Influences of exposure to cigarette smoke on concentration of nicorandil in plasma of rats.

Influences of acute exposure to cigarette smoke on plasma concentrations of nicorandil administered orally and parenterally were investigated in rats by HPLC. The animals were exposed to tobacco smoke of two kinds of cigarettes using a smoking machine (i.e., the cigarette smoke contained either low or high nicotine and tar). The plasma concentration of nicorandil administered orally at a dose of 10 mg/kg had a lower absorption phase in two cigarette smoke-exposed groups, particularly in the high nicotine and tar-containing cigarette smoke-exposed group, compared with the nonsmoking control group. The AUC and MRT values in a high nicotine and tar-containing cigarette smoke-exposed group were lower and higher, respectively, than in the nonsmoking control group. However, there was no marked difference in nicorandil plasma concentrations between the cigarette smoke-exposed group and the nonsmoking control group when nicorandil was administered ip or iv at a dose of 5 mg/kg. These results suggest that cigarette smoke exposure causes the suppression or delay of absorption of nicorandil from the gastrointestinal tract.