Formulation Design and Optimization of Theophylline Microspheres Containing Akidi Beans (<i>Vigna Unguiculate</i>) Starch as Polymer Using Central Composite Design

Abstract

The aim of the study was to use central composite design in formulating theophylline microspheres containing Akidi beans (Vigna unguiculata L Warp) starch as a controlled-release polymer. Theophylline microspheres containing pregelatinized Akidi beans starch, alginate and chitosan were prepared using ionic gelation. A 2 factor, 2 Level central composite design was used with starch:alginate ratio (X₁) and polymer:drug ratio (X₂) as variables, and size, entrapment efficiency and quantity of drug released in 12 h, Q₁₂, as responses. Regression parameters and response surface plots were generated. The microspheres were spherical with size 1.68 00 ± 0.12 – 1.95 ± 0.03 mm. Optimized formulation containing 4:1 Akidi starch: alginate and 3:1 polymer: drug ratios, prepared according to levels determined by Minitab software using desirability function, showed significant increase in the responses in comparison to those containing alginate alone. Akidi beans starch demonstrated good potential as an alternative polymer for the controlled delivery of drugs.

Key words: Akidi beans starch, central composite design, controlled release, desirability function, sodium alginate, theophylline microspheres