Development and evaluation of Nefopam hydrochloride microcapsules

An attempt was performed to encapsulate Nefopam hydrochloride, a highly water soluble drug, by a modified emulsion solvent evaporation/extraction technique, using cellulose acetate butyrate (CAB) as a coating polymer. The influence of core/coat ratio (1:2, 1:1 and 2:1 ratio) on the yield, drug loading, size distribution as well as the release characteristics and surface topography of the prepared microcapsules was investigated The obtained microcapsules exhibited higher encapsulation efficiency and a decreased release rate in simulated gastric fluid (S. G. F pH 1.2) and simulated intestinal fluid (S.I.F. pH 7.4). On the other hand, the entrapment efficiencies increased (from 104.66 to 141.26, core coal ratio 1: 1) and the release rate decreased with increasing microcapsule size (from 250 to 512.5 mu m) and/or theoretical drug loading of microcapsules. Kinetic assessment of the release rate of microcapsules using different mathematical models has shown that the release rate followed Ritger-Peppas diffusion release kinetics.