- Treatment of uncomplicated Plasmodium falciparum malaria
- Often used in combination with artesunate in artemisinin-based combination therapy (ACT)
Adult Dosing (when used with artesunate):
- Sulfamethoxypyrazine 500 mg + Pyrimethamine 25 mg OD for 3 days
- Usually co-administered with Artesunate 100 mg OD for 3 days
Pediatric Dosing:
- Weight-based dosing in fixed-dose combinations
- For example:
- 250 mg sulfamethoxypyrazine + 12.5 mg pyrimethamine (per tablet) for smaller children
- Dose given OD for *3/7
Common tablet formulations:
- Sulfamethoxypyrazine 500 mg + Pyrimethamine 25 mg
- Pediatric strengths: 250 mg + 12.5 mg
- Available as fixed-dose combinations or as part of SP-Artesunate combinations
- Administer once daily (OD) for 3 consecutive days
- Should be taken with food to reduce gastrointestinal discomfort
- Ensure adequate hydration to minimize risk of crystalluria from the sulfonamide component
Class:
- Sulfamethoxypyrazine: Sulfonamide (antifolate)
- Pyrimethamine: Diaminopyrimidine (antifolate)
Mechanism of Action:
- Sulfamethoxypyrazine inhibits dihydropteroate synthase, blocking folate synthesis
- Pyrimethamine inhibits dihydrofolate reductase, further blocking folate utilization
- The dual blockade disrupts DNA synthesis in the malaria parasite
Pharmacokinetics:
- Sulfamethoxypyrazine: Long half-life (~100 hours), allowing once-daily dosing
- Pyrimethamine: Long half-life (~96 hours); good oral absorption
- Nausea, vomiting, abdominal pain
- Skin rash, urticaria
- Rare but serious: Stevens-Johnson syndrome, toxic epidermal necrolysis
- Bone marrow suppression (with high or prolonged use): anemia, thrombocytopenia
- Hepatotoxicity (rare)
- Hypersensitivity to sulfonamides or pyrimethamine
- History of severe skin reactions to sulfa drugs
- Megaloblastic anemia due to folate deficiency
- Additive toxicity with other antifolates (e.g., co-trimoxazole)
- Anticonvulsants (phenytoin): pyrimethamine may displace protein binding
- May interact with methotrexate (increased antifolate effects)
Drug Status
Availability | |
Pregnancy | |
Breastfeeding | |
Schedule |
BRAND NAME | STRENGTH | FORMULATION | PACK SIZE | MANUFACTURER | DISTRIBUTOR |
---|---|---|---|---|---|
Ekelfin | 500mg/25mg | Tablet | 2’s | Elys Chemicals | Elys Chemicals |
Laefin | 500mg/25mg | Tablet | 2’s | Laboratory & Allied | Laboratory & Allied |
Malafin | 500mg/25mg | Tablet | 30’s | Universal Corporation | Universal Corporation |