Sulfamethoxazole + Trimethoprim

C difficile risk
Oral Bioavailability


Dose listed as trimethoprim (TMP) component

IVPO- 8-20mg IV TMP/kg/day divided q6-12h

  • Pneumocystis jiroveci Treatment: 15-20 mg/kg/day IV divided q6-8h- sulfamethoxazole/trimethoprim 800/160 to 1600/320 mg PO q12h

  • Pneumocystis jiroveci Treatment: 15-20 mg/kg/day PO divided q6-8h

Dose listed as trimethoprim (TMP) componentUse of sulfamethoxazole + trimethoprim in moderate to severe renal dysfunction has not been adequately studied, close monitoring of patient response, electrolytes and serum creatinine recommended

CrCl 30-49CrCl 15-29CrCl <15Usual dose- 50% of usual dose IV/PO

  • Pneumocystis jiroveci Treatment: 15-20 mg/kg/day IV/PO divided q6-8h for 48hr then 7-10 mg/kg/day PO/IV divided q12h- Generally not recommended, but if required: 4-6 mg/kg/day IV/PO divided q12-24h

  • Pneumocystis jiroveci Treatment: 7-10 mg/kg/day IV/PO divided q12-24h

Pneumocystis jiroveci Treatment- 2.5-10 mg/kg IV/PO q24h; administer dose after dialysis on dialysis days


  • 4-6 mg/kg IV/PO three times weekly after dialysis if receiving dialysis three times weekly7-10 mg/kg IV/PO after dialysis three times weekly if receiving dialysis three times weekly

General Information

  •  Urinary tract infections

  •  Some superficial S. aureus infections (MRSA)

  •  Stenotrophomonas maltophilia infections

  •  Pneumocystis Pneumonia (PCP)

  • Nocardiosis

  • Prophylaxis for PCP and Toxoplasma gondii


  • Do not use for S. aureus bacteremia

  • Enterococci are resistant (even if reported as sensitive)

  • Streptococcus pyogenes: clinical failures occur even though may be reported as susceptible

Regular monitoring of kidney function and electrolytes if:

  • Prolonged use

  • Over age 65

  • Use of ACEi or ARB

  • K sparing diuretic

  • Baseline renal injury

  • Other risks for acute kidney injury/hyperkalemia

  • Renal injury and hyperkalemia, particularly in older patients (65 or older)

  • Sudden cardiac death: Higher risk in patients on angiotensin converting enzyme inhibitor (ACEi), angiotensin receptor blocker (ARB), K sparing diuretic (e.g. spironolactone)

  • Gastrointestinal upset common

  • Bone marrow suppression

  • Aseptic meningitis (rare)

  • Stevens Johnson syndrome/toxic epidermal necrolysis

  • Other rashes

  • Hepatitis

  • ACEi - Increased serum potassium level

  • Decreases cyclosporine

  • Methotrexate - Marrow suppression

  • Increases phenytoin

  • Increases INR with warfarin


  • Each mL of injectable contains sulfamethoxazole 80mg and trimethoprim 16mg


  • Each regular strength tablet contains sulfamethoxazole 400mg and trimethoprim 80mg

  • Each double-strength (DS) tablet contains sulfamethoxazole 800mg and trimethoprim 160mg

  • Each mL of oral suspension contains sulfamethoxazole 40mg and trimethoprim 8mg

Antimicrobial class: Sulfonamide - Antifolate

Pregnancy category: C

Average serum half life: 10 hours

Urine penetration: Therapeutic

Lung penetration: Therapeutic

CSF penetration: Therapeutic

Biliary penetration: Moderate

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