Development of a modified-release pellets formulation--with metoprolol tartrat and kinetic aspects of in vitro release.

AIM The development of a new pellets formulation which is able to modulate the release of metoprolol tartrate, an active pharmaceutical ingredient very soluble in water and therefore very difficult to process. MATERIALS AND METHODS Two types of different viscosity grade hydroxypropyl methylcellulose (Methocel K100; HPMC 15.000) and Eudragit NE30D are used as prolonged drug release agents, thus resulting in three formulations which have been prepared in form of pellets, in a conventional coating pan. The obtained pellets are characterized and compared in terms of: particles size distribution, drug loading efficiency, drug content and kinetic of in vitro drug release. RESULTS Lower amounts of Eudragit NE30D (7.5%) determine more uniform size distributions of particles. Drug content and charging efficiency is higher in case of fractions ranging in size from 0.80 to 1.25 mm. The combination of HPMC 15000 with 10% Eudragit NE30D leads to a prolongation for a period of 11.5 hours of metoprolol tartrate release. Release kinetics analysis was performed by fitting the in vitro release profile with different kinetic models. CONCLUSIONS It was developed a pellets formulation that release in vitro the metoprolol tartrate in an extended mode, with Korsmeyer-Peppas kinetic-type.