Study on Effect of Formulation Variables on Drug Release of Bosentan Microspheres

ABSTRACT: The scope of the study was to examine the effect of stirring speed and polymer ratio on characteristics of Bosentan (BOS) microspheres. In the present study BOS microsphere formulations were prepared by ionotropic gelation process using Sodium alginate, and polymers Hydroxypropyl methyl cellulose (HPMC) K15 and Eudragit RL 100, either alone or in combination at different compositions. A total of twenty-four formulations were developed, with twelve prepared at 400 rpm and twelve at 600 rpm. The effects of drug-polymer ratio and stirring speed on practical yield, particle size, entrapment efficiency (EE), and in vitro drug release were investigated. The practical yield of formulations prepared at 600 rpm ranged from 82.6 ± 1.15% to 92.3 ± 1.37%, while at 400 rpm, it ranged from 80.2 ± 1.62% to 90.1 ± 1.26%. The particle size of formulations prepared at 600 rpm ranged between 167.2 ± 1.34 µm and 192.8 ± 1.021 µm, whereas at 400 rpm, it was found to be between 186.9 ± 1.03 µm and 204.9 ± 1.05 µm. The entrapment efficiency (EE) for F1–F12 at 600 rpm was 72.5 ± 1.37% to 84.1 ± 0.92%, while at 400 rpm, it ranged from 79.8 ± 0.25% to 90.8 ± 0.42%. Among all the formulations, F6, prepared at 600 rpm, was identified as the optimized formulation as it had an optimal particle size of 172.9 ± 1.05 µm and an EE of 84.1 ± 0.92%. It also achieved 100% drug release within 12 hours in a controlled and predetermined manner. The results indicated that the combination of HPMC K15 and Eudragit RL 100 at optimal concentrations, along with higher stirring speeds, significantly enhanced drug release characteristics.