Quintara Discovery

CYP450 Inhibition Assays

CYP450 inhibition studies are an essential part of drug discovery to predict in vivo drug-drug interactions.

Inhibition of cytochrome P450 enzyme 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 CYP450-related hepatic metabolism. Hence it becomes essential to screen compounds in early drug discovery to monitor their in vitro inhibition of the major CYP450 isoforms in order to predict their in vivo effects.

Despite the many CYP450 isozymes present in man, five major isoforms (3A4, 2C9, 2C19, 2D6, 1A2) account for the metabolism-related DDI issues for greater than 90% of marketed drugs.

Commonly such assays probe the metabolism-related DDI of drug candidates by monitoring the effect of the test compounds on CYP450 metabolic activity using a known substrate. The FDA and EMA recommend many specific drug substrates for CYP450 isoforms.

CYP450 Inhibition: Standard Assay Conditions (Customizable)

CYP Isoforms CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6 and CYP3A4 (other isoforms are available)
Matrix Pooled Whole Human Liver Microsomes
CYP450 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