Release rates of indomethacin from commercial witepsol suppositories and the bioavailabilities in rabbits and pigs.

Abstract

Releases of indomethacin from commercial witepsol suppositories were investigated by JP XI paddle, Muranishi and dialysis tubing methods. The drug was scarcely released from most of the suppositories by the paddle method at 37°C although it was released at 39°C. The release behaviors of suppositories differed greatly between the Muranishi and dialysis tubing methods. The melting points of suppositories correlated significantly with the release rates by the dialysis tubing method but not with those by the Muranishi method. The release rates by the Muranishi method were jelayed by increasing the fluid volume in the cylindrical cell and the releases by the dialysis tubing method were inhibited by adding aqueous medium into the tubing. The bioavailabilities from two and three of the products were estimated in rabbits and pigs, respectively, and the results correlated well with the release rates determined by the dialysis tubing method but poorly with those by the Muranishi method.