Bioavailability of valproate after gastric and direct intestinal administration in rats.

1. The chemical characteristics of sodium valproate suggest that it might be absorbed from stomach as well as from intestine. 2. Absorption from these sites was assessed in rats by measuring plasma drug levels after administering [14C]-valproate or unlabelled valproate separately into (a) intact animals (by gavage), (b) ligated intestine, or (c) ligated stomach. 3. After gastric administration, mean plasma valproate at 1 h, and the mean area under the 0-3 h plasma radioactivity-time curves were 53% and 64% respectively, of the corresponding values after intestinal administration. 4. It is concluded that sodium valproate is absorbed from rat stomach, although at a slower rate than from the whole intestine.