Michaelis-Menten elimination kinetics of acetaldehyde during ethanol oxidation.

Abstract

BACKGROUND:

Acetaldehyde (AcH) is a toxic metabolite of ethanol (EtOH). The pharmacokinetics of blood AcH during EtOH oxidation was studied with or without the administration of aldehyde dehydrogenase 2 inhibitor (cyanamide) in rabbits.

METHODS:

An bolus of EtOH saline solution (0.25, 0.5, 1.0, 1.5, and 2.0 g/kg) was injected intravenously. Cyanamide was administered intraperitoneally (25 mg/kg body weight) to the cyanamide-treated group. Blood EtOH and AcH concentrations were measured by using head-space gas chromatography.

RESULTS:

In the control group, the first peak of the blood AcH appeared immediately and the second elevation appeared 1 to 4 hr after administration at a high EtOH dose. The blood AcH levels other than the second elevation part were significantly correlated to the blood EtOH levels. In the cyanamide-treated group, a peak and a plateau formed at the time corresponding to the second peak in the control group. The peak and plateau concentration of AcH increased markedly. We attempted simultaneous curve fitting, using the five blood EtOH and AcH concentration-time curves, to determine the pharmacokinetic model. Consequently, the AcH elimination was best described by a Michaelis-Menten kinetic model in both groups.

CONCLUSIONS:

The blood AcH profile was suggested to consist of the first and second components that are related to the blood EtOH concentration itself and the metabolic formation of AcH, respectively. With higher EtOH doses or aldehyde dehydrogenase 2 inhibition, the second component becomes prominent as a result of the capacity-limited property of the metabolism of AcH, which is described by Michaelis-Menten elimination kinetics.

• Authors: Tatsuya Fujimiya, Kiyoshi Yamaoka, Yumiko Ohbora, Toshihiko Aki, Hiromi Shinagawa
• Journal: Alcoholism, clinical and experimental research (Alcohol Clin Exp Res) Vol. 26 Issue 8 Suppl Pg. 49S-54S (Aug 2002) ISSN: 0145-6008 [Print] England
• PMID: 12198375 (Publication Type: Journal Article)

Chemical References

• Ethanol
• Cyanamide
• ALDH2 protein, human
• Aldehyde Dehydrogenase
• Aldehyde Dehydrogenase, Mitochondrial
• Acetaldehyde

Topics

• Acetaldehyde (pharmacokinetics)
• Aldehyde Dehydrogenase (antagonists & inhibitors, physiology)
• Aldehyde Dehydrogenase, Mitochondrial
• Animals
• Cyanamide (pharmacology)
• Ethanol (pharmacokinetics)
• Metabolic Clearance Rate (physiology)
• Oxidation-Reduction
• Rabbits