MECHANISM OF DRUG-RELEASE FROM POLYGLYCEROL ESTER OF FATTY ACID-BASEDMICROSPHERES

The factors influencing the drug release and the mechanism of the drug release from the spherical, polyglycerol ester of fatty acid (PGEF)-b ased microspheres has been elucidated. The release rates of theophylli ne, phenylpropanolamine hydrochloride (PPA) and prednisolone were exam ined. The drug release could be regulated by choosing an appropriate h ydrophile-lipophile balance value of PGEF. The drug solubility in wate r affected the release rate of the drug. The particle size of the micr ospheres did not change during drug release. In addition, the paddle s peed did not affect the release rate. Since the release rate could be expressed by Jander's equation which considers the change in the inter facial area where the actual release of a solid drug occurs, the relea se from the microspheres is found to be a diffusion controlled process within the micromatrix.