ABSTRACT
HO-WAH HUI* and JOSEPH R. ROBINSON / Universi ty of Wisconsin, Madison, Wisconsin
VINCENT H. L. LEE / Universi ty of Southern California, Los Angeles , California
I . In t roduct ion 373
II . Design and Fabrication of Oral Systems 375
A. Dissolution Controlled Release 376 B . Diffusion Controlled Release 391 C . Diffusion and Dissolution Controlled Release 405 D. Ion-Exchange Resins 412 E. pH-Independent Formulations 413 F . Osmotically Controlled Release 414 G. Altered Density Formulations 418
III . Summary 420
References 421
I. INTRODUCTION
Oral ingest ion has long been the most convenient and commonly employed route of d r u g de l ivery . Indeed , for sus ta ined-re lease s y s - tems , the oral route of administration has by far received the most a t tent ion with respec t to r e sea rch on physiological and d r u g cons t ra in t s
^Current affiliation: Abbott Labora tor ies , North Chicago, Illinois
as well as design and testing of products. This is because there is more flexibility in dosage form design for the oral route than there is for the parenteral route.
