Bioequivalence:  Scientific basis on which generic and brand-name drugs are compared. To be considered bioequivalent, the bioavailability of two products must not differ significantly when the two products are given in studies at the same dosage under similar conditions. Some drugs, however, are intended to have a different absorption rate. FDA may consider a product bioequivalent to a second product with a different rate of absorption if the difference is noted in the labeling and doesn't affect the drug's safety or effectiveness or change the drug's effects in any medically significant way.