[Code of Federal Regulations]
[Title 21, Volume 5]
[Revised as of April 1, 2001]
From the U.S. Government Printing Office via GPO Access
[CITE: 21CFR320.1]

[Page 186-187]
 
                        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 A--General Provisions
 
Sec. 320.1  Definitions.


    (a) Bioavailability means the rate and extent to which the active 
ingredient or active moiety is absorbed from a drug product and becomes 
available at the site of action. For drug products that are not intended 
to be absorbed into the bloodstream, bioavailability may be assessed by 
measurements intended to reflect the rate and extent to which the active 
ingredient or active moiety becomes available at the site of action.
    (b) Drug product means a finished dosage form, e.g., tablet, 
capsule, or solution, that contains the active drug ingredient, 
generally, but not necessarily, in association with inactive 
ingredients.
    (c) Pharmaceutical equivalents means drug products that contain 
identical amounts of the identical active drug ingredient, i.e., the 
same sat or ester of the same therapeutic moiety, in identical dosage 
forms, but not necessarily containing the same inactive ingredients, and 
that meet the identical compendial or other applicable standard of 
identity, strength, quality, and purity, including potency and, where 
applicable, content uniformity, disintegration times and/or dissolution 
rates.
    (d) Pharmaceutical alternatives means drug products that contain the 
identical therapeutic moiety, or its precursor, but not necessarily in 
the same amount or dosage form or as the same salt or ester. Each such 
drug product individually meets either the identical or its own 
respective compendial or other applicable standard of identity, 
strength, quality, and purity, including potency and, where applicable, 
content uniformity, disintegration times and/or dissolution rates.
    (e) Bioequivalence means the absence of a significant difference in 
the rate and extent to which the active ingredient or active moiety in 
pharmaceutical equivalents or pharmaceutical alternatives becomes 
available at the site of drug action when administered at the same molar 
dose under similar conditions in an appropriately designed study. Where 
there is an intentional difference in rate (e.g., in certain controlled 
release dosage forms), certain pharmaceutical equivalents or 
alternatives may be considered bioequivalent if there is no significant 
difference in the extent to which the active ingredient or moiety from 
each product becomes available at the site of drug action. This applies 
only if the difference in the rate at which the active ingredient or 
moiety becomes available at the site of drug action is intentional

[[Page 187]]

and is reflected in the proposed labeling, is not essential to the 
attainment of effective body drug concentrations on chronic use, and is 
considered medically insignificant for the drug.
    (f) Bioequivalence requirement means a requirement imposed by the 
Food and Drug Administration for in vitro and/or in vivo testing of 
specified drug products which must be satisfied as a condition of 
marketing.

[42 FR 1634, Jan. 7, 1977, as amended at 42 FR 1648, Jan. 7, 1977; 57 FR 
17997, Apr. 28, 1992]