OPTIMIZATION AND CHARACTERIZATION OF CONTROLLED-RELEASE PELLETS COATED WITH AN EXPERIMENTAL LATEX .1. ANIONIC DRUG

The aim of the present study was to evaluate the suitability of an experimental latex as a controlled release coating dispersion by preparing, optimizing and characterizing pellets of ibuprofen. A laboratory size fluidized bed coating machine (Uniglatt M-2817) was used to coat ibuprofen loaded beads with the experimental latex to release 400 mg of ibuprofen in a 12 h period in pH 7.2 phosphate buffer. Independent variables such as solids content, volume of coating dispersion, and plasticizer concentration were optimized using a three-factor, three-level Box-Behnken design. The response studied was cumulative percentage dissolved in 12 h with constraints on 1, 6 and 12 h. Surface response plots were utilized to relate the dependent and the independent variables. The optimization procedure generated a maximum of 86% release in 12 h when the levels of solids content, volume of coating dispersion and plasticizer concentration were 11.06% w/w, 113.7 mi, and 26.59% w/w respectively. The optimized pellets prepared based on the predicted levels yielded response values which were close to the predicted values. The kinetics of release was shown to follow Baker-Lonsdale model. The formulations were characterized using DSC, SEM and X-ray diffraction studies. Comparative evaluation with other commercial preparations indicated that the experimental latex provides a more efficient release of the anionic drug, ibuprofen.