Impact on Bacterial Resistance of Therapeutically Nonequivalent Generics: The Case of Piperacillin-Tazobactam
Fig 4
LC/MS analysis of innovator (Wyeth) and generic (Farmalogica) TZP.
LC/MS analysis of TZP of innovator (Wyeth, panels A, B and C) and generic (Farmalogica, panels D, E and F) TZP from mouse serum 2 hours after the 640 mg/kg dose. Panels A and D correspond to the complete spectrogram along a 13-minute run, Panels B and E to the specific spectrogram of tazobactam (299:300 Da) and Panels C and F to the specific spectrogram of piperacillin (518:519 Da). The spectrum of the tazobactam component differed markedly between Farmalogica (Panel E) and Wyeth (Panel B). In the generic, the tazobactam peak appears unstable because there are compounds with the same molecular mass but different retention times, while in the innovator the tazobactam peak is neatly defined. It suggests product isomer heterogeneity in the tazobactam component of the Farmalogica product.