Rate‐controlled rectal absorption enhancement of cefoxitin by co‐ administration of sodium salicylate or sodium octanoate in healthy volunteers

1. The effects of sodium octanoate and sodium salicylate on the rectal absorption of cefoxitin were investigated in healthy volunteers. Drug solutions were given either as a bolus or as a zero‐order infusion. 2. On rectal infusion sodium octanoate and sodium salicylate both enhanced mean cefoxitin bioavailability (+/‐ s.d.) from 5.0 +/‐ 1.2% to 9.1 +/‐ 1.3% and 9.2 +/‐ 1.5%, respectively. After rectal bolus delivery octanoate increased the mean cefoxitin bioavailability from 7 +/‐ 3% to 17 +/‐ 3%, whereas bolus salicylate did not produce a statistically significant effect. All formulations were well tolerated by the volunteers. 3. It is concluded that both octanoate and salicylate are capable of enhancing rectal cefoxitin absorption in man; rate of delivery seems to be an important factor.