Formulation Optimization of Isoxsuprine HCl Sustained Release Tablet Using Full Factorial Design

Isoxsuprine hydrochloride, a β2 agonist used in peripheral vascular disease was formulated into sustain release matrix tablets, by wet granulation method using HPMC K15M as release retardant in different proportions and PVP K25 as a binder. The parameter optimized using 32 factorial designs. The tablets of all batches were evaluated for drug content, hardness, friability, weight variation and in vitro drug release profile. The dissolution profiles of formulated tablets were compared with a marketed product. The similarity factor (f2) was calculated to check the similarity with marketed product. Different dissolution models were applied to drug release data in order to evaluate release mechanisms and kinetics. Mathematical treatment of the in vitro drug release data suggests that, the drug release of all the formulations exhibited nearly zero-order kinetics, the release exponent n ranged from 0.69 to 0.8 indicate that drug release from the all batches occurred by non-Fickian diffusion mechanism (anomalous transport), i.e. the release is ruled by both diffusion of the drug and dissolution of the polymer. According to SUPAC guidelines the formulation containing combination of 25% HPMC K15M and 10% PVP K25 is the most similar formulation to marketed product.