Cross-linking<i> Enset</i> Starch Microspheres, Physicochemical Characterization and Study on Their Drug Loading and Release Properties

Abstract

Enset starch was cross-linked in solid phase systems using sodium hexametaphosphate (SHMP) as crosslinking agent under different microwave powers and reaction times to investigate its drug-release-sustaining ability. Paracetamol was used as a model drug. The swelling and water-binding capacities and the peak viscosity of the cross-linked enset starch varied with cross-linking parameters. The degree of cross-linking (DC) also varied with reaction time. The drug loading ratio (D) and encapsulation efficiency (E) of the crosslinked starch increased significantly compared to the native starch. Loading time markedly affected the two parameters. Increasing loading time from 45 to 150 min boosted the D and E, respectively, from 4.7 to 10.4% and 9.4 to 20.7%. Drug concentration in the loading medium affected both parameters but in the opposite way. Native enset starch matrices loaded with the model drug released 96.4% of their content within 1.5 h while the cross-linked ones released only 39.5%. After 24 h, cross-linked enset starch matrices released 95.6% of the drug implying their ability to sustain drug release, and hence their potential use as drug-release-sustaining pharmaceutical excipient. Keywords: enset starch, degree of cross-linking, loading ratio, encapsulation efficiency, drug-release