With globalization of the pharmaceutical industry, newly approved drugs nearly always become available worldwide, including the 3 major pharmaceutical regions: the United States, Europe, and Japan. One might think that these drugs would have the same recommended dosing throughout the world, but this appears not to be true in many instances. The objective of this study was to identify any patterns of differences in labeled dosing. Approved labeling, for the most widely prescribed proprietary drugs in the United States, was used as a basis for this study. Dosing was compared, for common indications, for the United States, Europe, and Japan. Overall, these data indicate that there are numerous differences in approved dosing for drugs approved in all 3 regions. For about half of the drugs studied, dosing in Japan is considerably lower than the United States or Europe. Some differences in dosing are also apparent between the United States and Europe.

Bioavailability and/or bioequivalence studies play a key role in the drug development period for both new drug products and their generic equivalents. For both, these studies are also important in the postapproval period in the presence of certain manufacturing changes. Like many regulatory studies, the assessment of bioavailability and bioequivalence can generally be achieved by considering the following three questions. What is the primary question of the study? What are the tests that can be used to address the question? What degree of confidence is needed for the test outcome? This article reviews the regulatory science of bioavailability and bioequivalence and provides FDA's recommendations for drug sponsors who intend to establish bioavailability and/or demonstrate bioequivalence for their pharmaceutical products during the developmental process or after approval.

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