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 f rom Gelucires 50/13 and 55/18 have been investigated. Samples were pre pared by melting physical mixes under controlled conditions, followed by either slow or fast (ambient) cooling to the solid state. A rapid c ooling rate was shown to result in a slower release rate for 2% w/w di spersions in Gelucire 55/18, with the slow- and fast-cooled systems re sulting 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 Geluc ire 50/13 was found to be more rapid for slowly cooled samples. Viscos ity measurements were used as a means of assessing the chemical stabil ity of the Gelucires, with evidence being found for degradation of Gel ucire 55/18 on storage following heat treatment, while Gelucire 50/13 appeared to be stable. The effects of storage on the dissolution profi les of ambiently cooled systems were studied, with drug release from b oth bases increasing on ageing for up to 180 days.