What is the recommended dose of hydroxychloroquine (HCQ) for rheumatoid arthritis (RA)?

Hydroxychloroquine Dosing for Rheumatoid Arthritis

The recommended dose of hydroxychloroquine for rheumatoid arthritis is ≤5.0 mg/kg of actual body weight daily (maximum 400 mg daily), which provides a low risk of retinal toxicity while maintaining therapeutic efficacy. 1

Dosing Guidelines

Initial Dosing

• Starting dose: 400 mg daily (can be given as a single daily dose or two divided doses) 2
• The action of hydroxychloroquine is cumulative and may require weeks to months for maximum therapeutic effect 2

Maintenance Dosing

• Chronic dosage: 200-400 mg daily (as a single dose or two divided doses) 2
• Daily doses exceeding 5 mg/kg of actual body weight significantly increase the risk of retinopathy 1, 2

Risk Assessment for Retinopathy

The risk of retinal toxicity is determined by:

1. Daily dose relative to body weight: Primary risk factor

   • ≤5.0 mg/kg/day based on actual body weight provides low risk (<2% with up to 10 years of use) 1
   • Higher doses increase risk to ~10% after 10 years 1

2. Duration of treatment: Risk increases with longer use

   • For patients with normal screening examination, annual risk remains <5% even after 20 years of use 1

3. Additional risk factors:

   • Renal insufficiency (HCQ is excreted in urine) 1
   • Concomitant use of tamoxifen 1
   • Pre-existing retinal or macular disease 1

Special Considerations

• Administration: Take with food or milk to improve tolerability 2
• Do not crush or divide tablets 2
• Renal impairment: Patients with reduced renal function may need lower doses and closer monitoring 1
• Monitoring: Regular ophthalmologic screening is recommended for patients on long-term therapy 1

Clinical Efficacy

• Hydroxychloroquine is conditionally recommended over other conventional synthetic DMARDs for DMARD-naive patients with low disease activity 1
• It can be used as monotherapy or in combination with other antirheumatic agents 2
• Corticosteroids, salicylates, and other antirheumatic agents may be used concomitantly with hydroxychloroquine 2

Safety Considerations

• Hydroxychloroquine is considered safe at proper doses in conjunction with appropriate eye screening 1
• The risk of toxicity is very low for doses below 5 mg/kg of actual body weight 1
• Cardiotoxicity, including cardiomyopathy and QT prolongation, has been reported in rare cases 2
• Avoid use in patients with known hypersensitivity to 4-aminoquinoline compounds 2

Practical Dosing Algorithm

1. Calculate maximum daily dose based on actual body weight:

   • Maximum dose = 5 mg/kg/day (not to exceed 400 mg daily)
   • Example: 70 kg patient → 350 mg daily maximum

2. Typical dosing schedule:

   • Initial: 400 mg daily for 4-12 weeks to achieve therapeutic effect
   • Maintenance: Adjust to 200-400 mg daily based on response

3. Monitor efficacy and adjust as needed:

   • If good response is achieved, continue maintenance dose
   • If inadequate response after 3-6 months, consider adding or switching to other DMARDs

Remember that hydroxychloroquine should not be avoided due to fear of retinopathy, as it is a valuable medication for RA when properly dosed and monitored.