Availability of oxyphenbutazone from different suppository formulations.

The in vitro release of oxyphenbutazone as well as its rectal absorption in rabbits from different suppository formulations were investigated. It was proved that polyethylene glycol base gave higher medicament release than adeps solidus base. Incorporation of nonionic surfactants in Witepsol H 15 increased or decreased oxyphenbutazone release while incorporation of hydrophilic aerosil caused a reduction in the released amount of the medicament. A mixture of Witepsol H 15 or H 12 and Brij 58 (85:5) gave the highest in vitro release and the highest rectal absorption of the medicament. A correlation was found to exist between the in vitro release of oxyphenbutazone and its rectal absorption in rabbits.