C. diff Risk


Oral Bioavailability

Good (70 to 90%)

Approximate Cost

$0.08 (PO)
$85.80 (IV)

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

  •  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

Tablet/Capsule Strengths

No prescribing restrictions

Additional Information

IV Administration
Dilute each 5mL amp in 100-125 mL NS or D5W. Administer dose over 60-90 min.

May dilute each 5 mL amp in 50-75 mL if fluid restricted but stability may be markedly decreased

Each 5 mL ampoule contains:

  • 80 mg Trimethoprim

  • 400 mg Sulfamethoxazole

Each single strength (SS) tablet contains:

  • 80 mg Trimethoprim

  • 400 mg Sulfamethoxazole

Each double strength (DS) tablet contains:

  • 160mg Trimethoprim

  • 800 mg Sulfamethoxazole

EH prescribing restrictions

Community IV Formulary (Metro Area)

Tablets may be crushed for NG administration; Liquid formulation is also available.

10mL Oral liquid = 1 single strength (SS) tablet

20mL Oral liquid = 1 double strength (DS) tablet


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