Inhibition of carboxylesterase-1 alters clopidogrel metabolism and disposition

Area of Science:

• Pharmacology
• Drug Metabolism
• Biochemistry

Background:

• Clopidogrel is a crucial antiplatelet medication for cardiovascular disease patients.
• Research often overlooks human carboxylesterase-1 (CES1) in clopidogrel metabolism, despite its significant role (85-90%).
• Hepatic CYP450 metabolism is traditionally emphasized, yet CES1 is the primary enzyme for clopidogrel hydrolysis.

Purpose of the Study:

• To investigate the impact of alcohol, a known CES1 inhibitor, on clopidogrel metabolism.
• To evaluate alcohol's effects both in vitro using human liver fractions and in vivo using a CES1-deficient mouse model.
• To understand how altered CES1 activity influences clopidogrel's metabolic profile and active metabolite formation.

Main Methods:

• In vitro studies utilized human recombinant CES1 and human liver S9 (HLS9) fractions to assess alcohol's inhibitory effects on clopidogrel hydrolysis.
• In vivo studies employed a plasma carboxylesterase deficient mouse (Es1) strain, administering clopidogrel with and without alcohol.
• Metabolite concentrations, including the active H4 metabolite, and area under the curve (AUC) were quantified to determine metabolic changes.

Main Results:

• Alcohol demonstrated significant inhibition of clopidogrel hydrolysis (IC50 161 mM) and 2-oxo-clopidogrel formation (IC50 6 mM).
• In HLS9 fractions, alcohol induced ethylated metabolites and increased the formation of the active H4 metabolite.
• In Es1 mice, alcohol administration led to a 91% increase in clopidogrel AUC, a 22% increase in H4 AUC, and reduced carboxylate metabolite formation by 48% and 42% respectively.

Conclusions:

• Clopidogrel metabolism is highly sensitive to variations in CES1 activity.
• Alcohol's inhibition of CES1 significantly alters clopidogrel's metabolic pathway, increasing active metabolite exposure.
• The Es1 mouse model effectively mimics human CES1 drug metabolism, providing a valuable tool for assessing CES1 function impacts on drug disposition.