Generic drugs bioequivalence

W. P. Adams and G. J. P. Singh. Guidance Topical dermatology corticosteroids In vivo bioequivalents, Division of Bioequivalence, Office of Generic Drugs, Food and Drug Administration, 1995. 

Id. at 355(j)(2)(A)(iv). Bioequivalence means that the rate and extent of absorption of the generic drug is not significantly different from the rate and extent of absorption of the listed drug t hen administered at the same dosage. 

The other computation is that of relative bioavailability. This calculation is determined when two products are compared to each other, not to an intravenous standard. This is commonly calculated in the generic drug industry to determine that the generic formulation (e.g., a tablet) is bioequivalent to the original formulation (e.g., another tablet). Thus, bioavailability is not routinely calculated in an individual patient but reserved for product development by a drug manufacturer. However, it is important to have an idea of how formulations or routes of administration differ with respect to bioavailability so as to allow proper dosage adjustment when changing formulations or routes of administration. 

Drug Price Competition and Patent Restoration Act of 1984 Abbreviated new drug applications for generic drugs. Required bioequivalence data. Patent life extended by amount of time drug delayed by FDA review process. Cannot exceed 5 extra years or extend to more than 14 years post-NDA approval. 

For an ANDA, conducting an in vivo study on a strength that is not the highest may be appropriate for reasons of safety, subject to approval by the Division of Bioequivalence, Office of Generic Drugs, and provided that the following conditions are met. 

Generic Drug Product Development Bioequivalence Issues, edited by Isadore Kanfer and Leon Shargel... 

If drugs have the same bioavailability (i.e., the same AUC) they are said to be bioequivalent. This is a particularly important aspect in the development of generic drugs (discussed later). However, it should be appreciated that bioavailability refers ultimately to plasma concentration per se. It does not tell us anything about therapeutic... 

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