Risk of CYP2C19 Phenoconversion in Healthy Volunteers With Rapid, Normal, and Intermediate Predicted Metabolizers' Status

Plain-language summary

CYP2C19 is responsible for the metabolism of approximately 10% of drugs currently on the market, including several proton pump inhibitors, clopidogrel, benzodiazepines and some tricyclic antidepressants, including amitriptyline. It is a cytochrome whose activity is characterized by a great variability in the general population. This variability can be explained, in part, by genetic and environmental factors The classification of phenotypes associated with CYP2C19 has evolved over time. Today, five distinct phenotypes are used to characterize this variability: the slow metabolizer (SM) phenotype, the intermediate metabolizer (IM) phenotype, the normal metabolizer (NM) phenotype, the fast metabolizer (RM) phenotype and finally the ultra-fast metabolizer (UM) phenotype. (UM) phenotype. Although directly measurable with test substances, CYP2C19 phenotypes are often assigned on the basis of genotype. They may be impacted by intrinsic (e.g., comorbidities) or extrinsic (e.g., co-medications) factors. Phenoconversion or phenotypic change is the phenomenon by which an individual switches from one phenotype to another due to an environmental influence such as a drug interaction. However, genotype is likely to influence the degree of response to a drug interaction. Vulnerability to phenoconversion therefore differs according to the genotype of the individual. The purpose of our study is to determine whether individuals genetically MR, NM and IM have the same vulnerability to phenoconversion. Thus, the magnitude of the response to CYP2C19 inhibition will be studied in these 3 groups of individuals (NM:\*1/\*1, RM:\*1/\*17 and IM:\*1/\*2-\*2/\*17). Inhibition will be studied in two steps, using a strong (fluvoxamine) and a weak (voriconazole) inhibitor of CYP2C19.

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