Effects of phenothiazines and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide on rat colonic absorption of cefmetazole.

Rat colonic absorption of cefmetazole was increased significantly by calmodulin inhibitors such as phenothiazines and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) when they were coadministered at a concentration between 1 and 100 microM. The bioavailability of cefmetazole, determined by area under the blood concentration curve method, increased 20 to 30% by the coadministration of calmodulin inhibitors. It is speculated that the enhancing action of agents on rat colonic absorption of cefmetazole takes place by a paracellular route and coadministration of sodium ion increases their actions.