[Code of Federal Regulations] [Title 21, Volume 5] [Revised as of April 1, 2004] From the U.S. Government Printing Office via GPO Access [CITE: 21CFR320.28] [Page 194] TITLE 21--FOOD AND DRUGS CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) PART 320_BIOAVAILABILITY AND BIOEQUIVALENCE REQUIREMENTS--Table of Contents Subpart B_Procedures for Determining the Bioavailability or Bioequivalence of Drug Products Sec. 320.28 Correlation of bioavailability with an acute pharmacological effect or clinical evidence. Correlation of in vivo bioavailability data with an acute pharmacological effect or clinical evidence of safety and effectiveness may be required if needed to establish the clinical significance of a special claim, e.g., in the case of a extended release preparation. [42 FR 1648, Jan. 7, 1977, as amended at 67 FR 77674, Dec. 19, 2002]