Evidence that coal tar is a mixed inducer of microsomal drug-metabolizing enzymes.
Toxicol Lett 1982 May; 11(3-4):221-227
The effect of coal-tar (8007452) on microsomal drug metabolizing enzymes was investigated in neonatal rats. Four day old rats were treated topically with 100 microliters of coal-tar, or 3- methylcholanthrene or Aroclor-1254 for comparison. Exposure to coal- tar resulted in the induction of hepatic cytosolic glutathione-S- transferase and microsomal epoxide-hydrolase and aminopyrine-N- demethylase activities. Treatment with coal-tar resulted in a 1 nanometer shift to the blue region in the wavelength maximum of the hepatic microsomal hemoprotein cytochrome-P-450, a result which was analogous to the effect of the polychlorinated biphenyl Aroclor- 1254. The authors conclude from these findings that therapeutic coal-tar contains both type-I and type-II inducers of hepatic drug metabolizing enzymes. The findings do not indicate that the responses observed are due to a single constituent or to multiple constituents of coal-tar inasmuch as the response may be due wholly or in part to unidentified factor(s) acting alone or in combination. It is also likely that the observed response of drug metabolizing enzyme activities to coal-tar may be the result of synergism between several constituents whose individual concentrations may be insufficient to induce the observed responses.
NIOSH-Publication; NIOSH-Grant; Dermatitis; Laboratory-animals; Skin-exposure; Liver-enzymes; Enzyme-activity; Hydrocarbons
Medicine Cleveland V a Hospital 10701 East Blvd Cleveland, Ohio 44106
Case Western Reserve University, Cleveland, Ohio