Home Drug Guide Chloroquine Phosphate

Drug Guide

Generic Name

Chloroquine Phosphate

Brand Names Aralen

Classification

Therapeutic: Antimalarial agent

Pharmacological: Aminoquinoline antimalarial agent

FDA Approved Indications

Prophylaxis of malaria caused by Plasmodium vivax, P. ovale, P. malariae, and sensitive strains of P. falciparum; Treatment of uncomplicated chloroquine-sensitive malaria.

Mechanism of Action

Chloroquine accumulates in the parasite's food vacuole, interfering with hemoglobin digestion and leading to toxic accumulation of free heme, which damages the parasite.

Dosage and Administration

Adult: Prophylaxis: 250 mg once weekly starting 1-2 weeks before exposure, during, and 4 weeks after exposure; Treatment: 620 mg at 0 hours, 620 mg after 6-8 hours, then 620 mg once daily for 2 days.

Pediatric: Dosing based on weight, typically 5 mg/kg/day for prophylaxis, and 10 mg/kg at treatment doses.

Geriatric: Use with caution; consider comorbidities and drug interactions.

Renal Impairment: Adjust dose as needed; contraindicated in severe impairment.

Hepatic Impairment: Use cautiously; no specific adjustment available.

Pharmacokinetics

Absorption: Well absorbed orally, with bioavailability of approximately 76%.

Distribution: Wide tissue distribution, including eyes, liver, skin, and spleen.

Metabolism: Primarily metabolized in the liver.

Excretion: Excreted mainly via kidneys; small amount in feces.

Half Life: Approximately 1-2 months due to extensive tissue binding.

Contraindications

History of retinopathy of any etiology.
Hypersensitivity to chloroquine or 4-aminoquinoline compounds.

Precautions

Pre-existing visual disturbances.
Neurologic disorders.
Blood dyscrasias.
Use with caution in patients with hepatic or renal impairment.

Adverse Reactions - Common

Gastrointestinal disturbances (nausea, vomiting, diarrhea) (Common)
Headache, dizziness (Common)
Skin rash, pruritus (Common)

Adverse Reactions - Serious

Retinopathy and visual impairment (potentially permanent) (Serious, dose- and duration-dependent)
Cardiomyopathy, QT prolongation leading to arrhythmias (Serious)
Blood dyscrasias (e.g., leukopenia, thrombocytopenia) (Serious)

Drug-Drug Interactions

Methotrexate (increased toxicity)
Digoxin (potential toxicity)
Quinidine and other QT-prolonging agents

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Baseline ocular and cardiac assessments including ECG; monitor for visual changes and cardiac arrhythmias.

Diagnoses:

Risk of visual impairment related to retinopathy.
Risk of cardiac arrhythmias.

Implementation: Administer with food to minimize gastrointestinal upset; monitor ECG periodically during therapy; instruct patient to report vision changes immediately.

Evaluation: Regular eye examinations; periodic ECG monitoring; assessment of symptom resolution in malaria treatment.

Patient/Family Teaching

Take medication exactly as prescribed.
Complete the full course of therapy.
Report any visual changes, severe dizziness, or heartbeat irregularities immediately.
Use caution when operating machinery or driving.
Avoid excessive alcohol and concomitant use of other QT-prolonging medications.

Special Considerations

Black Box Warnings:

Potential for irreversible visual damage with long-term use.

Genetic Factors: G6PD deficiency may increase risk of hemolysis with some related drugs, but not specifically with chloroquine.

Lab Test Interference: May cause false-positive urine tests for protein, glucose, or ketones.

Overdose Management

Signs/Symptoms: Nausea, vomiting, diarrhea, visual disturbances, cardiac disturbances like QT prolongation, seizures, coma.

Treatment: Supportive care, activated charcoal if within 1 hour of ingestion, and management of cardiac arrhythmias; specific antidote not available.

Storage and Handling

Storage: Store at room temperature away from light and moisture.

Stability: Stable under recommended storage conditions.