Protein binding of carbamazepine in epileptic patients.

The degree of protein binding of carbamazepine was evaluated in 45 mentally retarded epileptic patients. Although the mean percent unbound carbamazepine agreed with that obtained elsewhere, a wide interpatient variability was noted. There was a good correlation between unbound carbamazepine and total carbamazepine serum concentrations. The results of this study indicate that the total carbamazepine serum concentration must be interpreted with caution, and the unbound fraction may be a more appropriate therapeutic measure.