Influence of fat composition on the melting behaviour and on the in vitro release of indomethacin suppositories

Abstract Thermal analysis was used to determine the influence of monoglycerides, a fatty acid-fatty acid methyl ester blend, fatty acid polyethylene glycol esters and indomethacin on the melting behaviour and hardening of triglyceride suppository bases. The influence of these additives on the in vitro release of indomethacin was also investigated. A correlation was seen between the melting point of the monoglycerides and the increase in melting point of the added triglyceride. The addition of indomethacin always resulted in higher melting temperatures. No important influence of the additives and the drug was observed on the hardening behaviour of the suppository bases. Indomethacin release, in vitro, was higher for polyethylene glycol and Suppocire AP formulations than for all other bases. The chemical composition and melting point of the monoglycerides added to the triglyceride can influence the in vitro release of indomethacin. Fatty acid-fatty acid methyl ester blends increased the release of indomethacin only when they were added to a lauric triglyceride (Witepsol H 15).