trimethoprim, Trimpex (Discontinued Brand), Proloprim (Discontinued Brand), Primsol (cont.)

Pharmacy Author:
Medical and Pharmacy Editor:

Taking trimethoprim with food may reduce some of these side effects. Trimethoprim may cause anemia due to a deficiency of folic acid. The anemia usually is mild and resolves when the trimethoprim is stopped. Patients who are folate-deficient, such as malnourished, alcoholic, geriatric, or pregnant patients, may be at greater risk for developing anemia with trimethoprim. Warning signs of anemia include white or bluish fingernails and unusual tiredness and weakness. Prolonged therapy can result in low platelet counts, low white blood cell counts, and other toxic effects on the blood cells.

Other important side effects are:

Rarely, the skin rash can progress to peeling or blistering. Some patients have photosensitivity reactions, that is, they develop skin rashes on parts of their body that are exposed to the sun.

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

PREPARATIONS: Tablets: 100 and 200 mg. Solution: 50 mg/5 ml

STORAGE: Tablets should be stored at room temperature, 15-30 C (59-86 F).

DOSING: The usual dose is 100 mg every 12 hours or 200 mg every 24 hours for 10 days. As with all antibiotics, it is important to complete the entire course of trimethoprim even if symptoms improve early during therapy. Persons with kidney diseases may need to receive lower doses since diseased kidneys may not eliminate trimethoprim adequately from the body, and levels of trimethoprim may increase in the body and lead to side effects.

DRUG INTERACTIONS: Changes in one patient's mental status occurred when a combination of trimethoprim and sulfamethoxazole was given with amantadine (Symmetrel). Blood levels of phenytoin (Dilantin) may be increased by treatment with trimethoprim. This may lead to side effects of phenytoin such as dizziness, and reduced attention. Trimethoprim also may increase blood levels of digoxin (Lanoxin) and warfarin (Coumadin) and lead to serious toxic effects. Anemia, due to a reduction in folic acid, can occur in persons receiving trimethoprim in combination with divalproex, valproic acid (Depakote, Depakote ER, Depakene, Depacon, Stavzor), methotrexate (Rheumatrex, Trexall), pyrimethamine, triamterene, or trimetrexate. The combination of trimethoprim and cyclosporine can increase the risk of kidney damage from cyclosporine. When trimethoprim and dapsone are used together, increased blood concentrations of both drugs can occur, sometimes with side effects that include a toxic condition of the blood called methemoglobinemia. Rifampin can increase the elimination of trimethoprim by the kidneys and may reduce the effectiveness of trimethoprim.

Medically Reviewed by a Doctor on 1/28/2015


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