Antimicrobials
Co-trimoxazole (Sulfamethoxazole/Trimethoprim)

Co-trimoxazole (Sulfamethoxazole/Trimethoprim)

Low
Excellent
IV$100/d PO$1/d

General Information

  •  Urinary tract infections
  •  Susceptible MRSA infections
  •  Stenotrophomonas infections
  •  Pneumocystis jirovecii pneumonia (treatment or prophylaxis)
  •  Creatinine and electrolytes in patients at increased risk renal failure
  •  Potassium
  •  CBC
  •  Stevens Johnson syndrome/toxic epidermal necrolysis & other rashes
  •  Gastrointestinal upset (common)
  •  Bone marrow suppression
  •  Hyperkalemia
  •  Renal failure
  •  Hepatitis
  •  Aseptic meningitis
  •  Methotrexate- marrow suppression
  •  Increases phenytoin
  •  Increases INR with warfarin

Concentration: (Per 1 mL) Trimethoprim 8 mg and Sulfamethoxazole 40 mg (Only available via Special Access Program with Health Canada)

Taste: Very palatable

Not all strengths of oral liquids are listed nor are available on IWK formulary

Pediatric Tablet: Trimethoprim 20 mg and Sulfamethoxazole 100 mg

Adult Tablet: Trimethoprim 80 mg and Sulfamethoxazole 400 mg

Double Strength Tablet: Trimethoprim 160 mg and Sulfamethoxazole 800 mg

Tablets and capsules are preferred especially over an unpleasant tasting liquid. Not all strengths of oral tablets/capsules are listed and they are not all available on the IWK formulary.

Dosing is based on the trimethoprim (TMP) component

Pediatric strength tablets:100mg SMX/ 20 mg TMP

Regular strength tablets: 400mg SMX/ 80 mg TMP

Double strength tablets: 800 mg SMX/ 160 mg TMP

Suspension: (per 1 mL): 40 mg SMX/8 mg TMP

Injection: (per 1 mL): 80 mg SMX/16 mg TMP

Antimicrobial class: Sulfonamide - Antifolate

Average serum half life: TMP (prolonged in renal failure)

  • Newborns: ~19 hours; range: 11-27 hours
  •  Infants 2 months to 1 year: ~4.6 hours; range: 3-6 hours
  •  Children 1-10 years: 3.7-5.5 hours
  •  Children and Adolescents >10 years: 8.19 hours
  •  Adults: 6-11 hours

SMX: 9-12 hours, prolonged in renal failure (Adult data)

Route of Elimination: Both excreted in urine as metabolites and unchanged drug