Development and characterization of mixed gels based hydrogel, emulgel and bigel.

The present study was based on development of gel formulations of agar-gelatin hydrogels, emulgels and bigels which were evaluated as delivery modules for metronidazole (MTZ). Agar and gelatin were used for the preparation of mixed food hydrogels. Soyabean oil (SO) was used for the preparation of emulgels and was incorporated within the prepared hydrogel. Organogel was prepared using soyabean oil as a solvent and stearic acid (SA) as organogelator. The bigel was prepared by mixing organogels with the agar-gelatin hydrogel. The prepared gels were characterized for their surface morphology, mechanical properties, chemical interactions and electrical properties. Field emission scanning electron microscopy was used to visualize the surface topography. XRD studies established the amorphous nature of the gels. FTIR study confirmed the interpolymeric bonding between gelatin and agar as well as encapsulation of soyabean oil within the polymeric matrix. There was no interaction between the polymers and drug. The hydrogels showed lower impedance than emulgels and bigels indicating higher content of aqueous phase within it. The hemocompatibility test confirmed the blood compatibility of the preparations. The emulgel showed least mucoadhesive characteristic while the hydrogel sample showed highest mucoadhesion. The leaching study confirmed the presence of oils in the samples. The swelling profiles for the formulations were in tune with in vitro release studies at pH 7.2 phosphate buffer. Metronidazole was used as a model antimicrobial drug to incorporate within the preparations. The antimicrobial efficiency of all the drug loaded formulations was found to be equivalent.