Functional characteristics of CYP3A4 allelic variants on the metabolism of loperamide in vitro.

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Lin QM, Li YH, Liu Q, Pang NH, Xu RA, Cai JP, Hu GX

Functional characteristics of CYP3A4 allelic variants on the metabolism of loperamide in vitro.

Infect Drug Resist. 2019 Sep 10;12:2809-2817. doi: 10.2147/IDR.S215129. eCollection 2019.

PubMed ID
31571937 [ View in PubMed
]
Abstract

BACKGROUND: Cytochrome P450 3A4 (CYP3A4) appears to be genetically polymorphic, which in turn contributes to interindividual variability in response to therapeutic drugs. Loperamide, identified as a CYP3A4 substrate, is prone to misuse and abuse and has high risks of life-threatening cardiotoxicity. METHODS: Thus, this study is designed to evaluate the enzymatic characteristics of 29 CYP3A4 alleles toward loperamide in vitro, including the 7 novel CYP3A4 variants (*28-*34). The incubation system (containing CYP3A4 enzyme, cytochrome b5, 0.5-20 muM loperamide, potassium phosphate buffer and nicotinamide adenine dinucleotide phosphate) was subject to 40-mins incubation at 37 degrees C and the concentrations of N-demethylated loperamide were quantified by UPLC-MS/MS. RESULTS: As a result, CYP3A4.6, .17, .20 and .30 showed extremely low activity or no activity and the rest of CYP3A4 variants presented varying degrees of decrements in catalytical activities when compared with CYP3A4.1. CONCLUSION: As the first study to identify the properties of these CYP3A4 variants toward loperamide metabolism, our investigation may establish the genotype-phenotype relationship for loperamide, predict an individual's capability in response to loperamide, and provide some guidance of clinical medication and treatment for loperamide.

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