In the current study, p-aminobenzoic acid-loaded ethylcellulose microspheres were prepared under various conditions by solvent evaporation method (o/w). This preparation was carried out with different p-aminobenzoic acid:ethylcellulose (PABA:EC) ratios, stirring speed, surfactant nature and concentration in order to investigate their effect on encapsulation efficiency and drug release kinetics. Scanning Electron Microscopy (SEM) studies showed spherical microspheres with a porous surface and different structures. The mean diameter of Sauter (d32) of these microparticles is in the range from 47 to 165 ?m with PVA and from 793 to 870 ?m 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 pro-longed release. Microspheres were characterized by FTIR, DSC and XRD. The release of cation of p-aminobenzoic acid was performed in simulated gastric medium at pH 1.2 and 37?0.5?C by UV-VIS analysis to estimate its content. The release data were best fitted to Higuchi model with high correlation coefficient (r?) and the obtained values of n from Korsmeyer-Peppas showed that the drug release follows the Fickian diffusion mechanism.

Four secondary amides have been prepared by the Schotten-Baumann reaction between model anilines (Pa1-4: p-XC6H4NH2: X1: H; X2:CH3; X3:COCH3; X4: CN) and methacryloyl chloride using aqueous THF/NaOH mixture at 0°C. MS1, MS2 and MS4 liquid monomers are obtained whereas MS3 is a solid monomer. Mass radical copolymerization of the different monomers (MS1-4) with N-vinyl-2-pyrrolidone yields to the corresponding four copolymers. All the monomers have been characterized by IR, 1H and 13C NMR. The (CP1-4) have been characterized by IR spectra, microanalysis, Tg ° and Mv. The kinetics of aniline delivery to give anilinium cations (PaH+)1-4 from solid MS3 and CP1-4 dispersed in water (pH= 1.2, 37°C) showed that aniline delivery from the different supports is controlled by a diffusion process and not the rate of amide hydrolysis. The amount (%) of free anilinium cations is inversely proportional to the molecular weight of polymeric supports. Accordingly, the monomer MS3 gave the largest amount of free anilinium cations (PaH+) 1-4

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