Comparing generic and innovator drugs: a review of 12 years of bioequivalence data from the United States Food and Drug Administration.
BACKGROUND
In the US, manufacturers seeking approval to market a generic drug product must submit data demonstrating that the generic formulation provides the same rate and extent of absorption as (ie, is bioequivalent to) the innovator drug product. Thus, most orally administered generic drug products in the US are approved based on results of one or more clinical bioequivalence studies.


OBJECTIVE
To evaluate how well the bioequivalence measures of generic drugs approved in the US over a 12-year period compare with those of their corresponding innovator counterparts.


METHODS
This retrospective analysis compared the generic and innovator bioequivalence measures from 2070 single-dose clinical bioequivalence studies of orally administered generic drug products approved by the Food and Drug Administration (FDA) from 1996 to 2007 (12 y). Bioequivalence measures evaluated were drug peak plasma concentration (C(max)) and area under the plasma drug concentration versus time curve (AUC), representing drug rate and extent of absorption, respectively. The generic/innovator C(max) and AUC geometric mean ratios (GMRs) were determined from each of the bioequivalence studies, which used from 12 to 170 subjects. The GMRs from the 2070 studies were averaged. In addition, the distribution of differences between generic means and innovator means was determined for both C(max) and AUC.


RESULTS
The mean +/- SD of the GMRs from the 2070 studies was 1.00 +/- 0.06 for C(max) and 1.00 +/- 0.04 for AUC. The average difference in C(max) and AUC between generic and innovator products was 4.35% and 3.56%, respectively. In addition, in nearly 98% of the bioequivalence studies conducted during this period, the generic product AUC differed from that of the innovator product by less than 10%.


CONCLUSIONS
The criteria used to evaluate generic drug bioequivalence studies support the FDA's objective of approving generic drug formulations that are therapeutically equivalent to their innovator counterparts.
Division of Bioequivalence II, Office of Generic Drugs, Office of Pharmaceutical Sciences, Center for Drug Evaluation and Research, United States Food and Drug Administration, Derwood, MD 20855, USA. barbara.davit@fda.hhs.gov
Barbara M
BM
Davit
Patrick E
PE
Nwakama
Gary J
GJ
Buehler
Dale P
DP
Conner
Sam H
SH
Haidar
Devvrat T
DT
Patel
Yongsheng
Y
Yang
Lawrence X
LX
Yu
Janet
J
Woodcock
D000284:Administration, Oral; D019540:Area Under Curve; D002986:Clinical Trials as Topic; D017277:Drug Approval / Q000331:legislation & jurisprudence*; D016568:Drugs, Generic / Q000191:economics / Q000493:pharmacokinetics*; D006801:Humans; D004364:Pharmaceutical Preparations / Q000008:administration & dosage* / Q000191:economics / Q000378:metabolism; D012189:Retrospective Studies; D013810:Therapeutic Equivalency; D014481:United States; D014486:United States Food and Drug Administration
D016568:Drugs, Generic; D004364:Pharmaceutical Preparations