CYP Inhibition Assays

 

CYP Inhibition Assays

CYP inhibition studies are an essential part of drug discovery to evaluate and predict in vivo drug-drug interactions.

Inhibition of cytochrome P450 catalytic activity is a leading mechanism of metabolism-based drug-drug interactions. Many DDI-related pre-clinical/clinical failures to date have been attributed to CYP-related hepatic metabolism. Hence it has become essential to screen compounds in early drug discovery to monitor their in vitro inhibition of the major CYP isoforms and predict their in vivo effects.

Catalytic activities of various CYP isoforms are measured by incubating isoform-specific drug substrates in human liver microsomes in the presence of NADPH. All QDI CYP inhibition assays utilize drug substrates and monitor specific drug metabolites that are recommended by the FDA and EMA.

CYP Inhibition: Standard Assay Conditions (Customizable)

CYP Isoforms
CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 (other isoforms, such as CYP2E1, are available)

Matrix
Pooled Whole Human Liver Microsomes

CYP Substrates
CYP1A2-Phenacetin
CYP1A2-Tacrine (only for RapidFire-MS/MS)
CYP2B6-Bupropion
CYP2C8-Paclitaxel
CYP2C9-Tolbutamide
CYP2C19-Mephenytoin
CYP2D6-Bufuralol
CYP2E1-Chlorzoxazone
CYP3A4-Testosterone
CYP3A4-Midazolam

Testing Compound Concentration
0, 0.2, 0.5, 1.3, 3.2, 8, 20, 50 μM

Detection Method
Specific metabolites by LC-MS/MS or RapidFire-MS/MS

Deliverables
IC50, Standard error of IC50, Report

Turnaround Time
2-3 Days

Compound requirements
100 μL 50 mM DMSO stock or 1-2 mg solid