Trimethoprim-sulfamethoxazole

C. diff Risk

Low

Oral Bioavailability

Excellent

Approximate Cost

IV$100/d PO$1/d

Dosing

PO: 1-2 DS tabs PO BID
IV: 15-20mg/kg/day of TMP IV in 4 divided doses

General Information

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

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

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