Please check your internet connection and try again.
## Septran (Trimethoprim/Sulfamethoxazole)
### Overview
Septran is a combination antibiotic of trimethoprim and sulfamethoxazole, often in a 1:5 ratio. It is a synthetic broad-spectrum bacteriostatic agent that works by inhibiting sequential steps in the folic acid synthesis pathway.
### Primary Indications
* **Urinary Tract Infections (UTIs):** Uncomplicated UTIs.
* **Pneumocystis jirovecii Pneumonia (PJP):** Treatment and prophylaxis.
* **Bacterial Infections:** Certain respiratory, GI, and skin infections caused by susceptible organisms.
### Adult Dosing
* **Uncomplicated UTIs:** 1 DS (double strength) tablet every 12 hours for 3-7 days.
* **PJP Treatment:** 15 mg/kg/day of trimethoprim component, divided into 4 doses (e.g., 20 mg/kg/day total for TMP/SMX), given IV or orally for 14-21 days.
* **PJP Prophylaxis:** 1 DS tablet once daily, or 1 DS tablet 3 times a week on alternate days.
* **Other Infections:** Typical dose is 1 DS tablet every 12 hours. Higher doses may be used for severe infections. Maximum daily dose is typically 6 DS tablets.
### Pediatric Dosing
* Dosing is based on the trimethoprim component.
* **UTIs and most other infections:** 8 mg/kg/day of trimethoprim, divided into 2 doses (e.g., 40 mg/kg/day total for TMP/SMX), given every 12 hours.
* **PJP Treatment:** 15 mg/kg/day of trimethoprim, divided into 4 doses (e.g., 20 mg/kg/day total for TMP/SMX), given every 6 hours.
* **PJP Prophylaxis:** 5 mg/kg/day of trimethoprim, divided into 2 doses (e.g., 10 mg/kg/day total for TMP/SMX), given every 12 hours.
* **Note:** For children < 2 months of age, use is generally not recommended due to risk of kernicterus.
### Dose Adjustments
* **Renal Impairment:**
* CrCl > 30 mL/min: No adjustment needed.
* CrCl 15-30 mL/min: Half the usual maintenance dose.
* CrCl < 15 mL/min: Avoid use or administer with extreme caution and consider alternate therapy.
### Contraindications
* Known hypersensitivity to trimethoprim or sulfonamides.
* Documented megaloblastic anemia due to folate deficiency.
* Infants less than 2 months of age (except for specific indications like PJP prophylaxis).
* Late pregnancy.
### Adverse Effects
* **Common:** Nausea, vomiting, rash, urticaria.
* **Serious:** Severe skin reactions (Stevens-Johnson syndrome, toxic epidermal necrolysis), blood dyscrasias (anemia, leukopenia, thrombocytopenia), hyperkalemia, renal impairment, hepatotoxicity, photosensitivity, interstitial nephritis.
### Key Drug Interactions
* **Warfarin:** Increased INR. Monitor INR closely and adjust warfarin dose as needed.
* **ACE Inhibitors/ARBs/Potassium-Sparing Diuretics:** Increased risk of hyperkalemia.
* **Methotrexate:** Increased methotrexate levels and toxicity.
* **Potassium Supplements:** Increased risk of hyperkalemia.
* **Thiazide Diuretics:** Increased risk of thrombocytopenia in elderly patients.
* **CYP2C9 Substrates:** Potentially increased levels of substrates metabolized by CYP2C9.
### Monitoring
* **Renal function:** Especially in patients with pre-existing renal disease or elderly patients.
* **Complete blood count (CBC):** Baseline and periodically, especially with prolonged therapy or in immunocompromised patients. Monitor for signs of blood dyscrasias.
* **Electrolytes:** Particularly potassium.
* **Skin:** Monitor for rash or signs of hypersensitivity.
* **Therapeutic drug monitoring:** May be considered for PJP treatment, especially in patients with impaired renal function.
### Clinical Pearls
* Encourage increased fluid intake to prevent crystalluria.
* Advise patients to report any rash, sore throat, fever, or unusual bleeding/bruising immediately.
* Photosensitivity is common; advise sun protection.
* Sulfonamides can displace bilirubin from albumin; avoid in late pregnancy and in neonates.
***
*Disclaimer: This information is intended for healthcare professionals and does not replace comprehensive prescribing information. Always consult the current official prescribing information and relevant guidelines before making clinical decisions.*
