Trimethoprim Dosage

This dosage information may not include all the information needed to use Trimethoprim safely and effectively. See additional information for Trimethoprim.

The information at Drugs.com is not a substitute for medical advice. ALWAYS consult your doctor or pharmacist.

Usual Adult Dose for:

Usual Pediatric Dose for:

Additional dosage information:

Usual Adult Dose for Urinary Tract Infection

Acute uncomplicated infections: 100 mg orally every 12 hours or 200 mg orally every 24 hours for 10 days

Usual Adult Dose for Cystitis Prophylaxis

(Not approved by FDA)

100 mg orally at bedtime for 6 weeks to 6 months

Usual Adult Dose for Pneumocystis Pneumonia

(Not approved by FDA)

Centers for Disease Control and Prevention (CDC) recommendations:
HIV-infected patients: 15 mg/kg/day orally in 3 divided doses (in addition to dapsone 100 mg daily) for 21 days

Trimethoprim with dapsone is recommended as alternative treatment of mild-to-moderate Pneumocystis jirovecii pneumonia.

Usual Pediatric Dose for Otitis Media

Acute infections:
6 months or older: 5 mg/kg orally every 12 hours for 10 days

Usual Pediatric Dose for Urinary Tract Infection

Acute uncomplicated infections:
12 to 18 years: 100 mg orally every 12 hours or 200 mg orally every 24 hours for 10 days

(Not approved by FDA)

2 months to less than 12 years: 2 to 3 mg/kg orally every 12 hours for 10 days

Usual Pediatric Dose for Pneumocystis Pneumonia

(Not approved by FDA)

CDC recommendations:
HIV-infected adolescents: 15 mg/kg/day orally in 3 divided doses (in addition to dapsone 100 mg daily) for 21 days

Trimethoprim with dapsone is recommended as alternative treatment of mild-to-moderate Pneumocystis jirovecii pneumonia.

Renal Dose Adjustments

CrCl 15 to 30 mL/min: Usual dose should be reduced by 50%.
CrCl less than 15 mL/min: Not recommended.

Liver Dose Adjustments

Caution is recommended in patients with hepatic impairment.

Precautions

Trimethoprim is contraindicated in patients with documented megaloblastic anemia due to folate deficiency.

High doses and/or prolonged use of trimethoprim may cause bone marrow depression manifested as thrombocytopenia, leukopenia, and/or megaloblastic anemia.

Trimethoprim should be discontinued in patients if early symptoms of blood dyscrasias develop (sore throat, fever, pallor, or purpura) and if significant abnormalities in blood counts are found.

Monitoring of potassium concentrations is recommended, especially in elderly patients.

Safety and effectiveness have not been established in pediatric patients less than 2 months of age. Effectiveness in the treatment of acute otitis media has not been established in pediatric patients less than 6 months of age. The efficacy of trimethoprim as a single agent in the treatment of urinary tract infection has not been established in pediatric patients less than 12 years of age.

Dialysis

CrCl less than 15 mL/min: Not recommended.

Peritoneal dialysis is not effective and hemodialysis only moderately effective in eliminating trimethoprim.

Other Comments

Trimethoprim can interfere with serum methotrexate assays by the Competitive Binding Protein Technique (CBPA) when a bacterial dihydrofolate reductase is used as the binding protein. There is no interference with methotrexate radioimmunoassays (RIA). Trimethoprim may also interfere with creatinine assays using the Jaffe alkaline picrate reaction, resulting in 10% overestimations of the range of normal values.

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