What effect does Phenytoin have in relation to folate?

Phenytoin is an antiepileptic medication that is known to have an impact on folate metabolism. Specifically, it decreases folate levels in the body. This occurs because phenytoin interferes with the absorption and metabolism of folate, leading to a reduction in its serum levels. Phenytoin can inhibit the enzyme dihydrofolate reductase, which is crucial for converting folate into its active form. Additionally, phenytoin can also lead to increased metabolism of folate through its effects on liver enzymes, further contributing to lower folate levels.

This decrease in folate can result in various clinical implications, such as the potential development of megaloblastic anemia due to folate deficiency, particularly in patients who are on long-term phenytoin therapy. Monitoring folate levels and considering supplementation may be advisable in patients taking phenytoin to prevent such deficiencies and associated complications.