Single oral dose kinetics of zotepine and its relationship to prolactin response and side effects

The authors investigated the single oral dose kinetics of zotepine and its relationship with prolactin response and side effects in 14 healthy male volunteers. Each subject took a single oral 25-mg dose of zotepine, and plasma concentrations of zotepine, prolactin, and their side effects were monitored up to 36 hours after dosing. The means +/- SD of the time of maximal plasma concentration (tmax), the apparent oral clearance, the apparent volume of distribution, and the elimination half-life (t1/2) were 3.8 +/- 1.2 hours, 4.6 +/- 4.2 1/h.kg, 109.0 +/- 59.0 1/kg, and 21.0 +/- 8.9 hours, respectively. The change in prolactin concentrations and side effect scores were parallel with that of drug concentrations, although no significant correlation was found between these three parameters at any time-point. The current results clearly indicate that the tmax and t1/2 of zotepine are much longer than those previously reported, which are reflected in the changes in prolactin concentrations and side effect scores.