Trimethoprim-Sulfamethoxazole

C. diff Risk

Low

Oral Bioavailability

Excellent

Dosing

PO: 1-2 DS tabs PO BID

IV: 15-20mg/kg/day of TMP IV in 4 divided doses

eGFR 0 - 10eGFR 10 - 30eGFR > 30Not recommended.

If necessary 5mg/kg/day.50% of usual dosingUsual dosing

5-10mg/kg of TMP IV q24h

2.5-10mg/kg of TMP IV q12h depending on indication

General Information

Adverse Effects

  • Gastrointestinal upset common

  • Bone marrow suppression

  • Hyperkalemia

  • Renal failure

  • Hepatitis

  • Aseptic meningitis

  • Stevens Johnson syndrome/toxic epidermal necrolysis

  • Other rashes

Common Usage

  • Urinary tract infections

  • Susceptible MRSA infections

  • Stenotrophomonas infections

  • Pneumocystis jirovecii pneumonia (Treatment or prophylaxis)

Drug Monitoring

Follow creatinine and electrolytes in patients at increased risk renal failure, hyperkalemia.

Major Interactions

  • ACEi - Increased serum potassium level

  • Increases amantadine levels

  • Decreases cyclosporine

  • Methotrexate - Marrow suppression

  • Increases phenytoin

  • Increases rifampin

  • Increases INR with warfarin

Pharmacology

Antimicrobial class: Sulfonamide - Antifolate

Pregnancy category: C

Average serum half life: 10 hours

Biliary penetration: Moderate

CSF penetration: Therapeutic

Lung penetration: Therapeutic

Urine penetration: Therapeutic