Abstract

A natural gum, damar was investigated as a novel microencapsulating material for sustained drug delivery. Microparticles were prepared by oil-in-oil emulsion solvent evaporation method. Ibuprofen and diltiazem hydrochloride were used as model drugs. Microparticles were evaluated for particle size, encapsulation efficiency and in vitro drug release kinetics. Images of the microparticles were obtained by bright field microscopy. The effect of different gum:drug ratios and solubility of drug on microparticle properties was principally investigated. Gum damar could produce discrete and spherical microparticles with both drugs. With a freely water soluble drug (diltiazem hydrochloride), gum damar produced bigger (45-50 µm) and fast drug releasing microparticles with low encapsulation efficiencies (44-57%). Contrary, with a slightly water soluble drug (ibuprofen), gum damar produced small (24-33 µm) microparticles with better drug encapsulation (85-91%) and sustained drug delivery. The increase in gum:drug ratio showed an increase in particle size, encapsulation efficiency and decrease in drug release rate in all cases. Drug release profiles of all microparticles followed zero order kinetics. In conclusion, gum damar can be used successfully to produce discrete and spherical microparticles of ibuprofen and diltiazem hydrochloride.