Trimethoprim-Sulfamethoxazole

C. diff Risk

Low

Oral Bioavailability

Excellent

Approximate Cost

Dosing

PO: 1-2 DS tabs PO BID

IV: 10-20 mg TMP/kg/day IV divided in 3-4 doses

General Information

Common Usage

  •  Urinary tract infections

  •  Susceptible MRSA infections

  •  Stenotrophomonas infections

  •  Pneumocystis jirovecii pneumonia (Treatment or prophylaxis)

Drug Monitoring

Lab

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

Clinical

  • Hypersensitivty/rash

  • GI effects

  • Increased INR on warfarin

Adverse Effects

  •  Gastrointestinal upset common

  •  Bone marrow suppression

  •  Hyperkalemia

  •  Renal failure

  •  Hepatitis

  •  Aseptic meningitis

  •  Stevens Johnson syndrome/toxic epidermal necrolysis

  •  Other rashes

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