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

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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.

PREGNANCY: Although there are no human studies that have examined the effects of trimethoprim on the fetus, animal studies have shown adverse effects. Therefore, the physician must weigh the potential risks to the fetus against the potential benefits to the mother when considering trimethoprim therapy for pregnant women.

NURSING MOTHERS: Trimethoprim is secreted into breast milk in high concentrations. Use of trimethoprim by mothers who are breast-feeding should be avoided.



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