In vitro drug interaction studies of atorvastatin with ciprofloxacin, gatifloxacin, and ofloxacin

We describe the in vitro availability of atorvastatin, a potent HMG-CoA reductase inhibitor, in presence of ciprofloxacin, gatifloxacin, and ofloxacin, all with a wide antibacterial spectrum. These studies were performed at 37°C, 48°C, and 60°C in different pH environments, simulating human body compartments. The reactions were studied by UV spectroscopy, and the availability of both the drugs in presence of each other was determined by deriving a simultaneous equation for two component system through modification of Beer’s law. It has been observed that due to interaction, the availability of both atorvastatin and quinolones increased considerably in nearly all pH mediums, which are attributed to the formation of charge-transfer complexes. The results were further confirmed by IR, HNMR, and mass spectrometric studies.