Design and Evaluation Of Ibuprofen-Loaded Microspheres Using Acid-Thinned Sweet Potato Starch As A Co-Polymer For Controlled Release

Microsphere formulations can control the delivery of drugs in a sustained manner using polymers as carriers. Combining indigenous sweet potato starch (SP) with commercial polymers such as sodium alginate and hydroxypropyl methylcellulose (HPMC) produces microspheres with improved properties, including drug entrapment and release. This study aims to explore the use of acid-thinned starch of SP as a more affordable, release-retarding copolymer in ibuprofen microspheres. The microspheres were prepared by the ionic gelation method using acid-thinned SP starch in combination with sodium alginate and HPMC at ratios 1.0:1.0:1.0, 1.5:1.0:0.5. 1.5:0.5.1.0, and at polymer: drug ratios 3.0:1.0; 4.0:1.0 and 6.0:1.0. The microspheres were characterized for morphology, swelling index, entrapment efficiency and dissolution time (t50).  A 32 factorial design was used to analyse the influence of polymer blend type and polymer: drug ratio on these properties. Spherical microspheres with size range of 0.56±0.03 to 0.92 ±0.09 mm was obtained. FT-IR analysis revealed ibuprofen was well entrapped with no incompatibility between the drug and the polymer blends. Entrapment efficiency ranged from 74.00±4.35 to 90.00±6.00 %. The time taken for 50% drug release (t50) was 4.00±0.15 to 10.00±0.87 h. Polymer type and polymer: drug ratio had positive influence on size, entrapment and t50 (p < 0.05). Formulation F9 containing starch: alginate: HPMC, 1.5:0.5:1.0, with polymer: drug ratio of 6.0:1.0, was the optimized formulation with acceptable particle size, swelling, highest entrapment, and the most sustained drug release. Acid-thinned sweet potato starch showed potential as a copolymer for controlled delivery of ibuprofen in microspheres.