Figure 1. Elution profiles of ropivacaine and its metabolites by high-performance liquid chromatography. (A) Chromatogram of ropivacaine metabolites generated by human hepatic microsomes. Ropivacaine (0.1 mM) was incubated with human hepatic microsomes (200 micro gram of protein) and reduced nicotinamide adenine nucleotide phosphate (0.4 mM) at 37 degrees Celsius for 60 min. (B) Chromatogram of the blank assay. The incubation mixtures were the same as in A except for the omission of reduced nicotinamide adenine nucleotide phosphate.