Physicochemical and drug release characteristics of acetylated starches of five Lagenaria siceraria cultivars

Abstract

Modified starches play a crucial role in the pharmaceutical industries in controlling the drug release at a pre-determined rate. The effect of acetylation on the physicochemical and drug release characteristics of the starches from five different Indian L. siceraria cultivars was investigated. Starches isolated from the seeds of L. siceraria were subjected to varying degrees of acetylation. Using a range of characterization methods including amylose content, elemental analysis, light transmittance, swelling power, scanning electron microscopy, FT-IR and X-ray diffraction, the effect of acetylation was determined. The swelling power of starch acetates improved significantly (P<0.05) with the increase in degree of substitution. The increase in swelling shows that acetylation improved the accessibility of an amorphous area to the water. The formation of V-type of complex crystalline structures confirmed the acetylation of L. siceraria starch. Modification in the crystalline structure of starch acetate retarded the drug release, which is controlled by water uptake. The starch acetates from all the cultivars showed better sustained release properties with the increase in degree of substitution. Drug release through the swellable matrix was found to be controlled by fickian diffusion from the gel layer as indicated by Korsmeyer–Peppas models (R2) 0.9885–0.9984.