Evaluation of a floating dosage form of nicardipine hydrochloride and hydroxypropylmethylcellulose acetate succinate prepared using a twin-screw extruder

A floating dosage form composed of nicardipine hydrochloride (NH) and hydro xypropylmethylcellulose acetate succinate (enteric polymer) was prepared us ing a twin-screw extruder. By adjusting the position of the high-pressure s crew elements in the immediate vicinity of die outlet, and by controlling t he barrel temperature, we were able to prepare a puffed dosage form with ve ry small and uniform pores. It was found that the porosity and pore diamete r could be controlled by the varying amount of calcium phosphate dihydrate. In the shaking lest. the puffed dosage form was found to have excellent fl oating ability and mechanical strength in acid solution (JP First Fluid, pH 1.2). The dissolution profile of NH was controlled by the amount of wheat starch. In the dissolution test using JP Second Fluid (pH 6.8), rapid disso lution of NH and loss of buoyancy were observed. It was shown that the puff ed dosage form, consisting of enteric polymer prepared using the twin-screw extruder, was very useful as a floating dosage form that was retained for a long period in the stomach. (C) 2001 Elsevier Science B.V. All rights res erved.