trimethoprim (TMP)

trimethoprim (TMP)

(trye meth' oh prim)

Primsol, Proloprim, Trimpex

Pregnancy Category C

Drug class

Antibacterial

Therapeutic actions

Inhibits the synthesis of nucleic acids and proteins in susceptible bacteria; the bacterial enzyme involved in this reaction is more readily inhibited than the mammalian enzyme.

Indications

·        Uncomplicated UTIs caused by susceptible strains of E. coli, Proteus mirabilis, Klebsiella pneumoniae, Enterobacter species, and coagulase-negativeStaphylococcus species, including Staphylococcus saprophyticus

·        Treatment of acute otitis media due to susceptible strains of S. pneumoniae and H. influenza in children

Contraindications and cautions

·        Contraindicated with allergy to trimethoprim, pregnancy (teratogenic in preclinical studies), megaloblastic anemia due to folate deficiency.

·        Use cautiously with hepatic or renal dysfunction, lactation.

Available forms

Tablets—100, 200 mg

Dosages

ADULTS

100 mg PO q 12 hr or 200 mg q 24 hr for 10–14 days for uncomplicated UTIs.

PEDIATRIC PATIENTS

·        Otitis media: 10 mg/kg/day in divided doses q 12 hr for 10 days.

GERIATRIC PATIENTS OR PATIENTS WITH RENAL IMPAIRMENT

For creatinine clearance of 15–30 mL/min, 50 mg PO q 12 hr; creatinine clearance of < 15 mL/min, not recommended.

Pharmacokinetics

Route	Onset	Peak
Oral	Varies	1–4 hr

Metabolism: Hepatic; T_1/2: 8–10 hr

Distribution: Crosses placenta; enters breast milk

Excretion: Urine

Adverse effects

·        Dermatologic: Rash, pruritus, exfoliative dermatitis

·        GI: Epigastric distress, nausea, vomiting, glossitis

·        Hematologic: Thrombocytopenia, leukopenia, neutropenia, megaloblastic anemia, methemoglobinemia, elevated serum transaminase and bilirubin, increased BUN and serum creatinine levels

·        Other: Fever

Nursing considerations

Assessment

·        History: Allergy to trimethoprim, megaloblastic anemia due to folate deficiency, renal or hepatic dysfunction, pregnancy, lactation

·        Physical: Skin color, lesions; T; status of mucous membranes; CBC; LFTs, renal function tests

Interventions

·        Perform culture and sensitivity tests before beginning drug therapy.

·        Protect the 200-mg tablets from exposure to light.

·        Arrange for regular, periodic blood counts during therapy.

·        WARNING: Discontinue drug and consult with physician if any significant reduction in any formed blood element occurs.

Teaching points

·        Take the full course of the drug; take all the tablets prescribed.

·        Have periodic medical checkups, including blood tests.

·        You may experience these side effects: Epigastric distress, nausea, vomiting (eat frequent small meals); rash (consult with your health care provider for appropriate skin care).

·        Report fever, sore throat, unusual bleeding or bruising, dizziness, headaches, rash.

Adverse effects in Italic are most common; those in Bold are life-threatening.