Twenty-three generic intravenous piperacillin/tazobactam products were compared for in
vitro activity to the branded formulation (Zosyn®, Wyeth, Philadelphia, PA) by disk diffusion
and incremental broth microdilution assay methods. All but 1 lot demonstrated significantly
decreased activity (− 5 to− 35%), necessitating further investigations regarding the chemical
purity, potency, and therapeutic equivalence of these products worldwide. The average−
16% activity across all generic lots was equivalent to underdosing piperacillin/tazobactam …

In vitro potency evaluations of various piperacillin/tazobactam generic products compared
to the contemporary branded (Zosyn®, Wyeth) formulation [Diagnostic Microbiology and
Infectious Disease 61, 76–79, 2008] … In vitro potency evaluations of various piperacillin/tazobactam
generic products compared to the contemporary branded (Zosyn®, Wyeth) formulation [Diagnostic
Microbiology and Infectious Disease 61, 76–79, 2008] …