AN EVALUATION OF THE MECHANISMS OF DRUG-RELEASE FROM GLYCERIDE BASES

A series of dispersions containing theophylline in Gelucires 43/01, 54 /02, 50/02, 50/13 and 55/18 was prepared and the physical structures s tudied using differential scanning calorimetry. The dissolution, erosi on and swelling profiles of the drug dispersions were assessed. Geluci re 43/01 and 54/02 systems were found to release the drug by a simple diffusion mechanism, with no evidence for erosion or swelling being no ted. Gelucire 55/18, however, showed a more complex mechanism involvin g both diffusion and erosion. On increasing the drug load within the m atrices, the predominance of the erosion mechanism increased. Drug rel ease from Gelucire 50/13 matrices took place principally by erosion, a lthough the process was dominated by swelling and subsequent disintegr ation of the matrix, rather than simple dissolution of the base as was found for Gelucire 55/18. Gelucire 50/02 matrices also exhibited swel ling, although drug release occurred predominantly via diffusion. The study, therefore, demonstrates that Gelucires may release incorporated drugs by a number of mechanisms depending on the chemical composition of the base.