Trimethoprim/Sulfamethoxazole

DEA Class; Rx

Common Brand Names; Bactrim, Bactrim DS, Septra, Septra DS, Cotrim, cotrimoxazole, Sulfatrim

  • Sulfonamides; 
  • Antibiotics, Combos

Combination product of trimethoprim and sulfamethoxazole in a fixed 1:5 ratio; both are synthetic folate antagonists.

Indicated for acute exacerbations of chronic bronchitis due to susceptible strains of Streptococcus pneumoniae or Haemophilus influenzae

Documented Pneumocystis jiroveci pneumonia (PCP); also, prophylaxis against PCP in individuals who are immunosuppressed

Enteritis caused by susceptible strains of Shigella flexneri and S sonnei

Traveler’s diarrhea due to susceptible strains of enterotoxigenic Escherichia coli

UTIs caused by susceptible strains of Escherichia coli, Klebsiella species, Enterobacter species, Morganella morganii, Proteus mirabilis, and Proteus vulgaris

Also indicated for

  • Acne Vulgaris (Off-label)
  • Community Acquired Pneumonia (Off-label)
  • Sepsis
  • Meningitis, Bacterial

Known hypersensitivity

Age <2 months

CrCl <15 mL/min when renal function status cannot be monitored

Documented megaloblastic or folate deficiency anemia

Significan hepatic impairment

Contraindicated in pregnant patients at term and in nursing mothers, because sulfonamides, which pass the placenta and are excreted in the milk, may cause kernicterus

History of drug-induced immune thrombocytopenia with use of trimethoprim and/or sulfonamides

Concomitant administration with dofetilide

  • Anorexia
  • Nausea
  • Vomiting
  • Vertigo
  • Seizure
  • Peripheral neuritis
  • Erythema multiforme
  • Hyperkalemia
  • Rash
  • Urticaria
  • Immune hypersensitivity reaction
  • Stevens-Johnson syndrome
  • Toxic epidermal necrolysis
  • Agranulocytosis
  • Aplastic anemia
  • Hyponatremia
  • Disorder of hematopoietic structure
  • Fulminant hepatic necrosis

Not for use in areas with resistance rates >10%

Severe and symptomatic hyponatremia can occur in patients receiving sulfamethoxazole/ trimethoprim, particularly for treatment of P. jirovecii pneumonia; evaluation for hyponatremia and appropriate correction is necessary in symptomatic patients to prevent life-threatening complications

If patient treated for Pneumocystis jirovecii develops skin rash, fever, leukopenia, or any other sign of adverse reaction, therapy or re-challenge should be re-evaluated

Circulatory shock with fever, severe hypotension, and confusion requiring intravenous fluid resuscitation and vasopressors has occurred within minutes to hours of re-challenge with trimethoprim-sulfamethoxazole in patients with history of recent (days to weeks) exposure to sulfamethoxazole-trimethoprim

Fatalities associated with the administration of sulfonamides, although rare, have occurred due to severe reactions, including severe cutaneous adverse reactions (SCARs), including Stevens-Johnson Syndrome, toxic epidermal necrolysis, drug reaction with eosinophilia and systemic symptoms (DRESS), acute generalized exanthematous pustulosis (AGEP) and acute febrile neutrophilic dermatosis (AFND), fulminant hepatic necrosis, agranulocytosis, aplastic anemia and other blood dyscrasias; clinical signs, such as rash, sore throat, fever, arthralgia, pallor, purpura or jaundice may be early indications of serious reactions; discontinue therapy at first appearance of skin rash or any sign of serious adverse reaction

Acute and delayed lung injury; anaphylaxis and circulatory shock have occurred with administration of sulfamethoxazole and trimethoprim products

Cough, shortness of breath and pulmonary infiltrates potentially representing hypersensitivity reactions of the respiratory tract reported in association with sulfamethoxazole and trimethoprim treatment

Severe pulmonary adverse reactions occurring within days to week of initiation of treatment and resulting in prolonged respiratory failure requiring mechanical ventilation or extracorporeal membrane oxygenation (ECMO), lung transplantation or death also reported in patients and otherwise healthy individuals treated with sulfamethoxazole and trimethoprim products

Caution when used in elderly individuals; risk of bone marrow suppression

Therapy may cause fetal harm if administered to pregnant woman; some epidemiologic studies suggest that exposure to drug during pregnancy may be associated with increased risk of congenital malformations, particularly neural tube defects, cardiovascular abnormalities, urinary tract defects, oral clefts, and club foot

Levels of drug in breast milk are approximately 2 to 5% of recommended daily dose for pediatric patients over two months of age

All doses are based on trimethoprim component.

Adults

20 mg/kg/day PO (Max: 1,600 mg/day); 20 mg/kg/day IV (Max: 960 mg/day).

Geriatric

20 mg/kg/day PO (Max: 1,600 mg/day); 20 mg/kg/day IV (Max: 960 mg/day).

Adolescents

20 mg/kg/day PO (Max: 1,600 mg/day); 20 mg/kg/day IV (Max: 960 mg/day).

Children

20 mg/kg/day PO (Max: 1,600 mg/day); 20 mg/kg/day IV (Max: 960 mg/day).

Infants

2 to 11 months: 20 mg/kg/day PO/IV.
younger than 2 months: Contraindicated in infants younger than 2 months of age; however, doses up to 10 mg/kg/day PO are used off-label for PCP prophylaxis in HIV-infected/exposed infants as young as 4 weeks of age.

Neonates

Contraindicated in infants younger than 2 months of age; however, doses up to 10 mg/kg/day PO are used off-label for PCP prophylaxis in HIV-infected/exposed infants as young as 4 weeks of age.

Trimethoprim/sulfamethoxazole

injected solution

  • (16mg/80mg)/mL

oral suspension

  • (40mg/200mg)/5mL

tablet

  • 80mg/400mg
  • 160mg/800mg

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