Preparation, Characterization, and Diltiazem HCl Release Study of Chitosan / poly(vinyl alcohol) Microspheres

Abstract

The aim of this study was to develop a procedure for prepared ,and
characterization a controlled-release microspheres polymers like chitosan , polyvinyl
alcohol (PVA) containing Diltiazem HCl (DTZ), as a model drug, was obtained using
a modified emulsification/solvent-evaporation method, induced by addition of
glutaraldehyde (GA) as a crosslinking agent. The microspheres were characterized by
Fourier transform infrared spectroscopy, differential scanning calorimetry (DSC), and
photomicrographs microscopy. The effect of different process parameters, such as
drug/polymer ratio and stirring rate during preparation of microspheres, on the
morphology, size distribution, and in vitro drug release of microspheres was studied.
As expected, stirring rate influenced particle size distribution of microspheres and
hence drug release profiles. By increasing the stirring speed from 400 to 1200 rpm,
the mean diameter of microspheres decreased from 350 μm to 104 μm. The drug
release rate from smaller microspheres was faster than from larger microspheres.
Increasing the drug content of microspheres from 20% to 40% w/w led to
significantly faster drug release from microspheres. It was also studied the release of
(DTZ) at different pH values (1.2, and 7.4) at 37°C. The results indicated that drug
release was much higher at pH 1.2 than that of at pH 7.4.