The results from previous animal studies indicate that while cocaine alone is not a potent hepatotoxin, its administration in conjunction with other drugs may result in substantial hepatic injury. These results are supported by clinical observations, including reports of significant hepatic injury among users of cocaine with other substances of abuse. While there is a mechanistic basis of predict that variety of substances of abuse may potentiate cocaine hepatotoxicity, there has been no systematic examination of this phenomenon, nor has a basis been established for the extrapolation of studies of cocaine hepatoxicity in animals to man. The hepatic bioactivation pathway shown to result in liver toxicity in mice in previous studies will be examined in human hepatic microsomes. Rates of formation of metabolites and identification of responsible enzymes will be used in conjunction with a measurement of in vitro toxicity to define similarities and differences in inherent mechanisms leading to cocaine-induced liver damage. Further experiments will utilize the mouse model to identify mixed substance abuse scenarios in which cocaine use carries the highest risk of hepatic injury. Co- exposure to morphine, butorphanol, alcohol, amphetamine and pentobarbital will be studied, as each of these agents represents a group of drugs upon which there is a mechanistic basis to predict potentiation of cocaine-induced hepatotoxicity. Dose-response and temporal relationships will be established, as well as the influence of opiate or barbiturate tolerance. When exposure regimens which result in potentiation (or inhibition) of cocaine hepatotoxicity are identified, the mechanism for the interaction will be studied through a series of experiments in which effects on toxic metabolite formation and hepatocellular glutathione status are monitored. These experiments will collectively provide information essential to our understanding of the types of substance abuse circumstances which may lead to significant health consequences from the use of cocaine.

Agency
National Institute of Health (NIH)
Institute
National Institute on Drug Abuse (NIDA)
Type
Research Project (R01)
Project #
1R01DA006601-01
Application #
3213255
Study Section
Pharmacology I Research Subcommittee (DABR)
Project Start
1989-09-30
Project End
1991-08-31
Budget Start
1989-09-30
Budget End
1990-08-31
Support Year
1
Fiscal Year
1989
Total Cost
Indirect Cost
Name
University of Florida
Department
Type
Organized Research Units
DUNS #
073130411
City
Gainesville
State
FL
Country
United States
Zip Code
32611
Ndikum-Moffor, Florence M; Roberts, Stephen M (2003) Cocaine-protein targets in mouse liver. Biochem Pharmacol 66:105-13
Boess, F; Ndikum-Moffor, F M; Boelsterli, U A et al. (2000) Effects of cocaine and its oxidative metabolites on mitochondrial respiration and generation of reactive oxygen species. Biochem Pharmacol 60:615-23
Ndikum-Moffor, F M; Munson, J W; Bokinkere, N K et al. (1998) Immunochemical detection of hepatic cocaine-protein adducts in mice. Chem Res Toxicol 11:185-92
Ndikum-Moffor, F M; Schoeb, T R; Roberts, S M (1998) Liver toxicity from norcocaine nitroxide, an N-oxidative metabolite of cocaine. J Pharmacol Exp Ther 284:413-9
Roberts, S M; Phillips, D L; Tebbett, I R (1995) Increased blood and brain cocaine concentrations with ethanol cotreatment in mice. Drug Metab Dispos 23:664-6
Roberts, S M; Harbison, R D; James, R C (1993) Inhibition by ethanol of the metabolism of cocaine to benzoylecgonine and ecgonine methyl ester in mouse and human liver. Drug Metab Dispos 21:537-41
Roberts, S M; Roth, L; Harbison, R D et al. (1992) Cocaethylene hepatotoxicity in mice. Biochem Pharmacol 43:1989-95
Roth, L; Harbison, R D; James, R C et al. (1992) Cocaine hepatotoxicity: influence of hepatic enzyme inducing and inhibiting agents on the site of necrosis. Hepatology 15:934-40
Roberts, S M; Munson, J W; James, R C et al. (1992) An assay for cocaethylene and other cocaine metabolites in liver using high-performance liquid chromatography. Anal Biochem 202:256-61
Roberts, S M; Harbison, R D; James, R C (1991) Human microsomal N-oxidative metabolism of cocaine. Drug Metab Dispos 19:1046-51