Trimethoprim 100 MG Oral Tablet
Generic Name: TRIMETHOPRIM
Brand Name: Trimethoprim
- Substance Name(s):
- TRIMETHOPRIM
WARNINGS
Serious hypersensitivity reactions have been reported rarely in patients on trimethoprim therapy.
Trimethoprim has been reported rarely to interfere with hematopoiesis, especially when administered in large doses and/or for prolonged periods.
The presence of clinical signs such as sore throat, fever, pallor or purpura may be early indications of serious blood disorders (see OVERDOSAGE: Chronic ).
Complete blood counts should be obtained if any of these signs are noted in a patient receiving trimethoprim and the drug discontinued if a significant reduction in the count of any formed blood element is found.
DRUG INTERACTIONS
Drug Interactions Trimethoprim may inhibit the hepatic metabolism of phenytoin.
Trimethoprim, given at a common clinical dosage, increased the phenytoin half-life by 51% and decreased the phenytoin metabolic clearance rate by 30%.
When administering these drugs concurrently, one should be alert for possible excessive phenytoin effect.
OVERDOSAGE
Acute Signs of acute overdosage with trimethoprim may appear following ingestion of 1 gram or more of the drug and include nausea, vomiting, dizziness, headaches, mental depression, confusion and bone marrow depression (see Chronic subsection).
Treatment consists of gastric lavage and general supportive measures.
Acidification of the urine will increase renal elimination of trimethoprim.
Peritoneal dialysis is not effective and hemodialysis is only moderately effective in eliminating the drug.
Chronic Use of trimethoprim at high doses and/or for extended periods of time may cause bone marrow depression manifested as thrombocytopenia, leukopenia and/or megaloblastic anemia.
If signs of bone marrow depression occur, trimethoprim should be discontinued and the patient should be given leucovorin; 5 to 15 mg leucovorin daily has been recommended by some investigators.
DESCRIPTION
Trimethoprim is a synthetic antibacterial available as 100 mg tablets for oral administration.
Trimethoprim is 2,4-Diamino-5-(3,4,5-trimethoxybenzyl) pyrimidine.
It is a white to cream colored, odorless, bitter compound.
The structural formula is represented below: C14H18N4O3 M.W.
290.32 Trimethoprim Tablets USP, 100 mg contain the following inactive ingredients: anhydrous lactose, colloidal silicon dioxide, magnesium stearate, sodium lauryl sulfate, sodium starch glycolate and stearic acid.
Trimethoprim Structural Formula
HOW SUPPLIED
Trimethoprim Tablets USP, 100 mg are scored, oval-shaped, white tablets imprinted DAN DAN and 5571.
They are available as follows: NDC 50268-775-15 10 tablets per card, 5 cards per carton.
Dispensed in blister punch material for Institutional Use Only.
Store at 20°-25°C (68°-77°F) in a dry place.
[See USP controlled room temperature.] Dispense in a tight, light-resistant container with a child-resistant closure.
GERIATRIC USE
Geriatric Use Clinical studies of trimethoprim tablets did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects.
Other reported clinical experience4,5 has not identified differences in response between the elderly and younger patients.
In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal or cardiac function, and of concomitant disease or other drug therapy.
Case reports of hyperkalemia in elderly patients receiving trimethoprim-sulfamethoxazole have been published.6 Trimethoprim is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function.
Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor potassium concentrations and to monitor renal function by calculating creatinine clearance.
INDICATIONS AND USAGE
For the treatment of initial episodes of uncomplicated urinary tract infections due to susceptible strains of the following organisms: Escherichiacoli, Proteus mirabilis, Klebsiella pneumoniae, Enterobacter species and coagulase-negative Staphylococcus species, including S.
saprophyticus.
Cultures and susceptibility tests should be performed to determine the susceptibility of the bacteria to trimethoprim.
Therapy may be initiated prior to obtaining the results of these tests.
PEDIATRIC USE
Pediatric Use Safety and effectiveness in pediatric patients below the age of 2 months have not been established.
The effectiveness of trimethoprim as a single agent has not been established in pediatric patients under 12 years of age.
PREGNANCY
Pregnancy Teratogenic Effects Pregnancy Category C.
Trimethoprim has been shown to be teratogenic in the rat when given in doses 40 times the human dose.
In some rabbit studies, the overall increase in fetal loss (dead and resorbed and malformed conceptuses) was associated with doses six times the human therapeutic dose.
While there are no large, well-controlled studies on the use of trimethoprim in pregnant women, Brumfitt and Pursell, 3 in a retrospective study, reported the outcome of 186 pregnancies during which the mother received either placebo or trimethoprim in combination with sulfamethoxazole.
The incidence of congenital abnormalities was 4.5% (3 of 66) in those who received placebo and 3.3% (4 of 120) in those receiving trimethoprim and sulfamethoxazole.
There were no abnormalities in the 10 children whose mothers received the drug during the first trimester.
In a separate survey, Brumfitt and Pursell also found no congenital abnormalities in 35 children whose mothers had received trimethoprim and sulfamethoxazole at the time of conception or shortly thereafter.
Because trimethoprim may interfere with folic acid metabolism, trimethoprim should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Nonteratogenic Effects The oral administration of trimethoprim to rats at a dose of 70 mg/kg/day commencing with the last third of gestation and continuing through parturition and lactation caused no deleterious effects on gestation or pup growth and survival.
NUSRING MOTHERS
Nursing Mothers Trimethoprim is excreted in human milk.
Because trimethoprim may interfere with folic acid metabolism, caution should be exercised when trimethoprim is administered to a nursing woman.
DOSAGE AND ADMINISTRATION
The usual oral adult dosage is 100 mg of trimethoprim every 12 hours or 200 mg trimethoprim (two 100 mg tablets) every 24 hours, each for 10 days.
The use of trimethoprim in patients with a creatinine clearance of less than 15 mL/min is not recommended.
For patients with a creatinine clearance of 15 to 30 mL/min, the dose should be 50 mg every 12 hours.