Studies on Almond Gum and Gelucire-Based Pellets Prepared by Extrusion and Spheronization for Sustained Release

The aim of the investigation was to prepare sustained release (SR) pellets of diltiazem hydrochloride employing almond gum and gelucire. The study was performed to explore the suitability of almond gum in the preparation of pellets of diltiazem hydrochloride without the use of microcrystalline cellulose and role and effectiveness of hydrophobic gelucire (43/01) in controlling the drug release.

Pellets were prepared by extrusion-spheronization of the blend previously obtained by incorporation of the drug in a mixture of melted gelucire 43/01 and almond gum. A 3² factorial design was employed to study the effect of two independent variables, almond gum and gelucire, on the size, friability and drug release from pellets. Scanning electron microscopy, differential scanning calorimetry and infrared spectroscopy were performed to characterize pellets.

Free flowing spherical pellets could be prepared. The 3² factorial study revealed that as the proportion of almond gum increased, the size of pellets increased, while increasing gelucire had opposite effect. The yield of pellets prepared in different formulations is in the range of 86 to 92%. The size of the pellets varied from 1128 to 1458 μ. Higher amounts of gelucire resulted in pellets with greater friability, whereas increasing the amount of almond gum yielded pellets with low friability. The pellets exhibited SR of diltiazem and the presence of gelucire in the matrix of the pellets had an enhanced sustaining effect on release.

Dispersion of the drug in gelucire before it was converted to pellets resulted in extended release of drug. The drug release rate changed with changes in the proportion of pellet composition. The results of the study suggest that employing gelucire (43/01) in the preparation of pellets is a useful approach in the design of SR products of highly water-soluble drug such as diltiazem hydrochloride.