Trimethoprim-sulfamethoxazole

C. diff Risk

Low

Oral Bioavailability

Excellent

Approximate Cost

Dosing

Routine Indications: 1-2 DS tabs PO BID (Note: DS = 160mg trimethoprim) High Dose Therapy: 15-20mg/kg/day of trimethoprim IV in 3-4 divided doses

General Information

Common Usage

Urinary tract infections, skin and soft tissue infections, pulmonary infections, bone and joint infections, meningitis
Susceptible MRSA infections, Stenotrophomonas infections, Pneumocystis jirovecii pneumonia (treatment or prophylaxis), Nocardia infections

Drug Monitoring

Follow creatinine, potassium, BUN in patients at increased risk renal failure or hyperkalemia

CBC

Adverse Effects

Stevens Johnson syndrome/toxic epidermal necrolysis, other rashes, gastrointestinal upset common, bone marrow suppression, hyperkalemia, renal failure, hepatitis, aseptic meningitis

Major Interactions

  • ACEi - increased serum potassium level

  • Increases amantadine levels

  • ¬†Decreases cyclosporine

  • Methotrexate- marrow suppression

  • ¬†Increases phenytoin

  • Increases rifampin

  • ¬†Increases INR with warfarin

Additional Information

High dose therapy required for treatment of Pneumocystis pneumonia and Stenotrophomonas maltophilia infections

Pharmacology

Antimicrobial class: Sulfonamide - Antifolate

Pregnancy category: C

Average serum half life: 10.0

Biliary penetration: Moderate

CSF penetration: Therapeutic

Lung penetration: Therapeutic

Urine penetration: Therapeutic