Septran%2525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252520%2525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252528co-Trimoxazole%2525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252529

# Septran (Co-Trimoxazole) ## Overview Septran is a combination antibiotic containing sulfamethoxazole and trimethoprim. It works by inhibiting bacterial folic acid synthesis. ## Primary Indications * Urinary tract infections (UTIs) * Pneumocystis jirovecii pneumonia (PJP) prophylaxis and treatment * Acute otitis media * Traveler's diarrhea * Shigellosis ## Adult Dosing * **Uncomplicated UTIs:** 1 double-strength (DS) tablet (160 mg trimethoprim/800 mg sulfamethoxazole) twice daily for 3 days. * **PJP Treatment:** 15-20 mg/kg/day of trimethoprim component, divided into 3-4 doses, given IV or PO for 14-21 days. * **PJP Prophylaxis:** 1 DS tablet once daily, or 1 DS tablet 3 times weekly (depending on protocol). * **Traveler's Diarrhea:** 1 DS tablet twice daily for 5 days. * Maximum dose: Generally, no more than 8 DS tablets (640 mg trimethoprim/3200 mg sulfamethoxazole) per day should be administered. ## Pediatric Dosing Dosing is based on the trimethoprim component and is generally 8-10 mg/kg/day divided every 12 hours for UTIs. For PJP, dosing is 15-20 mg/kg/day divided every 6 hours. Specific weight-based dosing for various indications should be followed per institutional guidelines or product labeling. * **PJP Prophylaxis:** 150 mg/m²/day of trimethoprim component, given PO in 2 divided doses. ## Dose Adjustments * **Renal Impairment:** Dose adjustment is required based on creatinine clearance (CrCl). * CrCl > 30 mL/min: No adjustment needed. * CrCl 15-30 mL/min: Half the usual dose. * CrCl < 15 mL/min: Avoid use. * **Hepatic Impairment:** Use with caution. ## Contraindications * Known hypersensitivity to trimethoprim or sulfonamides. * History of drug-induced immune thrombocytopenia with use of trimethoprim or sulfonamides. * Marked liver atrophy, jaundice, or severe parenchymal liver disease. * Infants less than 2 months of age (risk of kernicterus). * Anuria or severe renal insufficiency when plasma levels cannot be monitored. ## Adverse Effects Common: Nausea, vomiting, rash, pruritus, hyperkalemia. Serious: Stevens-Johnson syndrome, toxic epidermal necrolysis, aplastic anemia, agranulocytosis, severe hepatic reactions, hyperkalemia, crystalluria (ensure adequate hydration). ## Key Drug Interactions * **Warfarin:** Increased INR. Monitor INR closely. * **Methotrexate:** Increased methotrexate levels. Monitor for methotrexate toxicity. * **Potassium-sparing diuretics:** Increased risk of hyperkalemia. * **ACE inhibitors/ARBs:** Increased risk of hyperkalemia. * **Digoxin:** May increase digoxin levels. Monitor digoxin levels. * **Cyclosporine:** Increased cyclosporine levels. ## Monitoring * Renal function (BUN, creatinine). * Electrolytes, especially potassium. * Complete blood count (CBC) with differential, particularly during prolonged therapy or in immunocompromised patients. * Liver function tests. * Signs and symptoms of hypersensitivity reactions. * Adequate fluid intake to prevent crystalluria. ## Clinical Pearls * Administer oral doses with food or fluids to minimize gastrointestinal upset. * Ensure adequate hydration during treatment to prevent crystalluria. * Co-trimoxazole is associated with a higher risk of hypersensitivity reactions in patients with HIV/AIDS, though desensitization protocols may be considered. * Discontinue if a rash develops. Please verify current prescribing information for specific patient populations and indications.