Development and Evaluation of Controlled-Release Diltiazem HCl Microparticles Using Cross-Linked Poly(Vinyl Alcohol)

Abstract

Hydrogels of cross-linked poly (vinyl alcohol) (PVA) were developed and their properties were evaluated as a controlled-release oral solid dosage form. The concentration of glutaraldehyde involved in cross-linking is directly proportional to the compactness of the three-dimensional networks of the cross-linked PVA. The theoretical calculations reveal that the release of diltiazem HCl from PVA could be described by the combination of Fickian and diffusion-controlled models. The confirmation of cross-linking was done by differential scanning calorimetry and infrared spectroscopy. The microparticles show lower percentage compressibility but good flowability; hence a capsule dosage form was thought to be suitable. The toxicity level of PVA was confirmed to be 10 g/kg body weight. The microparticle formulation was optimized with respect to size distribution and increased drug loading. The microparticles were physically evaluated with respect to bulk density, angle of repose, and percent compressibility. The microparticles released a drug for 12 hr. The microparticles had a drug loading of 61% to 67%.