optimization and characterization of brinzolamide loaded biodegradable, amphiphilic poly-caprolactone-polyethylene glycol-poly-caprolactone (5000-1000-5000) tri-block co-polymeric carriers as long-acting intravitreal drug delivery vehicle for glaucoma therapy

The aim of this study was to formulate brinzolamide microparticles using a synthesized novel, biodegradable, amphiphilic and tri-block poly-caprolactone- polyethylene glycol-poly-caprolactone (5000–1000-1000) co-polymer by solvent evaporation technique. optimized the microparticles preparation was done using a 32-factorial design, with the amount of co-polymer (x1) and stirring speed (x2) as independent variables and assessed the responses of the particle sizes (y1), encapsulation efficiency (y2), and burst release (y3). other in vitro characterization tests like viscosity, ph, osmolarity, reconstitution time, water content by karl fisher titration, release kinetics, ftir spectroscopy, differential scanning calorimetry, x-ray diffraction, gas chromatography, thermogravimetric analysis, 1h-nmr, and 13c-nmr spectroscopy were performed. encapsulation efficiency reached 68.32±1.63% under optimal conditions (x1 = 101 mg, x2 = 729 rpm), with a 66.77±3.43 μm size range and a burst release rate of 12.89±8.38%. in phosphate-buffer saline at ph 7.4, the in vitro drug release was sustained up to 10 days with zero order kinetics. all results were satisfactory and the hydroxyl end cap and 91:09 molar ratio of caprolcatone and ethylene glycol for formed microparticles were confirmed by 1h-nmr and 13 c-nmr.  in summary the developed novel, biodegradable, and injectable micro-particles have the potential for long-acting brinzolamide release for intra-vitreal drug delivery.