Optimization of Floating Microspheres of Captopril Using Full Factorial Design

Captopril is an angiotensin converting enzyme inhibitor, widely used inmanagement of hypertension. It has very short half life of 2 h and oralbioavailability of 70%. The present investigation is concerned with thedevelopment of the floating microspheres of Captopril to target the drug toits absorption site by increasing the residence time of drug in stomach and tocontrol drug release in therapeutic range for longer period of time. Floatingmicrospheres of Captopril were prepared by Non-aqueous solventevaporation technique using 32- Full factorial design. In this dosage form,hydrophobic water impermeable polymer (EC) for controlling the release ofdrug and hydrophobic water permeable polymer (Eudragit RL-100) were usedfor initial release of drug. Optimization process was carried out with respectto various dependent variables like T50%(h),T80% (h), log K of Pappas eq.,release at 12 h, release at 18 h, K of 1st order etc. and optimized formulationswere developed. Among three optimized formulations, results of OF1 andOF2 closely met to targeted data while OF3 was found to be best formulationas per cost-effectiveness which also showed significant results to targeteddata. Two months of stability study was carried out at room temperature forall three optimized formulations and results showed no significant changes inpercentage drug entrapment efficiency and in-vitro drug release study afterstability study. So the all three optimized formulation containing 50 mg ofCaptopril, released drug for 24 h within desired therapeutic concentration