Chloroquine

# Chloroquine ## Overview - **Classification**: Antimalarial, Amoebicide, Disease-Modifying Antirheumatic Drug (DMARD) - **Mechanism**: Concentrates in parasite food vacuoles, interfering with heme detoxification. Also exhibits immunomodulatory effects. ## Primary Indications 1. **Treatment of Uncomplicated Malaria**: Due to chloroquine-sensitive *P. falciparum*, *P. vivax*, *P. ovale*, and *P. malariae*. 2. **Malaria Prophylaxis**: In areas with chloroquine-sensitive malaria. 3. **Extraintestinal Amebiasis**: Alternative treatment for amebic liver abscess. 4. **Rheumatoid Arthritis & Systemic Lupus Erythematosus**: Used as an immunomodulator (less common than hydroxychloroquine). ## Adult Dosing ### Standard Dosing **Uncomplicated Malaria Treatment (Chloroquine-sensitive)** - **Dose**: **600 mg chloroquine base** (equivalent to 1000 mg chloroquine phosphate) - **Frequency**: Initial dose, then **300 mg chloroquine base** (500 mg chloroquine phosphate) at 6, 24, and 48 hours later. - **Route**: Oral (PO) - **Duration**: Total **1500 mg chloroquine base** over 3 days. **Malaria Prophylaxis** - **Dose**: **300 mg chloroquine base** (equivalent to 500 mg chloroquine phosphate) - **Frequency**: Once weekly - **Route**: Oral (PO) - **Duration**: Start 1-2 weeks before, continue during, and 4 weeks after leaving endemic area. **Extraintestinal Amebiasis** - **Dose**: **600 mg chloroquine base** (1000 mg chloroquine phosphate) daily for 2 days. - **Frequency**: Followed by **300 mg chloroquine base** (500 mg chloroquine phosphate) daily for 2-3 weeks. - **Route**: Oral (PO) ### Dose Adjustments - **Renal Impairment**: - CrCl < 10 mL/min: Reduce dose by 50%. - CrCl 10-50 mL/min: Reduce dose by 25%. - For prophylaxis: Consider alternative if CrCl < 30 mL/min. - **Hepatic Impairment**: Use with caution in severe liver disease; monitor for toxicity. - **Elderly Patients**: Increased risk of adverse effects; consider lower doses or extended intervals, especially with renal impairment. ## Pediatric Dosing (all doses in mg chloroquine base) ### Neonates (0-28 days) - **Special Notes**: Limited data; generally follows infant guidelines with extreme caution and close monitoring. Malaria prophylaxis not typically recommended for infants < 4.5 kg. ### Infants (1-12 months) **Malaria Treatment (Chloroquine-sensitive)** - **Initial Dose**: **10 mg/kg** PO. Max **600 mg**. - **Frequency**: At 0 hours (initial), then **5 mg/kg** PO at 6, 24, and 48 hours later. - **Maximum Total**: **25 mg/kg** over 3 days (Max **1500 mg** total). **Malaria Prophylaxis** - **Dose**: **5 mg/kg** PO - **Frequency**: Once weekly - **Maximum**: **300 mg** per week. - **Special Notes**: Crush tablets and mix with food/liquid. Ensure accurate weighing for dose. ### Children (1-12 years) **Malaria Treatment (Chloroquine-sensitive)** - **Initial Dose**: **10 mg/kg** PO. Max **600 mg**. - **Frequency**: At 0 hours (initial), then **5 mg/kg** PO at 6, 24, and 48 hours later. - **Maximum Total**: **25 mg/kg** over 3 days (Max **1500 mg** total). **Malaria Prophylaxis** - **Dose**: **5 mg/kg** PO - **Frequency**: Once weekly - **Maximum**: **300 mg** per week. - **Special Notes**: Ensure accurate weighing for dose. ### Adolescents (13-18 years) **Malaria Treatment (Chloroquine-sensitive)** - **Dose**: Apply **adult dosing** regimen. - **Maximum**: **1500 mg** total over 3 days. **Malaria Prophylaxis** - **Dose**: Apply **adult dosing** regimen. - **Maximum**: **300 mg** per week. ## Safety Information ### Contraindications - **Absolute**: Chloroquine-induced retinal or visual field changes. - **Absolute**: Porphyria. - **Absolute**: Psoriasis (may exacerbate). - **Relative**: Hypersensitivity to chloroquine. ### Common Adverse Effects - **Very Common (>10%)**: Nausea, vomiting, diarrhea, abdominal cramps, headache. - **Common (1-10%)**: Dizziness, blurred vision, pruritus, skin rash, QTc prolongation (dose-dependent). - **Serious but Rare**: Retinopathy (irreversible vision loss with long-term/high dose), cardiomyopathy, seizures, blood dyscrasias, suicidal ideation. ### Key Drug Interactions - **QTc prolonging drugs (e.g., Amiodarone, Fluoroquinolones)**: Increased risk of Torsades de Pointes. Avoid co-administration. - **Antacids/Kaolin**: Reduce chloroquine absorption. Separate administration by at least **4 hours**. - **Mefloquine**: Increased risk of convulsions and cardiac arrest. Avoid co-administration for prophylaxis. - **Cyclosporine**: May increase cyclosporine levels. Monitor cyclosporine levels closely. ## Monitoring & Follow-up - **Before Treatment**: - Baseline ophthalmologic exam (for long-term use). - Baseline ECG (if cardiac risk factors or concomitant QTc prolonging drugs). - G6PD screening (in endemic areas where G6PD deficiency is common). - **During Treatment**: - Monitor for visual disturbances (blurred vision, difficulty focusing). - Monitor for GI upset (administer with food/milk). - ECG monitoring (if high dose, IV, or risk factors for QTc prolongation). - **Clinical Signs**: Watch for severe headache, muscle weakness, hearing loss, skin changes, mood changes. ## Clinical Pearls - 💡 **Chloroquine resistance** is widespread for *P. falciparum*; always confirm local susceptibility before use. - 💡 Administer with **food or milk** to reduce gastrointestinal upset and improve tolerability. - 💡 **Ocular toxicity** (retinopathy) is a major concern with prolonged use; annual ophthalmologic exams are crucial. - 💡 For prophylaxis, start **1-2 weeks before** travel and continue for **4 weeks after** leaving the endemic area. - 💡 All doses are based on **chloroquine base**. Pay attention to formulations that list chloroquine phosphate. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.