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Trimethoprim

    Brands

    DEA Class; Rx

    Common Brand Names; Primsol, Proloprim, TMP

    •  Antibiotics, Other

    Synthetic antifolate-type antiinfective agent. Has activity against gram-positive and gram-negative bacteria. Commonly used for UTI, prophylaxis of UTI, traveler’s diarrhea, and in combination with sulfamethoxazole or dapsone for prophylaxis and treatment of Pneumocystis infections.

    Indicated for the treatment of acute otitis media due to susceptible strains of S. pneumoniae or H. influenzae.

    Other Indications and Uses

    UTI caused by E. coli, Enterobacter spp., K. pneumoniae, P. mirabilis, coagulase-neg Staphylococcus spp.

    Hypersensitivity

    Megaloblastic anemia due to folate deficiency

    • Aseptic meningitis
    • Fever
    • Maculopapular rash (3-7% at 200 mg/day; incidence higher with larger daily doses)
    • Erythema multiforme
    • Exfoliative dermatitis
    • Pruritus (common)
    • Phototoxic skin eruptions
    • Stevens-Johnson syndrome
    • Toxic epidermal necrolysis
    • Hyperkalemia
    • Hyponatremia
    • Epigastric distress
    • Glossitis
    • Nausea
    • Vomiting
    • Leukopenia
    • Megaloblastic anemia
    • Methemoglobinemia
    • Neutropenia
    • Thrombocytopenia
    • Liver enzyme elevation
    • Cholestatic jaundice
    • BUN and creatinine increased
    • Anaphylaxis
    • Hypersensitivity reactions

    Decreases urinary potassium excretion; may cause hyperkalemia, particularly with high doses, renal insufficiency, or when combined with other drugs that cause hyperkalemia

    Large doses or long term therapy may interfere with hematopoiesis; the presence of clinical signs, such as sore throat, fever, pallor, or purpura may be early indications of serious blood disorders; monitor for signs/symptoms of hematologic disorders

    If clinical signs of blood disorder noted, obtain a complete blood count and discontinue drug if significant reduction in count of any blood element found

    Prolonged use may cause fungal or bacterial superinfection, including clostridium difficile-associated diarrhea and pseudomembranous colitis; may occur >2 months postantibiotic treatment

    Hypersensitivity reactions reported

    Use caution in patients with renal or hepatic impairment

    Use caution in patients with potential for folate deficiency, including malnourished, chronic anticonvulsant therapy, or elderly; folates may be administered concomitantly without interfering with antibacterial action of trimethoprim

    Some dosage forms may contain benzyl alcohol and derivatives; avoid in neonates

    Not indicated for prophylactic or prolonged administration in otitis media at any age

    Pregnancy Category: C

    Lactation: enters breast milk

    Adults

    200 mg/day PO is FDA-approved maximum dosage; however, doses up to 15 mg/kg/day PO have been used off-label for PCP in HIV-infected patients.

    Geriatric

    200 mg/day PO is FDA-approved maximum dosage; however, doses up to 15 mg/kg/day PO have been used off-label for PCP in HIV-infected patients.

    Adolescents

    400 mg/day PO is FDA-approved maximum dosage; however, doses up to 15 mg/kg/day PO have been used off-label for PCP in HIV-infected patients.

    Children

    10 mg/kg/day PO (Max: 400 mg/day) is FDA-approved maximum dosage; however, doses up to 15 mg/kg/day PO have been used off-label for PCP in HIV-infected patients.

    Infants

    6 to 11 months: 10 mg/kg/day PO is FDA-approved maximum dosage; however, doses up to 15 mg/kg/day PO have been used off-label for PCP in HIV-infected patients.
    1 to 5 months: Safety and efficacy have not been established; however, doses up to 15 mg/kg/day PO have been used off-label for PCP in HIV-infected patients.

    Neonates

    Safety and efficacy have not been established.

    Trimethoprim

    oral solution

    • 50mg/5mL

    tablet

    • 100mg