In vitro controlled release of isoniazid from poly (lactide-co-glycolide) matrices

Abstract In vitro release kinetics of isoniazid (INH) from a biodegradable polymeric matrix has been investigated for systems prepared under varying fabrication conditions. Matrices were prepared either by evaporation of co-solutions followed by extrusion under controlled temperature and pressure, or by dry mixing INH with PLGA which had been preground and sieved to isolate specific particle size ranges prior to extrusion. The effect on release kinetics of loading, polymer particle size, extrusion pressure, and rod diameter was explored. Fractional release as a function of time is shown to fit the Roseman-Higuchi model in that plots of (1 − F )ln(1 − F ) + F are linear with time where F is the fraction of drug released at time t . The effect of varying fabrication parameter values on the slope (identified as the combined rate constant for drug release, K = 4 CD / Aa 0 2 ) is as follows: K increases with decreasing polymer particle size, lower extrusion pressure, lower loading. The effect of increasing the rod diameter results in a small increase in K . Other parameter values being equal, solvent cast systems released more rapidly than those prepared without the use of solvent.