The effects of exposure to cigarette smoke on the pharmacokinetics and pharmacodynamics of zonisamide in rats

The effects of exposure to cigarette smoke on the pharmacokinetics and phar macodynamics of zonisamide, an antiepileptic drug,were investigated in rats . Absorption of oral zonisamide was significantly inhibited by exposure to cigarette smoke. The Cmax, t(1/2) and the area under the plasma concentrati on-time curve 0-24 values in the cigarette smoke exposure group were signif icantly lower than those in the control group. Although tonic extension (TE ) induced by maximal electroshock was completely blocked by the administrat ion of zonisamide in the control group, 50% of rats showed TE in the cigare tte smoke exposure group. Exposure to cigarette smoke influences both the p harmacokinetics and antiepileptic effects of zonisamide. The effects of smo king on epileptic patients using zonisamide warrants further attention.