Please check your internet connection and try again.
# Septran (Co-trimoxazole)
## Overview
Co-trimoxazole is a combination antibiotic consisting of trimethoprim and sulfamethoxazole in a 1:5 ratio. It works by inhibiting sequential steps in the folic acid synthesis pathway, leading to bacterial cell death.
## Primary Indications
* **Urinary Tract Infections (UTIs):** Acute uncomplicated UTIs.
* **Pneumocystis jirovecii Pneumonia (PJP):** Treatment and prophylaxis.
* **Bacterial Infections:** Such as otitis media, shigellosis, and certain respiratory, gastrointestinal, and urinary tract infections caused by susceptible organisms.
## Adult Dosing
* **Acute 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 (based on trimethoprim component) divided into 3 or 4 doses, given orally or IV, for 14-21 days.
* **PJP Prophylaxis:** 1 DS tablet once daily, or 1 DS tablet 3 times weekly.
* **Other Infections:** Typical dose is 1 DS tablet every 12 hours. Severe infections may require up to 2 DS tablets every 12 hours. Duration varies by infection.
## Pediatric Dosing
Dosing is based on the trimethoprim component, typically 5-10 mg/kg/day for UTIs and otitis media, and 15-20 mg/kg/day for PJP treatment, divided into 2-4 doses. Oral suspension is often used. Specific age and weight-based dosing charts should be consulted.
* **PJP Prophylaxis (infants > 6 weeks):** 7 mg/kg/day of trimethoprim plus 35 mg/kg/day of sulfamethoxazole, divided into two doses, given on alternate days. Alternatively, 150 mg/m^2/day of trimethoprim plus 750 mg/m^2/day of sulfamethoxazole, divided into two doses, given on 3 consecutive days per week.
## Dose Adjustments
* **Renal Impairment:** Adjust dose based on creatinine clearance (CrCl).
* CrCl > 30 mL/min: No adjustment.
* CrCl 15-30 mL/min: Give usual dose every 12 hours.
* CrCl < 15 mL/min: Avoid use or give 50% of usual dose every 12 hours.
* **Hepatic Impairment:** Use with caution; dose adjustment may be needed.
## Contraindications
* Known hypersensitivity to trimethoprim, sulfonamides, or any component of the formulation.
* History of drug-induced immune thrombocytopenia with prior use of trimethoprim or sulfonamides.
* 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 adequate clinical monitoring is not feasible.
## Adverse Effects
* **Common:** Nausea, vomiting, rash, hyperkalemia.
* **Serious:** Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), exfoliative dermatitis, bone marrow suppression (anemia, leukopenia, thrombocytopenia), severe hypersensitivity reactions, hyperkalemia, hyponatremia, crystalluria, hepatic dysfunction, pseudomembranous colitis.
## Key Drug Interactions
* **Warfarin:** Increased INR. Monitor INR closely.
* **ACE Inhibitors/ARBs/Potassium-Sparing Diuretics:** Increased risk of hyperkalemia.
* **Methotrexate:** Increased risk of bone marrow suppression.
* **Diuretics (especially thiazides):** Increased risk of thrombocytopenia in elderly patients.
* **Cyclosporine:** May increase cyclosporine levels.
* **Potassium Supplements:** Increased risk of hyperkalemia.
## Monitoring
* **Renal Function:** Baseline and periodically, especially in elderly patients or those with renal impairment.
* **Complete Blood Counts (CBCs):** Baseline and periodically (e.g., every 2 weeks during long-term therapy), especially in patients with G6PD deficiency or folate deficiency. Discontinue if significant bone marrow suppression occurs.
* **Electrolytes:** Particularly potassium and sodium.
* **Liver Function Tests (LFTs):** Periodically, especially in patients with pre-existing liver disease.
* **Signs of Hypersensitivity:** Monitor for rash and other signs of allergic reaction.
* **Fluid Intake and Urine Output:** To prevent crystalluria.
## Clinical Pearls
* Co-trimoxazole is generally well-absorbed orally.
* Patients should be advised to drink plenty of fluids to prevent crystalluria.
* Rash is a common side effect and may herald more serious dermatologic reactions. Prompt discontinuation is advised if rash occurs.
* Caution in patients with G6PD deficiency, as hemolytic anemia can occur.
* Sulfonamides can displace bilirubin from albumin; avoid in neonates and near term in pregnancy.
* Dosing in obese patients may require adjustments based on lean body weight.
***
*Please verify the current prescribing information for complete details and any updates.*
