Hydroxychloroquine Side Effects and Monitoring

Ocular Toxicity

Retinopathy can progress even after drug discontinuation, making early detection critical, particularly in patients with cumulative dosage and treatment duration risks 1
Asian patients typically show extramacular damage near the arcades, while European-descent patients show parafoveal involvement 1
Corneal deposits (verticillata) can occur but are reversible and not associated with vision loss 1
Maximum safe daily doses: chloroquine 250 mg/day; hydroxychloroquine doses exceeding these thresholds increase irreversible retinopathy risk 2

ECG abnormalities include widening of QRS interval, T-wave changes, and bundle branch blocks 2
Toxic myopathy, peripheral neuropathy (improves with prompt withdrawal) 2
Gastrointestinal upset, headache, visual disturbances, urticaria, and pruritus with oral therapy 2
Skin hyperpigmentation, discoloration of nail beds and mucous membranes 2
Hair bleaching in blonde and red-haired individuals 2

CYP2D6 and P-glycoprotein inhibition: intensified monitoring needed with gefitinib and tamoxifen 3, 4
Additive QT prolongation risk with multiple cancer drugs (cabozantinib, ceritinib, crizotinib, nilotinib, osimertinib, vandetanib, vemurafenib, oxaliplatin, arsenic trioxide) 3, 4
Contraindicated with ondansetron >8mg, domperidone, and citalopram due to torsades de pointes risk 3, 4
Peripheral neuropathy risk increases when combined with platinum salts, anthracyclines, taxanes, immunomodulators, especially with diabetes or alcohol abuse 3, 4
D-penicillamine and cimetidine lead to higher hydroxychloroquine levels 2
Pregnancy category C 2
Has been used safely in 133 pregnancies with connective tissue disease, showing no difference in live birth rates or complications compared to untreated patients 2
Associated with decreased lupus activity without fetal harm 5
Limited safety information available in pediatrics, though antimalarial agents have been used for rheumatologic diseases in children for many years 2