Septran%252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252520%252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252528co-Trimoxazole%252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252529

## Overview Septran is a brand name for co-trimoxazole, a combination antibiotic of trimethoprim and sulfamethoxazole. ## Primary Indications * Urinary tract infections (UTIs) * Pneumocystis jirovecii pneumonia (PCP) prophylaxis and treatment * Acute exacerbations of chronic bronchitis * Shigellosis * Traveler's diarrhea (enterotoxigenic E. coli) * *Stenotrophomonas maltophilia* infections ## Adult Dosing * **UTIs:** 1 double-strength (DS) tablet (160 mg trimethoprim/800 mg sulfamethoxazole) every 12 hours for 3-7 days. * **PCP Treatment:** 2 DS tablets (160 mg trimethoprim/800 mg sulfamethoxazole) every 6 hours for 14-21 days. * **PCP Prophylaxis:** 1 DS tablet (160 mg trimethoprim/800 mg sulfamethoxazole) daily, or 1 DS tablet three times weekly on alternate days. * **Other Infections:** Dosing varies based on severity and site of infection. Typically, 1 DS tablet every 12 hours. Higher doses may be used for severe infections (e.g., 2 DS tablets every 12 hours). ## Pediatric Dosing Dosing is based on trimethoprim component, typically 8-10 mg/kg/day divided into two doses. Sulfamethoxazole dose is generally a 5:1 ratio with trimethoprim. * **UTIs:** 8 mg/kg/day of trimethoprim and 40 mg/kg/day of sulfamethoxazole, given in two divided doses every 12 hours for 7-14 days. * **PCP Treatment:** 20 mg/kg/day of trimethoprim and 100 mg/kg/day of sulfamethoxazole, divided into four doses every 6 hours for 14-21 days. * **PCP Prophylaxis:** 5 mg/kg/day of trimethoprim and 25 mg/kg/day of sulfamethoxazole, given in two divided doses daily. * **Note:** Specific pediatric dosing often requires calculation and may depend on local guidelines or prescriber preference. ## Dose Adjustments * **Renal Impairment:** Dose adjustment is necessary. * Creatinine clearance (CrCl) > 30 mL/min: Full dose. * CrCl 15-30 mL/min: Half the usual dose. * CrCl < 15 mL/min: Avoid use or administer 1/4 the usual dose every 24 hours. ## Contraindications * Known hypersensitivity to trimethoprim or sulfonamides. * Documented megaloblastic anemia due to folate deficiency. * Infants less than 2 months of age (due to risk of kernicterus). * Severe renal insufficiency or hepatic insufficiency when functional tests cannot be monitored. * History of drug-induced thrombocytopenia with either component. ## Adverse Effects * **Common:** Nausea, vomiting, rash (including Stevens-Johnson syndrome and toxic epidermal necrolysis, which are rare but serious), hyperkalemia, elevated liver enzymes. * **Less Common:** Diarrhea, headache, dizziness, photosensitivity, leukopenia, thrombocytopenia, eosinophilia, neutropenia. * **Rare but Serious:** Agranulocytosis, aplastic anemia, crystalluria, hepatic necrosis, peripheral neuritis. ## Key Drug Interactions * **Warfarin:** Increased INR. Monitor INR closely. * **Potassium-sparing diuretics (e.g., spironolactone, amiloride):** Increased risk of hyperkalemia. * **ACE inhibitors/ARBs:** Increased risk of hyperkalemia. * **Methotrexate:** Increased methotrexate levels and potential toxicity. * **Sulfonylureas (e.g., glipizide, glyburide):** Increased risk of hypoglycemia. * **Rifampin:** May increase or decrease co-trimoxazole levels. * **Digoxin:** May increase digoxin levels. ## Monitoring * Renal function (BUN, creatinine). * Electrolytes (especially potassium). * Complete blood counts (CBC) with differential, particularly with prolonged therapy or in immunocompromised patients. * Liver function tests. * Signs of hypersensitivity reactions. * INR if co-administered with warfarin. ## Clinical Pearls * Encourage adequate fluid intake to prevent crystalluria. * Advise patients to report any rash, fever, sore throat, or signs of bleeding immediately. * Photosensitivity can occur; recommend sun protection. * Co-trimoxazole is generally avoided in the third trimester of pregnancy due to potential for sulfonamide transfer to the fetus, which can interfere with bilirubin metabolism. *** *Disclaimer: This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and relevant guidelines for complete and up-to-date details.*