The influence of long-term anticonvulsant therapy with diphenylhydantoin and carbamazepine on serum gamma-glutamyltransferase, aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase.

In 110 patients receiving long-term anti-convulsant monotherapy with diphenylhydantoin (DPH) and carbamazepine (CBZ) the serum activities of gamma-glutamyltransferase (gamma-GT), aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase (AP) were examined retrospectively. Elevated serum levels of gamma-GT and AP were seen in 91% and 39% of patients receiving DPH therapy compared to 64% and 14% of those receiving CBZ treatment. With all enzymes evaluated increases were more frequent and higher with DPH treatment than with CBZ. Frequency and extent of increased activity of gamma-GT were highly related to daily dosage in both preparations. The proportion of pathological enzyme levels was associated with age in DPH and CBZ therapies but not found to be significant. Sex differences in the frequency of increased enzyme activities could not be demonstrated. The results are discussed in the context of induction of the cytochrome P-450 system.