THYROID AND MYOCARDIAL-FUNCTION AFTER REPLACEMENT OF CARBAMAZEPINE BYOXCARBAZEPINE

We determined changes in serum concentrations of thyroid hormones duri ng carbamazepine (CBZ) therapy during a 5-year prospective follow-up s tudy of 20 patients with newly diagnosed epilepsy. In addition, we eva luated the effects of replacing CBZ with oxcarbazepine (OCBZ) in 12 ma le patients with epilepsy in a 6-month prospective follow-up study. Ci rculating thyroxine and free thyroxine levels decreased after 2-month CBZ treatment and remained at a low level during the 5-year follow-up. There were no associated changes in serum thyrotropin (TSH) concentra tions. When CBZ was replaced by OCBZ, the function of the liver's P450 enzyme system normalized, as shown by an increase in antipyrine(T1/2) , and a decrease in antipyrine(CL). Serum total and free thyroxine lev els increased, and thereafter serum TSH levels decreased. Indexes of d iastolic heart function improved concomitantly, which may reflect subc linical hypothyroidism at the cellular level during CBZ treatment. We conclude that normal thyroid function can be restored in patients with epilepsy by replacing CBZ with OCBZ.