Pharmacokinetics of the antidepressant drug viloxazine in normal subjects and in epileptic patients receiving chronic anticonvulsant treatment.

In order to evaluate the influence of chronic antiepileptic drug treatment on the kinetics of the antidepressant viloxazine (VLX), six drug-free control subjects and six epileptic patients treated with one or two anticonvulsants (phenobarbital, carbamazepine or phenytoin) were given a single oral dose of VLX (200 mg). On a separate occasion, the patients were also given 200 mg VLX by IV infusion. Plasma VLX levels were determined by GLC. Following oral dosing, VLX was rapidly absorbed from the gastrointestinal tract (peak levels at 0.5-4 h); plasma level profiles showed a considerable interindividual variability but did not differ significantly between patients and controls. Terminal half-lives were 4.3 +/- 1.5 h in the patients and 4.3 +/- 1.8 h in the controls. Clearance and volume of distribution calculated after IV dosing in the patients were 124 +/- 11 ml h-1 kg-1 and 0.73 +/- 0.28 l/kg, respectively. The absolute oral availability was 85 +/- 14%. At variance with findings reported for other antidepressants, VLX kinetics do not appear to be significantly altered by concurrent treatment with enzyme-inducing antiepileptic drugs.