Formulation development and evaluation of pirenzepine floating microspheres

Abstract

The current study investigates the development and evaluation of floating microspheres using Pirenzepine as a model  drug  to  prolong gastric retention time.  Floating microspheres were  prepared by ionotropic gelation method using sodium alginate as polymer, Calcium chloride as cross linking agent, sodium bicarbonate as gas generating agent and HPMCK4M, HPMCK15 M as rate retarding agent in concept to optimize the formulation. The FTIR studies indicated no significant interaction observed between drug and excipients. The F7 formulation showed the excellent flow properties. The particle size, % yield, % entrapment efficiency and swelling index of optimized  formulation  was  investigated  55.45±0.09µm,  96.10%,  96.30%  and  95.12%,  respectively.  The %buoyancy was excellent with approximately 98.10% of the microspheres floating upto 24h. The Cumulative % drug released from F7 microspheres was found to be 96.23±0.11% with in 12h and compared with the marketed product 95.23±0.21% with in 1h. The optimized formulation best fitted into zero order and Higuchi kinetics indicating diffusion controlled drug release  pattern. SEM studies showed spherical shape and  revealed the presence of pores on the floating microspheres surface which was responsible for floating ability. Optimized microspheres (F7) was stable at 40°C ± 2°C/75% RH ± 5% RH  for 6 months. The F7 formulation showed the better results with HPMC K4M compared with HPMC K15M as rate retarding polymer. These results indicated that the Pirenzepine-loaded microspheres could potentially be exploited as a delivery system with controlled drug release and improved insitu bioavailability.