Bioavailability: ~89%

Peak plasma time: 1-2 hr

Distribution

Distributed widely in body tissues (eg, eyes, heart, kidneys, liver, lungs) where retention prolonged; crosses placenta; enters breast milk

Metabolism

Partially in liver

Elimination

Half-life: 3-5 days

Excretion: urine (~70% as unchanged drug); acidification of urine increases elimination

Small amounts may be present in urine months following discontinuation of therapy