Fabrication and comparative bioavailability of modified gum microspheres loaded with disopyramide phosphate

The present study aims to develop a controlled rele ase formulation of Disopyramide Phosphate (DSP) loa ded into natural and modified gum microspheres, using waterin-oil emulsification solvent evaporation technique tilizing wetting agent. Effect of different process variable s such as drug and gums ratio (1:1: 0.75 % w/v), st irring speed and time ( 1800 rpm & 210 min ), addition of surfac tant (0.5 % w/v), effect of oily phase ( 200 ml), t emperature of the emulsified phase (80 0 C), effect of cross-linker (0.5 % w/v) and effect of encapsulating agent (1.2 % w/v) on drug loading during the preparation of microspheres were optimized to produce microspheres. Sieve anal ysis data indicated that the prepared microspheres were in th e range of 106 to500 μm. Prepared microspheres were spherical in shape as shown by SEM photomicrographs. Encapsul ted drug in the prepared formulations was stable a s confirmed by FTIR & DSC studies. A single dose rand omized two period cross over study was conducted to compare the pharmacokinetics and bioavailability of test formulation DXML1 (product B –150 mg of DP lo aded in MLBG) with standard formulation (Product A Norp ace CR150 mg capsule). The observed mean values T max, Cmax, AUC0 -∞, Ka, t 1/2 and Kel for products A & B does not show any significant st ati ical difference. From the dissolution point and in vivo bio availability for products A & B could be considered bio equivalent. The drug release performance was greatly affected by the mat erials used in the microsphere preparation which al lows maximum absorption in the intestine.