Decrease in cytochrome P4502E1 as assessed by the rate of chlorzoxazone hydroxylation in alcoholics during the...

Area of Science:

• Pharmacology
• Hepatology
• Toxicology

Background:

• Alcohol abuse is associated with altered drug metabolism.
• Cytochrome P4502E1 (CYP2E1) is a key enzyme involved in ethanol metabolism and is inducible by ethanol.
• Understanding CYP2E1 induction and its resolution is crucial for managing alcohol-dependent individuals.

Purpose of the Study:

• To evaluate the induction of CYP2E1 in alcoholic patients.
• To assess the rate of CYP2E1 activity normalization during alcohol withdrawal.
• To determine if factors like smoking or specific biomarkers correlate with CYP2E1 induction.

Main Methods:

• Chlorzoxazone (CHZ) metabolism was assessed by measuring the ratio of 6-hydroxychlorzoxazone (6-OH-CHZ) to CHZ in blood 2 hours post-ingestion.
• High-performance liquid chromatography (HPLC) was used for quantification.
• The 6-OH-CHZ/CHZ ratio was measured in controls and alcoholic patients at various stages of alcohol withdrawal (1-21 days).

Main Results:

• Alcoholic patients within 2 days of withdrawal showed a significantly higher 6-OH-CHZ/CHZ ratio (1.05 +/- 0.14) compared to controls (0.34 +/- 0.03), indicating CYP2E1 induction.
• The CYP2E1 half-life was determined to be 2.5 days.
• By 8-21 days of abstinence, the ratio in former alcoholics returned to control levels (0.35 +/- 0.03 and 0.31 +/- 0.03, respectively).
• No correlation was found between the ratio and gamma-glutamyltransferase, carbohydrate-deficient transferrin, or daily alcohol consumption.
• Smoking did not influence CHZ hydroxylation rates.

Conclusions:

• The 6-OH-CHZ/CHZ ratio is a reliable marker for assessing hepatic and extrahepatic CYP2E1 activity in humans.
• CYP2E1 induction in alcoholics is substantial but transient, resolving relatively quickly after cessation of alcohol intake.
• This marker can be valuable in clinical settings for monitoring alcohol withdrawal and its metabolic consequences.