Controlled Release of Verapamil Hydrochloride , an Antihypertensive Drug from the Interpenetrating Blend Microparticles of Gelatin and Gellan Gum

Carbohydrate polymers are extensively used in the recent years in biomedical and pharmaceutical applications due to their biocompatibility and biodegradability. Among such natural polymers, gelatin (GL) and gellan gum (GG) have been chosen in the present work because of their pharmaceutical applications. This work reports on the development of novel interpenetrating polymer network (IPN) microparticles of GL and GG using maleic anhydride as crosslinker. Verapamil hydrochloride, an antihypertensive drug, was successfully encapsulated into these IPN microparticles. Various formulations of microparticles were prepared by varying the ratio of GL and GG and % of drug loading. These microparticles were characterized by Fourier transform infrared spectroscopy to understand the formation of IPN structure and to confirm the possible chemical interactions between drug, polymer, and cross-linking agent. Scanning electron microscopy was used to study the surface morphology of the microparticles which showed slight rough surfaces. Differential scanning calorimetry and X-ray diffraction studies were performed to understand the crystalline nature of the drug after encapsulation into IPN microparticles and distribution of the drug into the microparticles. Drug encapsulation of up to 90% was achieved as measured by the ultraviolet method. Both equilibrium and dynamic swelling experiments were performed in water. In vitro release studies indicated a dependence of release rate on both the extent of crosslinking and the amount of GL used to produce microparticles, but the slow release was extended up to 25 h. Cumulative release data were fitted to an empirical equation to compute diffusional exponent (n), which indicated non-Fickian trend for drug release. The studies of IPN microparticle system could be useful drug carrier for the encapsulation of fragile drugs and provide new opportunities in the field of bioencapsulation.