Novel controlled release of antihypertensive drug: preparation, in-vitro and in-vivo evaluation

The objective was to control the release of diltiazem HCl. Emulsion solvent evaporation technique was applied to encapsulate diltiazem HCl using ethyl cellulose or Eudragit RS100. The prepared microspheres were characterized concerning entrapment efficiency; micromeritics properties and surface morphology using SEM and mixed with carbopol, hydroxypropyl methyl cellulose, or chitosan in different ratios. The in-vitro dissolution and kinetic analysis were carried out using various models. In-vivo studies for selected formulae were carried out compared with a marketed product to evaluate their pharmacokinetic parameters. The prepared microspheres showed entrapment efficiency of 67.45 and 76.82% for ethyl cellulose and Eudragit microspheres, respectively. Moreover, Eudragit microspheres mixed with hydroxypropyl methyl cellulose at a ratio of 1:3 showed a sustained release of diltiazem HCl over 12 h, with t½ 14.8 hr. The formulated diltiazem HCl capsule can be successfully used for twice daily dosing.