Please check your internet connection and try again.
# Septran (co-trimoxazole)
## Overview
Co-trimoxazole is a combination antibiotic of trimethoprim and sulfamethoxazole, which work synergistically to inhibit bacterial folic acid synthesis.
## Primary Indications
* Urinary tract infections (UTIs)
* Pneumocystis jirovecii pneumonia (PJP) prophylaxis and treatment
* Acute otitis media
* Acute exacerbations of chronic bronchitis
* Shigellosis
* Gastroenteritis due to susceptible organisms
## Adult Dosing
Dosing is typically expressed as the amount of trimethoprim/sulfamethoxazole (TMP/SMX). The standard strength tablet contains 80 mg TMP and 400 mg SMX.
* **UTIs and acute exacerbations of chronic bronchitis:** 1 double-strength (DS) tablet (160 mg TMP/800 mg SMX) orally every 12 hours for 3-7 days for UTIs and 7-14 days for chronic bronchitis.
* **PJP Treatment:** 15-20 mg TMP/kg/day divided into 3-4 doses orally or IV, given over 14-21 days.
* **PJP Prophylaxis:** 1 DS tablet (160 mg TMP/800 mg SMX) orally once daily, or 1 DS tablet three times weekly.
* **Shigellosis:** 1 DS tablet (160 mg TMP/800 mg SMX) orally every 12 hours for 5-7 days.
Maximum dose: Typically 2 DS tablets every 12 hours.
## Pediatric Dosing
Dosing is based on trimethoprim component.
* **UTIs and acute otitis media:** 8-10 mg TMP/kg/day divided into two doses, orally every 12 hours.
* **PJP Prophylaxis:** 5 mg TMP/kg/day divided into two doses, orally every 12 hours, for 3 consecutive days per week.
* **PJP Treatment:** 15-20 mg TMP/kg/day divided into 3-4 doses, orally or IV, every 6-8 hours for 14-21 days.
Maximum pediatric dose: Generally equivalent to adult DS tablet every 12 hours.
## Dose Adjustments
* **Renal Impairment:**
* CrCl >30 mL/min: Standard dose.
* CrCl 15-30 mL/min: Reduce dose by 50%.
* CrCl <15 mL/min: Avoid use or administer 50% of the usual dose every other day.
* **Hepatic Impairment:** Use with caution; dose adjustments may be needed.
## Contraindications
* Known hypersensitivity to trimethoprim, sulfamethoxazole, or sulfonamides.
* Documented megaloblastic anemia due to folate deficiency.
* Infants less than 2 months of age (increased risk of kernicterus).
* Severe renal or hepatic insufficiency where drug levels cannot be monitored.
* History of drug-induced thrombocytopenia with platelet counts below 150,000/mm³.
## Adverse Effects
* **Common:** Rash, nausea, vomiting, diarrhea.
* **Serious:** Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), hypersensitivity reactions, hematologic toxicity (anemia, leukopenia, thrombocytopenia, agranulocytosis), hyperkalemia, renal impairment, liver injury, photosensitivity.
## Key Drug Interactions
* **Warfarin:** Increased INR; monitor INR closely.
* **ACE inhibitors/ARBs, potassium-sparing diuretics, potassium supplements:** Increased risk of hyperkalemia.
* **Methotrexate:** Increased risk of bone marrow suppression.
* **Cyclosporine:** Increased cyclosporine levels and nephrotoxicity.
* **Potassium-sparing diuretics:** Increased risk of hyperkalemia.
* **Sulfonylureas:** Increased hypoglycemic effect.
* **Dofetilide:** Contraindicated due to increased risk of ventricular arrhythmias.
## Monitoring
* Complete blood counts (CBC) with differential and platelet counts, especially with prolonged therapy or in patients with G6PD deficiency.
* Renal function (BUN, creatinine).
* Liver function tests (LFTs).
* Electrolytes, particularly potassium.
* Therapeutic drug levels may be considered in specific situations (e.g., severe infections, renal impairment).
## Clinical Pearls
* Hydration is important to prevent crystalluria.
* Advise patients to report any rash, sore throat, fever, or unusual bleeding/bruising immediately.
* Discontinue if rash appears.
* Use with caution in patients with G6PD deficiency, severe allergies, or asthma.
* Consider folate supplementation in patients receiving long-term co-trimoxazole therapy, particularly those with conditions predisposing to folate deficiency.
***
**Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines for complete and up-to-date details.
