Cytochrome P450 3A (CYP3A) and Cytochrome P450 2C9 (CYP2C9) (CYP3A/CYP2C9)

Cytochrome P450 3A (CYP3A) and Cytochrome P450 2C9 (CYP2C9) are major phase I drug-metabolizing enzymes belonging to the cytochrome P450 superfamily (Source: UniProt P08684, P11712). These enzymes are primarily expressed in the liver and intestines, where they catalyze the oxidation of various endogenous and exogenous compounds (Source: NIH StatPearls). In clinical pharmacology, they are the primary enzymes responsible for the metabolic clearance of avatrombopag, a small-molecule thrombopoietin receptor agonist used to treat thrombocytopenia (Source: FDA Doptelet Label). Avatrombopag undergoes oxidative metabolism, with CYP3A4 and CYP2C9 serving as the principal mediators of its systemic elimination (Source: PubMed PMID: 29774143). Because these enzymes are susceptible to induction and inhibition by other medications, they represent a significant source of drug-drug interactions that can alter avatrombopag plasma concentrations (Source: PharmGKB). Furthermore, genetic polymorphisms in the CYP2C9 gene can lead to inter-individual variability in drug exposure, potentially impacting the clinical response and safety profile of the treatment (Source: PubMed PMID: 30105554). Understanding the role of these enzymes is crucial for optimizing dosing regimens and ensuring patient safety during avatrombopag therapy.

Other names

CYP3ACYP2C9Cytochrome P450 family 3 subfamily ACytochrome P450 family 2 subfamily C member 9CYP3A4CYP3A5

These enzymes facilitate the metabolic clearance of avatrombopag through oxidative pathways, primarily 4-hydroxylation, thereby regulating its systemic exposure and duration of action.