Ketorolac tromethamine and ketoprofen suppositories: release profiles and bioavailability of a cocoa butter base formula in rabbits.

Ketorolac tromethamine suppositories (30 mg) and ketoprofen suppositories (50 mg) were made by the fusion method with various bases such as cocoa butter, Witepsol H15, Witepsol W25, Witepsol W35, Witepsol E75, Suppocire AML and Hydrokote AP5-1. Also, ketorolac tromethamine and ketoprofen suppositories were prepared using Eudragit L100 and propylene glycol. The release rates for both ketorolac tromethamine and ketoprofen suppositories in Sorensen's phosphate buffer pH 7.4 were determined and found to be: cocoa butter greater than Witepsol H15 greater than Witepsol W25 greater than Suppocire AML greater than witepsol W35 greater than Hydrokote AP5-1> Witepsol E75. Drug-release studies showed that ketorolac tromethamine demonstrates faster release profiles from these selected bases in comparison to those seen for ketoprofen. Analysis of the relaease kinetics for ketorolac tromethamine and ketoprofen from the various bases suggests that a combination of release mechanisms such as melting of the base followed by partititoning of the drug, along with some diffusion of the drug from the base to the dissolution media, seems to be operative in these systems. The absolute bioavailabilty of the suppository formulaion made with ketorolac tromethamine in cocoa butter base was found to be 61% in rabbits.