Please check your internet connection and try again.
# Septra (Co-trimoxazole)
## Overview
Septra is a combination antibiotic containing trimethoprim and sulfamethoxazole. It is a broad-spectrum antimicrobial effective against many Gram-positive and Gram-negative bacteria.
## Primary Indications
* Urinary tract infections (UTIs)
* Pneumocystis jirovecii pneumonia (PCP) prophylaxis and treatment
* Shigellosis
* Otitis media
* Traveler's diarrhea
* *Haemophilus influenzae* infections
## Adult Dosing
**Uncomplicated Urinary Tract Infections:**
* 1 double-strength (DS) tablet (160 mg trimethoprim/800 mg sulfamethoxazole) orally every 12 hours for 3 days.
**Complicated Urinary Tract Infections and Prostatitis:**
* 1 DS tablet (160 mg trimethoprim/800 mg sulfamethoxazole) orally every 12 hours. Duration varies by indication (e.g., 10-14 days for complicated UTIs, 4-6 weeks for prostatitis).
**Pneumocystis jirovecii Pneumonia (Treatment):**
* 15-20 mg/kg/day of trimethoprim component and 75-100 mg/kg/day of sulfamethoxazole component, divided into 4 doses, orally or IV for 14-21 days. Maximum daily dose: 1200 mg trimethoprim and 6000 mg sulfamethoxazole.
**Pneumocystis jirovecii Pneumonia (Prophylaxis):**
* 1 DS tablet (160 mg trimethoprim/800 mg sulfamethoxazole) orally once daily.
* Alternatively, 1 DS tablet orally 3 times a week.
**Shigellosis:**
* 1 DS tablet (160 mg trimethoprim/800 mg sulfamethoxazole) orally every 12 hours for 5 days.
**Traveler's Diarrhea:**
* 1 DS tablet (160 mg trimethoprim/800 mg sulfamethoxazole) orally every 12 hours for up to 3 days.
## Pediatric Dosing
Dosing is typically based on the trimethoprim component. Pediatric dosing requires careful calculation and is often guided by specific institutional protocols or clinical guidelines.
**General Pediatric Dosing (e.g., UTIs, otitis media):**
* Trimethoprim 8 mg/kg/day and sulfamethoxazole 40 mg/kg/day, divided into 2 or 4 doses.
* Oral dose: e.g., 10 mg/kg/day of trimethoprim and 50 mg/kg/day of sulfamethoxazole, divided every 12 hours.
* Maximum daily dose should not exceed adult doses.
**Pneumocystis jirovecii Pneumonia (Treatment):**
* 15-20 mg/kg/day of trimethoprim component and 75-100 mg/kg/day of sulfamethoxazole component, divided into 4 doses, orally or IV for 14-21 days.
**Pneumocystis jirovecii Pneumonia (Prophylaxis):**
* 150 mg/m² of trimethoprim and 750 mg/m² of sulfamethoxazole per week, divided into 2 or 3 doses.
## Dose Adjustments
**Renal Impairment:**
* Creatinine clearance (CrCl) > 30 mL/min: No adjustment needed.
* CrCl 15-30 mL/min: Reduce dose by 25-50%.
* CrCl < 15 mL/min: Avoid use or reduce dose significantly (e.g., 75% reduction).
**Hepatic Impairment:**
* Use with caution. Dose adjustment may be necessary; consult with a specialist.
## Contraindications
* Hypersensitivity to trimethoprim or sulfonamides.
* Documented megaloblastic anemia due to folate deficiency.
* Infants less than 2 months of age (risk of kernicterus).
* Severe renal or hepatic insufficiency when achievable concentrations cannot be measured or monitored.
* Patients with a history of drug-induced thrombocytopenia with either component.
## Adverse Effects
* **Common:** Rash, nausea, vomiting, diarrhea.
* **Serious:**
* Hypersensitivity reactions (including Stevens-Johnson syndrome, toxic epidermal necrolysis).
* Hematologic abnormalities (anemia, leukopenia, thrombocytopenia, aplastic anemia).
* Hyperkalemia.
* Hepatitis, cholestatic jaundice.
* Renal impairment (crystalluria).
* Photosensitivity.
* *Clostridioides difficile*-associated diarrhea.
## Key Drug Interactions
* **Warfarin:** Increased INR. Monitor INR closely and adjust warfarin dose.
* **ACE inhibitors/ARBs/Potassium-sparing diuretics:** Increased risk of hyperkalemia.
* **Methotrexate:** Increased methotrexate levels and toxicity. Monitor for signs of toxicity; consider concomitant folate supplementation if indicated.
* **Potassium:** May increase serum potassium.
* **Cyclosporine:** May increase cyclosporine levels.
* **Oral hypoglycemics:** Increased risk of hypoglycemia.
* **Digoxin:** May increase digoxin levels.
## Monitoring
* Renal function (BUN, creatinine).
* Complete blood counts (CBC) with differential, especially with prolonged therapy or in immunocompromised patients.
* Serum electrolytes, particularly potassium.
* Liver function tests.
* Signs of hypersensitivity reactions and other adverse effects.
## Clinical Pearls
* Co-trimoxazole can inhibit cytochrome P450 enzymes, potentially affecting other drug metabolism.
* Adequate fluid intake is essential to prevent crystalluria.
* Monitor for signs of folate deficiency, especially in elderly patients, those with poor nutritional status, or on long-term therapy. Consider folate supplementation.
* Dose adjustments are crucial in patients with renal impairment.
***
*This information is intended for clinical use and does not replace professional medical advice. Always consult the current prescribing information and relevant guidelines for complete details.*
