An investigation into the effects of preparation conditions and storage on the rate of drug release from pharmaceutical glyceride bases.

The effects of preparation conditions on the release of theophylline from Gelucires 50/13 and 55/18 have been investigated. Samples were prepared by melting physical mixes under controlled conditions, followed by either slow or fast (ambient) cooling to the solid state. A rapid cooling rate was shown to result in a slower release rate for 2% w/w dispersions in Gelucire 55/18, with the slow- and fast-cooled systems resulting in drug release via a diffusion and a mixed diffusion/erosion mechanism, respectively. At higher drug loading (30% w/w), the cooling rate did not effect the release characteristics. The erosion of Gelucire 50/13 was found to be more rapid for slowly cooled samples. Viscosity measurements were used as a means of assessing the chemical stability of the Gelucires, with evidence being found for degradation of Gelucire 55/18 on storage following heat treatment, while Gelucire 50/13 appeared to be stable. The effects of storage on the dissolution profiles of ambiently cooled systems were studied, with drug release from both bases increasing on ageing for up to 180 days.