Related Experiment Video
Updated: May 30, 2026

Functional Characterization of Carboxylesterases in Insecticide Resistant House Flies, Musca Domestica
Published on: August 23, 2018
Species difference in the inhibition of pentobarbital metabolism by empenthrin
1Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd., 3-1-98, Kasugade-naka, Konohana-ku, Osaka 554, Japan.
Abstract:
Empenthrin, synthetic pyrethroid, prolonged the pentobarbital-induced sleeping time in mice, but not in rats, guinea pigs or hamsters. Empenthrin did not delay the clearance of pentobarbital from serum in dogs. In addition, empenthrin dose-dependently inhibited in vitro metabolism of pentobarbital in mice, but not in rats, guinea pigs, hamsters or rabbits. Lineweaver-Burk plots indicated that the inhibition was competitive in mice. Microsomal fractions of recombinant yeast expressing human cytochrome P-450 (CYP)s were used to determine the inhibitory effect of empenthrin on pentobarbital metabolism in humans. CYP2B6 and CYP2D6 were responsible for biotransformation of pentobarbital to a pentobarbital alcohol identified as 5-ethyl-5-(1'-methyl-3'-hydroxybutyl) barbituric acid. The structure of pentobarbital fit the criteria for a CYP2D6 substrate on computational analysis. Empenthrin did not inhibit the pentobarbital metabolism catalyzed by these two CYPs. These findings suggest that the inhibition of pentobarbital metabolism by empenthrin in mice does not occur in other species including humans.
Related Concept Videos
Anthelminthic Agents
Pharmacokinetics in Pediatric Patients: Drug Metabolism
Nonlinear Pharmacokinetics: Dependence of Elimination Half-Life and Dose Clearance
A study on guinea pigs examined the...
Factors Affecting Drug Biotransformation: Biological
Species differences: Variations in enzyme systems across species can cause disparities in drug metabolism. For instance, humans may metabolize certain drugs faster than rodents, altering therapeutic effects.
Strain differences: Genetic variations within a species can result in differing enzyme activity, impacting drug response and toxicity. For example, some mouse strains may...
Factors Affecting Drug Biotransformation: Physicochemical and Chemical Properties of Drugs
The drug's acidity or basicity is essential in determining the metabolic...
Sedatives and Hypnotics Drugs: Barbiturates

