RESUMEN
The present work deals with various attempts to prepare a gastroretentive formulation of lacidipine for treating gastroparesis. High density sucrose beads were modified by coating with certain polymers, but unfortunately sustained release could not be achieved. Granules were prepared by wet granulation technology using different combinations of polymers and a release of the drug was observed. The method failed to release the drug as per desired specifications. Polymeric coating followed by wet granulation was thought to be a better process to sustain the dissolution rate. The release rate can be modified by the incorporation of different polymeric coatings, but the mucoadhesive potential of granules was only 4.23% which might be due to its large size and the presence of other ingredients. Further, the lacidipine loaded microparticles were prepared by different methods such as compression, ionic gelation with TPP, ionic gelation with TPP and glutaraldehyde, spray drying and coacervation techniques. The formulations were evaluated for average particle size, surface morphology, entrapment efficiency, % yield and mucoadhesive potential. The microparticles prepared by compression method using HPMC K4M and SCMC as mucoadhesive polymers and BaSO4 as high density diluent showed poor bioadhesion (8.3%) and poor release characteristics (100% in 120 min). Ionic gelation with tripolyphosphate yielded microspheres with poor mechanical strength. In order to improve its mechanical strength, TPP ionic gelation was combined with step-wise cross-linking with glutaraldehyde. The additional solidification step to improve mechanical strength left this procedure tedious, time consuming and cytotoxic. Spray drying method gave a very low yield with 46.67% bioadhesion. The method using CaCl2 for ionotropic gelation showed the best results with regard to physical characteristics (well formed discrete, spherical surface microcapsule), particle size (88.57 ± 0.51), in vitro bioadhesion (67.33%), yield (>85%) and loading (>70%).