Current Issues on Bioavailability and Bioequivalence Determination
Chyung S. Cook*
Baxter Healthcare, USA
- *Corresponding Author:
- Chyung S. Cook, Ph.D.
25212 Illinois Route 120
Round Lake, IL 60073, USA
Tel: (847) 270-5319
E-mail: [email protected]
Received Date: August 30, 2011; Accepted Date: September 22, 2011; Published Date: September 24, 2011
Citation: Cook CS (2011) Current Issues on Bioavailability and Bioequivalence Determination. J Bioequiv Availab S1: 003. doi: 10.4172/jbb.S1-003
Copyright: © 2011 Cook CS. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Methodologies for determining bioavailability and bioequivalence of endogenous compounds and macromolecules such as polymers are different from that of small exogenous compounds. In many cases, bioavailability and bioequivalence guidelines for exogenous molecules may not be appropriate for endogenous compounds. A common approach of baseline subtraction for endogenous materials is arguable in some cases, since levels of endogenous materials are highly variable during an experimental period. For polymers molecular weight distribution may be different among the materials from different manufactures and/or different manufacturing processes. These issues are addressed along with following issues regarding bioavailability/ bioequivalence determination: use of pharmacokinetic vs. pharmacodynamic parameters, use of a chiral assay vs. total assay for racemic drugs, and total vs. free concentration assays for drugs that exhibit concentration-dependent plasma protein binding, and for liposome/protein encapsulated formulations.