From the Guidelines
Hydroxychloroquine is primarily used to treat malaria, lupus erythematosus, and rheumatoid arthritis, with a recommended daily dosage of ≤5 mg/kg/day actual body weight to minimize the risk of ocular toxicity. The medication has been shown to be effective in reducing inflammation through several mechanisms, including interference with lysosomal activity, inhibition of toll-like receptors, and reduction of cytokine production 1. For autoimmune conditions like lupus and rheumatoid arthritis, the usual dose is 200-400mg daily, with effects often taking weeks to months to become fully apparent.
Some of the key uses of Hydroxychloroquine include:
- Treatment of malaria, typically dosed at 400mg weekly for prevention or 800mg initially followed by 400mg at 6,24, and 48 hours for acute treatment
- Treatment of lupus erythematosus (both systemic and discoid forms)
- Treatment of rheumatoid arthritis
- Treatment of steroid-refractory chronic graft-versus-host disease (cGVHD), with a reported overall response rate (ORR) of 53% in a phase II trial involving 40 patients treated with hydroxychloroquine at 800 mg (12 mg/kg) per day 1
It is essential to note that long-term use of Hydroxychloroquine requires regular eye examinations, as it can cause retinopathy in rare cases, with a risk of retinal toxicity <2% for usage up to 10 years at a daily dosage of ≤5 mg/kg/day actual body weight 1. The medication should be taken with food to minimize stomach upset, and patients should report any visual changes immediately. Despite controversy during the COVID-19 pandemic, hydroxychloroquine is not currently recommended for COVID-19 treatment as clinical trials did not demonstrate benefit.
In terms of monitoring, baseline testing is advised to rule out confounding disease when a patient is started on Hydroxychloroquine, and annual screening with sensitive tests should begin no more than 5 years after treatment initiation 1. Effective communication among prescribing physicians, patients, and eye care providers will optimize the utility and safety of Hydroxychloroquine.
From the FDA Drug Label
Hydroxychloroquine sulfate tablets are an antimalarial and antirheumatic indicated for the: Treatment of uncomplicated malaria due to Plasmodium falciparum, Plasmodium malariae, Plasmodium ovale, and Plasmodium vivax in adult and pediatric patients. Prophylaxis of malaria in geographic areas where chloroquine resistance is not reported in adult and pediatric patients. Treatment of rheumatoid arthritis in adults. Treatment of systemic lupus erythematosus in adults. Treatment of chronic discoid lupus erythematosus in adults.
The uses of Hydroxychloroquine (Plaquenil) are:
- Treatment of uncomplicated malaria due to certain Plasmodium species in adults and pediatric patients
- Prophylaxis of malaria in areas where chloroquine resistance is not reported
- Treatment of rheumatoid arthritis in adults
- Treatment of systemic lupus erythematosus in adults
- Treatment of chronic discoid lupus erythematosus in adults 2 2
From the Research
Uses of Hydroxychloroquine (Plaquenil)
Hydroxychloroquine (HCQ) is used for the management of various systemic autoimmune diseases, including:
- Systemic lupus erythematosus: HCQ therapy reduces activity, the accrual of organ damage, risk of infections and thrombosis, and improves the cardiometabolic profile 3
- Rheumatoid arthritis: HCQ improves cardiometabolic risk and has a favorable effect on joint inflammation 3, 4
- Sjögren's syndrome: HCQ increases lacrimal quality and improves objective and subjective inflammatory markers 3
- Antiphospholipid Syndrome: HCQ is effective in primary and secondary thrombosis prevention 3, 4
- Dermatomyositis: HCQ may improve dermatological manifestations 3
- Sarcoidosis and Still disease: HCQ may have positive effects in treatment 3, 5
Mechanisms of Action
HCQ has immunomodulatory, hypolipidemic, hypoglycemic, and antithrombotic properties, and diminishes the risk of malignancies 3. Its mechanisms of action include:
- Reducing inflammatory pathways
- Toll-like receptors activation
- Suppressing T-cell and B-cell hyperactivity
- Reducing pro-inflammatory cytokine gene expression 3, 5
Safety Profile
HCQ is generally considered safe, but adverse reactions have been reported, including retinal toxicity, which can be potentially severe 3, 4, 6. Careful dose monitoring and regular ocular examinations can reduce the risk of retinopathy 6.