Septran%25252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252520%25252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252528co-Trimoxazole%25252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252529

# Septran (Co-trimoxazole) ## Overview Septran is a combination antibiotic containing trimethoprim and sulfamethoxazole. ## Primary Indications * Treatment of various bacterial infections including: * Urinary tract infections (UTIs) * Pneumocystis jirovecii pneumonia (PJP) prophylaxis and treatment * Bacterial prostatitis * Acute exacerbations of chronic bronchitis * Shigellosis gastroenteritis * *Staphylococcus aureus* infections (including MRSA, depending on local susceptibility) ## Adult Dosing Dosing is typically based on the trimethoprim component. The standard adult dose is 160 mg trimethoprim / 800 mg sulfamethoxazole (one double-strength tablet) every 12 hours. * **UTIs, acute exacerbations of chronic bronchitis:** 160 mg trimethoprim / 800 mg sulfamethoxazole every 12 hours for 7-14 days. * **PJP Treatment:** 15-20 mg/kg/day trimethoprim divided into 3-4 doses (given orally or IV) for 14-21 days. * **PJP Prophylaxis:** 160 mg trimethoprim / 800 mg sulfamethoxazole daily OR 80 mg trimethoprim / 400 mg sulfamethoxazole twice daily, 3 times a week on alternate days. * **Shigellosis:** 160 mg trimethoprim / 800 mg sulfamethoxazole every 12 hours for 5 days. ## Pediatric Dosing Dosing is based on trimethoprim mg/kg/day. The usual ratio is 5:1 trimethoprim to sulfamethoxazole. * **General Infections:** 8-10 mg/kg/day of trimethoprim, divided into two doses every 12 hours. * **PJP Treatment:** 15-20 mg/kg/day of trimethoprim, divided into three or four doses every 6-8 hours for 14-21 days. * **PJP Prophylaxis:** 10 mg/kg/day of trimethoprim, divided into two doses every 12 hours, given 3 times a week on alternate days OR 5 mg/kg/dose of trimethoprim twice daily, 3 times a week on alternate days. *Maximum daily dose for children should not exceed the adult dose of 320 mg trimethoprim per day.* ## Dose Adjustments * **Renal Impairment:** * CrCl > 30 mL/min: Full dose. * CrCl 15-30 mL/min: Half the usual dose. * CrCl < 15 mL/min: Avoid use or administer one-third the usual dose every 12 hours. ## Contraindications * Known hypersensitivity to trimethoprim, sulfamethoxazole, or sulfonamides. * History of drug-induced thrombocytopenia with either agent. * Documented megaloblastic anemia due to folate deficiency. * Infants younger than 2 months (risk of kernicterus). * Severe renal insufficiency where drug levels cannot be monitored. * Severe hepatic insufficiency. ## Adverse Effects * **Common:** Nausea, vomiting, rash (can be severe and life-threatening, including Stevens-Johnson syndrome and toxic epidermal necrolysis), hyperkalemia, eosinophilia. * **Serious:** Hematologic abnormalities (anemia, leukopenia, thrombocytopenia, aplastic anemia), hepatotoxicity, renal dysfunction, photosensitivity, aseptic meningitis, hyperkalemia. ## Key Drug Interactions * **Warfarin:** Increased INR. Monitor INR closely. * **ACE Inhibitors / ARBs / Potassium-Sparing Diuretics:** Increased risk of hyperkalemia. * **Methotrexate:** Increased methotrexate toxicity (may inhibit DHFR enzyme). * **Digoxin:** Increased digoxin levels. * **Potassium Supplements:** Increased risk of hyperkalemia. * **Cyclosporine:** Increased cyclosporine levels, potentially nephrotoxic. * **Thiazide Diuretics:** Increased risk of thrombocytopenia, especially in elderly. ## Monitoring * Renal function (BUN, creatinine). * Electrolytes (especially potassium). * Complete blood count (CBC) with differential and platelet count, particularly with prolonged therapy or in immunocompromised patients. * Liver function tests (LFTs). * Signs and symptoms of hypersensitivity reactions. ## Clinical Pearls * Encourage adequate fluid intake to prevent crystalluria. * Advise patients to report any new rash, fever, sore throat, mouth sores, or unusual bleeding/bruising immediately. * Avoid concurrent use with folic acid supplements unless specifically indicated for folate deficiency, as it can interfere with efficacy. * Sulfonamides can displace bilirubin from albumin in neonates, increasing the risk of kernicterus. --- ***Disclaimer:** This information is intended for educational purposes and does not substitute for professional medical advice. Always consult the most current prescribing information and your healthcare provider for any medical decisions.*