Generic equivalence of drugs is a semantically muddled concept. To be meaningful, the criteria for equivalence must be stated. In this simple study, two different formulations of tolbutamide, both generically equivalent in terms of chemical content and specifications of the United States Pharmacopoeia, were found to be clearly not equivalent as measured by availability of drug to the patient (serum drug levels) or therapeutic efficacy (hypoglycemic response). Clarity in pronouncements on this subject should be established so that confusion in terminology and meaning does not lead to "generic inequivalence" of therapeutic response.
Varley AB. The Generic Inequivalence of Drugs. JAMA. 1968;206(8):1745-1748. doi:10.1001/jama.1968.03150080025004