What are the contraindications for primaquine?

Contraindications of Primaquine

Primaquine is absolutely contraindicated in patients with severe G6PD deficiency, pregnant women, and acutely ill patients with systemic diseases causing granulocytopenia (such as rheumatoid arthritis or lupus erythematosus). 1

Absolute Contraindications

1. Severe G6PD Deficiency

• G6PD testing must be performed before prescribing primaquine 2, 1
• Primaquine causes dose-dependent hemolytic anemia in G6PD-deficient individuals, which can be life-threatening 2, 1
• The risk is highest in patients with severe deficiency (particularly the Mediterranean B- variant) 3
• If severe G6PD deficiency is confirmed, primaquine must not be used 1

Critical Pitfall: G6PD deficiency is highly prevalent in malaria-endemic regions including Africa, Southern Europe, Mediterranean region, Middle East, South-East Asia, and Oceania 1. Never assume normal G6PD status based on ethnicity alone.

2. Pregnancy

• Primaquine is absolutely contraindicated throughout pregnancy 2, 1
• The drug crosses the placenta and can cause hemolytic anemia in a G6PD-deficient fetus, even if the mother is G6PD-normal 2, 1
• When radical cure is needed during pregnancy, substitute with weekly chloroquine until delivery, then reassess primaquine use postpartum 2
• Pregnancy testing is required for sexually-active females of reproductive potential before starting primaquine 1

3. Systemic Diseases with Granulocytopenia

• Contraindicated in acutely ill patients with rheumatoid arthritis or lupus erythematosus when these conditions manifest with granulocytopenia 1
• These conditions increase the risk of bone marrow suppression

4. Concurrent Use of Specific Medications

• Quinacrine (mepacrine) is absolutely contraindicated with primaquine - quinacrine potentiates primaquine toxicity 1
• Do not give primaquine to patients who recently received quinacrine 1
• Avoid concurrent use with other potentially hemolytic drugs or bone marrow depressants 1

Relative Contraindications and Special Precautions

Mild to Moderate G6PD Deficiency

• Not an absolute contraindication, but requires careful risk-benefit assessment 1
• If primaquine is used:
  • Check baseline hemoglobin and hematocrit before treatment 1
  • Perform close hematological monitoring (e.g., days 3 and 8) 1
  • Ensure adequate medical support is available to manage potential hemolysis 1
  • Consider weekly dosing regimen (0.75 mg/kg/week for 8 weeks) in areas where G6PD testing is unavailable 4

Breastfeeding

• Recent evidence (2018) demonstrates primaquine is safe during breastfeeding 5, 6
• Primaquine concentrations in breast milk are very low (~0.6% of maternal dose) 5
• Infant exposure is minimal and unlikely to cause hemolysis even in G6PD-deficient infants 5, 6
• The 1990 guidelines 2 suggested caution, but newer data 5, 6 support safe use without discontinuing nursing

Unknown G6PD Status

• When G6PD testing is unavailable, assess risk factors for G6PD deficiency or favism 1
• If primaquine must be used:
  • Check baseline hemoglobin/hematocrit 1
  • Implement close hematological monitoring (days 3 and 8) 1
  • Ensure medical support for managing potential hemolysis 1

Monitoring Requirements When Primaquine is Used

• Discontinue immediately if signs of hemolysis appear: darkening of urine, marked fall in hemoglobin or red blood cell count 1
• Baseline and serial hemoglobin/hematocrit measurements are mandatory 1
• Adequate medical facilities must be available to manage hemolytic complications 1

Contraception Requirements

• Females of childbearing potential: Use effective contraception during treatment and until completion of next menstrual cycle 1
• Males with partners who may become pregnant: Use condoms during treatment and for 3 months after stopping primaquine 1