QPS provides the following in vitro biotransformation study services to support discovery research and development of new drug candidates. Through careful metabolite profiling and identification, we can discover metabolic pathways for new drug candidates.

 ►in vitro metabolic stability in hepatic preparations such as hepatocytes and liver microsomes in animals and humans.
 ►in vitro CYP enzyme inhibition in human liver microsomes.
 ►ex vivo CYP enzyme induction in livers from animal species such as mice, rats, dogs or monkeys after repeated dose treatment in toxicology studies.
 ►Reaction phenotyping using both chemical inhibitor and cDNA expressed enzymes (with reaction velocity linearity study included to determine the incubation time, the protein concentration, and the substrate concentration).

The CYP inhibition potential of new drug candidates can be assessed using a rapid, reliable, and specific method developed by QPS. This method measures the activities of six major human CYP isozymes (CYP1A2, CYP 2B6, CYP 2C9, CYP 2C19, CYP 2D6, and CYP 3A4/5) using selective substrates incubated with human liver microsomes. The method was validated by measuring the inhibition of known CYP inhibitors. The analytical method was validated under GLP guidelines. IC50 values were in good agreement with reported literature values. Other CYP inhibition studies for CYP2A6, CYP2C8, and CYP2E1 are also performed by QPS. Ki determination and pre-incubation to evaluate time-dependent inhibition are sometimes required for some test articles and can be performed by QPS.