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 pharmacodynamics of zonisamide, an antiepileptic drug, were investigated in rats. Absorption of oral zonisamide was significantly inhibited by exposure to cigarette smoke. The Cmax, T1/2 and the area under the plasma concentration-time curve 0-24 values in the cigarette smoke exposure group were significantly lower than those in the control group. Although tonic extension (TE) induced by maximal electroshock was completely blocked by the administration of zonisamide in the control group, 50% of rats showed TE in the cigarette smoke exposure group. Exposure to cigarette smoke influences both the pharmacokinetics and antiepileptic effects of zonisamide. The effects of smoking on epileptic patients using zonisamide warrants further attention.