Hydroxychloroquine Drug Profile

What is Hydroxychloroquine?

Hydroxychloroquine is an antimalarial medication that belongs to a class of drugs called 4-aminoquinoline compounds. Originally developed for preventing and treating malaria, it is also widely used to treat autoimmune conditions such as rheumatoid arthritis and lupus. The medication works by interfering with cellular processes in both parasites and immune cells.

Uses

Hydroxychloroquine has several established medical uses:

• Malaria prevention and treatment: Used to prevent malaria in travelers to endemic areas and treat certain types of malaria infections, particularly those caused by Plasmodium vivax and Plasmodium ovale.
• Rheumatoid arthritis: Helps reduce joint inflammation, pain, and swelling in patients with this chronic autoimmune condition.
• Systemic lupus erythematosus (SLE): Manages symptoms of lupus, including skin rashes, joint pain, and fatigue, while helping prevent disease flares.
• Discoid lupus erythematosus: Treats the skin manifestations of this form of lupus, helping to reduce characteristic skin lesions.
• Sjögren’s syndrome: Sometimes prescribed off-label to help manage symptoms of this autoimmune condition affecting tear and saliva production.

How it works

Hydroxychloroquine works through multiple mechanisms depending on its use. In malaria, it interferes with the parasite’s ability to break down hemoglobin in red blood cells, leading to toxic buildup that kills the parasite. For autoimmune conditions, it modulates the immune system by altering pH levels in cellular compartments and interfering with antigen presentation, which helps reduce inappropriate immune responses that cause inflammation and tissue damage.

Side effects

Common side effects:

Submit Your Paper

• Nausea and stomach upset
• Diarrhea
• Headache
• Dizziness
• Skin rash
• Loss of appetite
• Mood changes or irritability
• Hair color changes or hair loss

Serious side effects requiring immediate medical attention:

• Vision changes or eye problems (retinal damage)
• Severe muscle weakness
• Hearing loss or ringing in ears
• Heart rhythm abnormalities
• Signs of liver problems (yellowing of skin or eyes, dark urine)

Warnings and precautions

• Eye monitoring required: Regular ophthalmologic examinations are essential as the drug can cause irreversible retinal damage, particularly with long-term use or high doses.
• Heart conditions: Should be used cautiously in patients with heart rhythm disorders, as hydroxychloroquine can prolong QT interval and potentially cause dangerous arrhythmias.
• Pregnancy and breastfeeding: Generally considered safe during pregnancy for established indications like lupus, but should only be used when benefits outweigh risks and under medical supervision.
• Liver and kidney disease: Dosage adjustments may be necessary in patients with impaired liver or kidney function, as the drug is metabolized by the liver and eliminated through the kidneys.
• G6PD deficiency: Can cause severe hemolysis in patients with glucose-6-phosphate dehydrogenase deficiency, so screening may be recommended before starting treatment.

Interactions

• Digoxin: Hydroxychloroquine can increase digoxin levels, potentially leading to toxicity and requiring dose monitoring.
• Insulin and diabetes medications: May enhance blood sugar-lowering effects, increasing risk of hypoglycemia.
• Antacids and kaolin: Can reduce absorption of hydroxychloroquine; separate administration by at least 2 hours.
• QT-prolonging drugs: Combining with other medications that affect heart rhythm (like certain antibiotics, antiarrhythmics) increases risk of dangerous heart rhythm abnormalities.
• Cyclosporine: Hydroxychloroquine may increase cyclosporine levels, requiring monitoring and possible dose adjustments.
• Methotrexate: May increase methotrexate levels and toxicity risk when used together for autoimmune conditions.
• Tamoxifen: Concurrent use may increase risk of retinal toxicity.
• Live vaccines: May reduce effectiveness of live vaccines due to antimalarial effects.

Check interactions with the GMJ Interaction Checker

Dosage

Typical adult dosages vary significantly based on the condition being treated:

• Malaria prevention: 400 mg once weekly, starting 1-2 weeks before travel and continuing for 4 weeks after leaving endemic area
• Malaria treatment: Initial dose of 800 mg, followed by 400 mg at 6, 24, and 48 hours
• Rheumatoid arthritis/lupus: 200-400 mg daily, typically starting with higher doses and reducing to maintenance levels

Dosages should always be individualized based on body weight, kidney function, and specific medical conditions. Your healthcare provider will determine the appropriate dose and duration of treatment for your specific situation.

Sources: FDA DailyMed drug labels (public domain), BNF, WHO Essential Medicines List. This article is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider before starting or stopping any medication.

This work is licensed under Creative Commons Attribution 4.0 International (CC BY 4.0). You are free to share and adapt this content with attribution to GMJ News (news.gmj.ge).