Effect of the formulation parameters on the encapsulation efficiency and release behavior of p-aminobenzoic acid-loaded ethylcellulose microspheres

Abstract

In the current study, p-aminobenzoic acid-loaded ethylcellulose mic­rospheres were prepared under various conditions by the solvent evaporation method (o/w). This preparation was performed with different p-aminobenzoic acid:ethylcellulose (PABA:EC) ratios, stirring speeds, surfactant nature and concentrations in order to investigate their effect on the encapsulation effi­ciency and drug release kinetics. Scanning electron microscopy (SEM) studies showed spherical microspheres with a porous surface and different structures. The mean Sauter diameter (d32) of these microparticles was in the range from 47 to 165 µm with PVA and from 793 to 870 µm with Tween 80 by adjusting process parameters. However, the encapsulation efficiency varied from 37.52 to 79.05 % suitable for the adjustment of a p-aminobenzoic acid with pro­longed release. The microspheres were characterized by the FTIR, DSC and XRD methods. The release of the cation of p-aminobenzoic acid was per­formed in simulated gastric medium at pH 1.2 and at 37±0.5 °C using UV–Vis analysis to estimate its content. The release data were best fitted to the Higuchi model with high correlation coefficients (r²) and the values of n obtained from the Korsmeyer–Peppas method showed that the drug release followed the Fickian diffusion mechanism.