Septran%252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252520%252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252528co-Trimoxazole%252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252529

# Septran (Co-trimoxazole) ## Overview Septran is a combination of trimethoprim and sulfamethoxazole, a sulfonamide antibiotic. ## Primary Indications * **Urinary Tract Infections (UTIs):** Acute uncomplicated cystitis, prophylaxis against recurrent UTIs. * **Pneumocystis jirovecii Pneumonia (PCP):** Treatment and prophylaxis in immunocompromised patients. * **Bacterial Infections:** Treatment of infections caused by susceptible organisms, including *Haemophilus influenzae*, *Shigella*, *Streptococcus pneumoniae*, and *Staphylococcus aureus*. ## Adult Dosing * **UTIs:** 160 mg trimethoprim/800 mg sulfamethoxazole (1 double-strength tablet) every 12 hours for 3-7 days for acute cystitis. For prophylaxis, 1 double-strength tablet daily or 3 times weekly. * **PCP Treatment:** 15-20 mg/kg/day trimethoprim component, divided into 4 doses, given every 6 hours for 14-21 days. * **PCP Prophylaxis:** 1 double-strength tablet daily. * **Other Infections:** Standard dose is 1 double-strength tablet every 12 hours. Higher doses may be required for severe infections (e.g., 2 double-strength tablets every 12 hours). Maximum dose: 8 double-strength tablets (1600 mg trimethoprim/3200 mg sulfamethoxazole) per day. ## Pediatric Dosing Dosing is typically based on the trimethoprim component. * **UTIs:** 8 mg/kg/day trimethoprim component, divided into 2 doses, given every 12 hours. Duration varies by indication. * **PCP Treatment:** 15-20 mg/kg/day trimethoprim component, divided into 4 doses, given every 6 hours for 14-21 days. * **PCP Prophylaxis:** 5 mg/kg/day trimethoprim component, divided into 2 doses, given every 12 hours, for 3 consecutive days per week. * **Other Infections:** 10-15 mg/kg/day trimethoprim component, divided into 4 doses, given every 6 hours. ## Dose Adjustments * **Renal Impairment (CrCl < 15 mL/min):** Contraindicated. * **Renal Impairment (CrCl 15-30 mL/min):** Reduce dose by 25-50%. * **Renal Impairment (CrCl 30-60 mL/min):** Monitor serum levels. ## Contraindications * Documented hypersensitivity to trimethoprim, sulfamethoxazole, or sulfonamides. * Severe renal insufficiency (CrCl < 15 mL/min). * Megaloblastic anemia due to folate deficiency. * Infants less than 2 months of age (risk of kernicterus). * Patients with a history of drug-induced thrombocytopenia with either component. * Porphyria. ## Adverse Effects * **Common:** Nausea, vomiting, rash (can be severe, including Stevens-Johnson syndrome and toxic epidermal necrolysis), hyperkalemia. * **Less Common:** Diarrhea, headache, dizziness, pruritus, photosensitivity, leukopenia, thrombocytopenia, eosinophilia, elevated liver enzymes. * **Rare:** Anaphylaxis, crystalluria, aseptic meningitis, renal failure, hepatic necrosis, aplastic anemia, agranulocytosis. ## Key Drug Interactions * **ACE Inhibitors/ARBs/Potassium-Sparing Diuretics:** Increased risk of hyperkalemia. * **Warfarin:** Increased INR. Monitor INR closely and adjust warfarin dose. * **Methotrexate:** Increased methotrexate levels and potential for toxicity. May require increased folate supplementation. * **Digoxin:** Increased digoxin levels. Monitor digoxin levels. * **Cyclosporine:** Increased risk of nephrotoxicity. * **Oral Hypoglycemics:** Increased risk of hypoglycemia. * **Potassium Supplements:** Increased risk of hyperkalemia. * **Ticlopidine/Procainamide:** Increased risk of bone marrow suppression. ## Monitoring * Renal function (serum creatinine, CrCl). * Complete blood counts (CBC) with differential and platelet count, especially with prolonged use or in patients with G6PD deficiency. * Electrolytes, particularly potassium. * Liver function tests. * Signs of hypersensitivity reactions. ## Clinical Pearls * Encourage adequate fluid intake to prevent crystalluria. * Advise patients to report any skin rash, fever, sore throat, or signs of bleeding immediately. * Sulfonamides can displace bilirubin from albumin; avoid in late pregnancy and in neonates. * Co-trimoxazole can interfere with certain laboratory tests (e.g., creatinine assays, leading to falsely elevated results). * Folate supplementation may be considered, particularly in patients with megaloblastic anemia or those on long-term therapy. *** *Please verify current prescribing information for complete details.*