Septran%25252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252520%25252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252528co-Trimoxazole%25252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252529

# Septran (Co-Trimoxazole) ## Overview Septran is a combination antibiotic containing trimethoprim and sulfamethoxazole. It is bactericidal and works by inhibiting folic acid synthesis. ## Primary Indications * Urinary tract infections (UTIs) * Pneumocystis jirovecii pneumonia (PJP) prophylaxis and treatment * Acute exacerbations of chronic bronchitis * Shigellosis ## Adult Dosing * **UTIs:** 160 mg trimethoprim/800 mg sulfamethoxazole (1 double-strength tablet) every 12 hours for 3-7 days. * **PJP Prophylaxis:** 1 double-strength tablet once daily. * **PJP Treatment:** 15-20 mg/kg trimethoprim component and 75-100 mg/kg sulfamethoxazole component per day, divided into 3-4 doses, for 14-21 days. Maximum dose: 160 mg trimethoprim/800 mg sulfamethoxazole every 6 hours. * **Shigellosis:** 160 mg trimethoprim/800 mg sulfamethoxazole every 12 hours for 5 days. ## Pediatric Dosing Dosing is typically based on the trimethoprim component (mg/kg/day). * **UTIs (12 years and older):** Same as adult dosing. * **UTIs (younger than 12 years):** 8 mg/kg trimethoprim and 40 mg/kg sulfamethoxazole per day, divided into 2 doses, for 7 days. * **PJP Prophylaxis:** 5 mg/kg trimethoprim and 25 mg/kg sulfamethoxazole per day, divided into 2 doses, given 2 days per week. * **PJP Treatment:** 15-20 mg/kg trimethoprim and 75-100 mg/kg sulfamethoxazole per day, divided into 3-4 doses, for 14-21 days. ## Dose Adjustments * **Renal Impairment (CrCl > 30 mL/min):** No adjustment needed. * **Renal Impairment (CrCl 15-30 mL/min):** Reduce usual dose by 50%. * **Renal Impairment (CrCl < 15 mL/min):** Contraindicated. ## Contraindications * Documented hypersensitivity to trimethoprim or sulfonamides. * Infants younger than 2 months (risk of kernicterus). * Severe renal or hepatic impairment. * Megaloblastic anemia due to folate deficiency. ## Adverse Effects Common: Nausea, vomiting, rash, hyperkalemia. Serious: Stevens-Johnson syndrome, toxic epidermal necrolysis, bone marrow suppression (anemia, leukopenia, thrombocytopenia), DRESS syndrome, interstitial nephritis, hyperkalemia, hypoglycemia. ## Key Drug Interactions * **Warfarin:** Increased INR. Monitor INR closely. * **ACE inhibitors/ARBs/Potassium-sparing diuretics:** Increased risk of hyperkalemia. * **Methotrexate:** Increased methotrexate toxicity. * **Potassium supplements:** Increased risk of hyperkalemia. * **Rifampin:** May decrease co-trimoxazole levels. ## Monitoring * Renal function (creatinine). * Complete blood counts (CBC), especially with prolonged therapy or in immunocompromised patients. * Electrolytes (potassium). * Signs of hypersensitivity reactions. ## Clinical Pearls * Administer oral doses with food or milk to minimize gastrointestinal upset. * Ensure adequate fluid intake to prevent crystalluria. * Be aware of potential cross-reactivity with other sulfa-containing drugs. --- ***Disclaimer:*** *This information is intended for clinical use and does not substitute for professional medical advice. Always consult the most current prescribing information, institutional guidelines, and evidence-based resources for complete and up-to-date information.*