Hydroxychloroquine

1. Introduction

Hydroxychloroquine is a disease-modifying antirheumatic drug (DMARD) and antimalarial agent used to treat autoimmune disorders and malaria. It reduces inflammation in autoimmune conditions by modulating immune responses and suppresses the activity of malarial parasites by interfering with their metabolism.

2. Indications

  • Approved Indications:
    • Rheumatoid arthritis (RA).
    • Systemic lupus erythematosus (SLE).
    • Discoid lupus erythematosus (DLE).
    • Malaria (prophylaxis and treatment).
  • Off-Label Uses:
    • Sjögren’s syndrome.
    • Dermatomyositis.
    • Antiphospholipid syndrome (APS).

3. Dosage

  • Adults:
    • Rheumatoid Arthritis/SLE: 200–400 mg once daily or in divided doses.
    • Malaria Prophylaxis: 400 mg once weekly (starting 1–2 weeks before travel and continuing for 4 weeks after returning).
    • Malaria Treatment: 800 mg as an initial dose, followed by 400 mg at 6, 24, and 48 hours.
  • Children (for malaria):
    • 6.5 mg/kg/day based on actual body weight, not exceeding 400 mg daily.
  • Elderly:
    • Use cautiously and adjust dose based on renal function.

4. Administration

  • Take orally with food or milk to reduce gastrointestinal upset.
  • Ensure regular dosing for chronic conditions (RA, SLE) to maintain symptom control.

5. Forms Available

  • Tablets: 200 mg, 400 mg.

6. Side Effects

6.1. Common Side Effects

  • Nausea.
  • Diarrhoea.
  • Abdominal cramps.
  • Headache.

6.2. Less Common Side Effects

  • Skin rashes or itching.
  • Loss of appetite.
  • Mood changes (e.g., irritability, nervousness).

6.3. Rare but Serious Side Effects

  • Retinal toxicity (irreversible damage to the retina with long-term use).
  • Cardiotoxicity (QT prolongation, arrhythmias).
  • Myopathy or neuromyopathy (muscle weakness).

7. Warnings

  • Retinal Toxicity: Long-term use may lead to irreversible retinal damage. Patients should undergo regular eye exams.
  • Cardiotoxicity: Use cautiously in patients with pre-existing heart conditions or those on QT-prolonging drugs.
  • Hypoglycaemia: May cause severe hypoglycaemia even in non-diabetic patients.

8. Precautions

  • Use cautiously in patients with:
    • G6PD deficiency (increased risk of haemolysis).
    • Hepatic or renal impairment (dose adjustments may be necessary).
    • Psoriasis (may exacerbate skin lesions).

9. Interactions

  • Drug-Drug Interactions:
    • QT-prolonging drugs (e.g., amiodarone, azithromycin): Increased risk of cardiac arrhythmias.
    • Antiepileptics: May lower seizure threshold.
    • Digoxin: Increases serum levels of digoxin.
    • Antacids: Decrease absorption; take hydroxychloroquine 2 hours before or after antacids.
  • Drug-Food Interactions:
    • Grapefruit juice may enhance adverse effects; avoid consumption.

10. Monitoring Parameters

  • Before Initiation:
    • Baseline ophthalmologic examination (visual acuity, retinal screening).
    • Baseline ECG in patients with cardiac risk factors.
    • Liver and renal function tests.
  • During Treatment:
    • Annual eye exams (more frequent in high-risk patients).
    • Blood tests for liver and kidney function.
    • Monitor for muscle weakness or unusual symptoms.

11. Use in Children

  • Approved for use in children for malaria treatment and prophylaxis. Doses should be carefully adjusted based on weight.

12. Use in Pregnancy

  • Category C: May be used if the benefits outweigh risks, particularly in lupus or other autoimmune conditions. Limited data suggest it is relatively safe, but consultation with a specialist is recommended.

13. Use in Elderly

  • Use cautiously, particularly in patients with impaired renal function or those at risk of cardiac toxicity.

14. Use in Kidney Disease

  • Dose reduction may be required in moderate-to-severe renal impairment. Monitor renal function periodically.

15. Use in Liver Disease

  • Use cautiously in hepatic impairment, as hydroxychloroquine is metabolised in the liver.

16. Patient Counselling Points

  • Take hydroxychloroquine with food or milk to minimise stomach upset.
  • Report any changes in vision, such as blurriness or difficulty seeing, to your doctor immediately.
  • Avoid grapefruit juice and antacids close to your dose, as they may affect the medication’s effectiveness.
  • Attend regular eye exams and follow-ups as prescribed.
  • Inform your doctor of any unusual symptoms, such as muscle weakness, severe fatigue, or abnormal heart rhythms.
  • For malaria prophylaxis, adhere strictly to the dosing schedule, including doses after leaving the malarial area.

17. Table of Brand Names, Manufacturers, and Prices

Brand NameManufacturerPrice (USD)
PlaquenilSanofi$20–50 (30 tablets, 200 mg)
Generic HydroxychloroquineVarious manufacturers$10–25 (30 tablets, 200 mg)

18. FAQs (15 Questions)

  1. What is hydroxychloroquine used for?
    It is used to treat rheumatoid arthritis, lupus, and malaria.
  2. How does hydroxychloroquine work?
    It reduces inflammation in autoimmune diseases and interferes with parasite metabolism in malaria.
  3. How long does it take for hydroxychloroquine to work?
    For autoimmune diseases, it may take 4–8 weeks to show noticeable effects.
  4. Can hydroxychloroquine cause side effects?
    Yes, common side effects include nausea, headache, and skin rash. Serious effects include retinal toxicity and heart problems.
  5. Is hydroxychloroquine safe during pregnancy?
    It can be used if the benefits outweigh risks, particularly for lupus or rheumatoid arthritis.
  6. Can hydroxychloroquine cause vision problems?
    Yes, prolonged use can cause retinal damage. Regular eye exams are required.
  7. Can I stop hydroxychloroquine suddenly?
    No, always consult your doctor before discontinuing to prevent disease flare-ups.
  8. Can children take hydroxychloroquine?
    Yes, it is approved for malaria treatment and prophylaxis in children with weight-adjusted dosing.
  9. Does hydroxychloroquine interact with other medications?
    Yes, it interacts with QT-prolonging drugs, antacids, and digoxin, among others.
  10. How should hydroxychloroquine be stored?
    Store at room temperature, away from light and moisture.
  11. Can hydroxychloroquine prevent COVID-19?
    No, hydroxychloroquine is not recommended for COVID-19 prevention or treatment.
  12. Can I drink alcohol while taking hydroxychloroquine?
    Yes, but moderation is advised to avoid exacerbating liver-related side effects.
  13. Can hydroxychloroquine cause hair loss?
    Rarely, hair thinning or loss may occur, particularly in autoimmune conditions.
  14. What should I do if I miss a dose?
    Take it as soon as you remember, but skip it if it is close to the next dose. Do not double up.
  15. How often should I have eye exams while on hydroxychloroquine?
    Annual exams are recommended, with more frequent monitoring for high-risk patients.