Sustained-release dosage form of phenylpropanolamine hydrochloride. Part I: Microencapsulation and in vitro release kinetics.

Microcapsules of phenylpropanolamine hydrochloride with core:wall ratios of 1:1, 2:1 and 1:2 were prepared by the coacervation-phase separation method, using ethylcellulose as the coating material. Two batches of PPA.HCl powder with different particle sizes (> 58 microns and < 28 microns) were used as the core material. The different sizes of microcapsules were separated using a range of standard sieves (840-247 microns). The effects of drug particle size, the media pH and the core:wall ratio on the dissolution kinetics were studied, and evaluated kinetically.