T. Kristmundsdottir et al., RELEASE OF DILTIAZEM FROM EUDRAGIT MICROPARTICLES PREPARED BY SPRAY-DRYING, International journal of pharmaceutics, 137(2), 1996, pp. 159-165
Microparticles containing diltiazem hydrochloride were prepared by the
spray-drying technique using acrylate-methacrylate copolymers, Eudrag
it RS and Eudragit RL, as coating materials. The choice of solvent use
d during spray-drying determined the structure of the resultant microp
articles. Spray-drying using dichloromethane as the solvent resulted i
n microspheres where the drug was distributed in the coating polymer m
atrix, whereas using toluene gave microcapsules with the drug coated b
y the polymer. The particle size distribution for both microspheres an
d microcapsules was narrow, with mean particle size below 10 mu m. DTA
-analysis showed that the drug was amorphous in the microspheres but c
rystalline in the microcapsules. The release pattern of diltiazem hydr
ochloride was affected by microparticle structure, whether the structu
re was matrix (microspheres) or reservoir (microcapsules). The results
indicate that spray-drying is a method that can be used to prepare mi
croparticles from the Eudragit acrylic resins RL and RS with a narrow
particle size distribution. It is concluded that drug release rate can
be controlled by choice of polymer type and production conditions dur
ing spray-drying.