Trimethoprim / Sulfamethoxazole (Bactrim / Septra)

Antibiotic (Sulfonamide + Dihydrofolate Reductase Inhibitor)

Dosing & Administration

Adult Dose

1 DS tablet (800/160 mg) PO BID. PCP treatment: 15-20 mg/kg/day (based on TMP) divided every 6-8 hrs.

Pediatric Dose

8-12 mg/kg/day (based on TMP) divided every 12 hrs.

Renal Adjustment

CrCl 15-30: Decrease dose by 50%. CrCl < 15: Avoid if possible.

Hepatic Adjustment

Avoid in severe liver disease.

Safety & Special Populations

Pregnancy Category

D - Avoid in 1st trimester (folate antagonism) and near term (kernicterus).

Lactation Safety

Avoid in nursing mothers with ill/premature/G6PD deficient infants.

Contraindications & Adverse Effects

Contraindications

  • Sulfa allergy
  • Megaloblastic anemia due to folate deficiency
  • Infants < 2 months old

Common Adverse Effects

  • Stevens-Johnson Syndrome (SJS)
  • Hyperkalemia
  • Bone marrow suppression
  • Crystalluria