Optimization and characterization of controlled release pellets coated with an experimental latex: II. Cationic drug

Abstract

The objective of the present study was to evaluate three process parameters for the application of an experimental latex to obtain multiparticulate controlled drug delivery of prazosin hydrochloride. A laboratory size fluidized bed coating machine (Uniglatt M-2817) was used to coat prazosin hydrochloride (cationic) loaded beads with the experimental latex to release an equivalent of 5 mg of drug in 24 h. A three factor-three level, face-centered cubic design was used to evaluate the effect of inlet air temperature, atomization pressure and spray rate on the cumulative percent released in 24 h with constraints at 6, 12 and 18 h, and the time for the release of 50% of drug ( t 50). Contour and response surface plots were used to relate the independent and dependent variables. The optimization procedure predicted a maximum of 98% release in 24 h when the inlet air temperature, atomization pressure and spray rate were 45.11 °C, 2.5 kp/cm 2 and 11.49 ml/min, respectively. The optimized beads prepared based upon the predicted values, yielded responses which were close to the predicted values. Further, the effect of solids content, coating volume and type of prazosin hydrochloride polymorph on its dissolution from coated beads have been evaluated. All the preparations were characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The release kinetics from the optimized pellets were shown to follow the Higuchi square-root model.