Hydroxychloroquine is an oral disease-modifying antirheumatic drug (DMARD) with immunomodulatory properties, primarily indicated for autoimmune disorders and malaria prophylaxis. As a 4-aminoquinoline derivative, it alters lysosomal pH and inhibits antigen presentation, providing sustained control of inflammatory pathways. Its well-established safety profile and oral administration make it a cornerstone therapy in rheumatology and dermatology.

Features

• Chemical class: 4-Aminoquinoline compound
• Available formulations: 200mg and 400mg oral tablets
• Mechanism: Lysosomal alkalinization and Toll-like receptor inhibition
• Half-life: Approximately 40 days
• Metabolism: Hepatic via CYP2D6, CYP3A4, CYP2C8
• Excretion: Renal (50%) and fecal (25%)
• Pregnancy category: FDA Category C (requires risk-benefit assessment)

Benefits

• Provides long-term suppression of autoimmune activity through immunomodulation
• Reduces disease flares and progression in rheumatic conditions
• Offers chemoprophylaxis against malaria in endemic regions
• Demonstrates corticosteroid-sparing effects in inflammatory disorders
• Improves quality of life through sustained symptom control
• Shows favorable long-term safety profile with appropriate monitoring

Common use

Hydroxychloroquine is FDA-approved for treatment of uncomplicated malaria, rheumatoid arthritis, systemic lupus erythematosus, and chronic discoid lupus erythematosus. Off-label applications include Sjögren’s syndrome, porphyria cutanea tarda, and certain dermatological conditions. Rheumatologists, dermatologists, and infectious disease specialists prescribe it as monotherapy or in combination regimens based on disease severity and patient response.

Dosage and direction

Dosing is weight-based (≤6.5 mg/kg actual body weight daily) to minimize retinal toxicity risk. For rheumatoid arthritis and lupus: 200-400 mg daily. Malaria prophylaxis: 400 mg weekly starting 1-2 weeks before exposure and continuing 4 weeks post-exposure. Administer with food or milk to reduce gastrointestinal discomfort. Regular ophthalmologic screening (baseline and annual after 5 years) is mandatory due to cumulative dose-related retinopathy risk.

Precautions

Regular monitoring includes complete blood count, liver function tests, and glucose-6-phosphate dehydrogenase (G6PD) levels. Cardiologists should evaluate patients with pre-existing cardiac conditions due to potential QT prolongation. Psychiatric history requires assessment as mood changes may occur. Dermatological photosensitivity necessitates sun protection measures. Pediatric use requires careful weight-based dosing and growth monitoring.

Contraindications

Absolute contraindications include known hypersensitivity to 4-aminoquinoline compounds, pre-existing retinal field changes, and concurrent use with other retinotoxic medications. Relative contraindications include severe hepatic impairment, psoriasis (may exacerbate), porphyria, and myasthenia gravis. G6PD deficiency requires careful risk-benefit analysis due to hemolysis risk.

Possible side effects

Common reactions (≥1%): gastrointestinal distress (nausea, diarrhea, abdominal cramps), headache, and dermatological reactions (pruritus, pigmentary changes). Serious adverse effects include irreversible retinopathy (dose-dependent), cardiomyopathy, QT prolongation, hematologic abnormalities (agranulocytosis, aplastic anemia), and severe hypoglycemia. Neuropsychiatric effects (anxiety, nightmares, psychosis) occur rarely but require immediate evaluation.

Drug interaction

Significant interactions occur with:

• Digoxin (increased levels)
• Insulin and oral hypoglycemics (enhanced effects)
• CYP2D6 substrates (altered metabolism)
• QT-prolonging agents (additive cardiac risk)
• Antacids and kaolin (reduced absorption)
• Methotrexate (increased toxicity risk)
• Tamoxifen (reduced efficacy)

Missed dose

If a daily dose is missed, take it as soon as remembered unless near next scheduled dose. Never double doses. For weekly malaria prophylaxis: take immediately upon recall, then resume regular weekly schedule. Maintain consistent timing to ensure stable plasma concentrations. Document missed doses for toxicity risk assessment.

Overdose

Acute overdose (≥30mg/kg) constitutes a medical emergency presenting with headache, visual disturbances, cardiovascular collapse, hypokalemia, and convulsions. Management includes immediate gastric lavage, activated charcoal, ECG monitoring, and supportive care. Forced diuresis and acidification of urine may enhance elimination. Cardiac monitoring must continue for ≥24 hours due to prolonged half-life.

Storage

Store at controlled room temperature (20-25°C/68-77°F) in original container protected from light and moisture. Keep tightly closed and away from children. Do not transfer to pill organizers without humidity protection. Discard expired medication through pharmaceutical take-back programs. Avoid freezing or excessive heat.

Disclaimer

This information does not replace professional medical advice. Consult qualified healthcare providers for diagnosis and treatment decisions. Individual patient factors may alter risk-benefit considerations. Regulatory approvals vary by jurisdiction; prescribers must follow local guidelines.

Reviews

Clinical studies demonstrate 60-70% response rates in rheumatoid arthritis over 6 months, with ACR20 improvement scores averaging 55%. Lupus trials show 50% reduction in flare frequency versus placebo. Malaria prophylaxis efficacy exceeds 90% in chloroquine-sensitive regions. Long-term observational data confirms maintained efficacy over decades with appropriate monitoring. Patient-reported outcomes indicate significant improvement in fatigue and joint mobility scores.