A patient is about to begin treatment with isoniazid. The nurse learns that the patient also takes phenytoin (Dilantin) for seizures. The nurse will contact the provider to discuss:

Question

Quizplus · Accepted Answer

Isoniazid is a strong inhibitor of three cytochrome P450 enzymes, and inhibition of these enzymes can raise the levels of other drugs, including phenytoin. Patients taking phenytoin should have the levels of this drug monitored, and the dose should be reduced if appropriate. Reducing the dose of isoniazid is not indicated. It is not necessary to monitor isoniazid levels.

A Patient Is About to Begin Treatment with Isoniazid