CARBAMAZEPINE AND PHENYTOIN
Some reports describe rises in serum phenytoin levels, with toxicity, whereas others describe falls in phenytoin levels. Genetic differences in the metabolism of these drugs may be an explanation for the differences. Falls in carbamazepine serum levels, sometimes with rises in carbamazepine-epoxide levels, have been described.
Monitor antiepileptic levels during concurrent use (where possible including carbamazepine-epoxide, the active metabolite of carbamazepine) so that steps can be taken to avoid the development of toxicity or lack of efficacy. Not all patients appear to have an adverse interaction, and, at present, it does not seem possible to identify those potentially at risk.
Monitor antiepileptic levels during concurrent use (where possible including carbamazepine-epoxide, the active metabolite of carbamazepine) so that steps can be taken to avoid the development of toxicity or lack of efficacy. Not all patients appear to have an adverse interaction, and, at present, it does not seem possible to identify those potentially at risk.