Acute ethanol administration reduces the antidote effect of N-acetylcysteine after acetaminophen overdose in mice

Concurrent administration of acetaminophen and ethanol: impact on mouse liver and testis

OBJECTIVES

Acetaminophen (paracetamol) and alcohol are widely consumed as analgesic/antipyretic and recreational agent, respectively. High doses of both agents induce liver and male reproductive toxicities. This study investigated the toxicological outcome of concurrent administration of paracetamol and ethanol in the liver and testis in mice.

METHODS

Animals were gavaged paracetamol (250 mg/kg), ethanol (3 g/kg) or paracetamol + ethanol for 2 d. Some groups were sacrificed 12 h after the last dose, while others were sacrificed 21 d posttreatment for reversibility study. Control group received carboxymethylcellulose sodium (0.2%). Serum levels of liver biochemical indices and epididymal sperm were analysed. Histopathological analysis of the liver and testis were also performed.

RESULTS

Alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and bilirubin in serum were elevated (p<0.001); whereas albumin and total protein were reduced (p<0.001) in paracetamol or ethanol groups compared to control. In the combination group, only mild elevation of ALT (p<0.05) was observed. Additionally, hepatocyte necrosis occurred in the livers of paracetamol and ethanol groups, while only mild inflammatory changes were seen in the combination group. All liver indices were normal in reversibility study animals. Furthermore, sperm count, motility, viability and morphology did not change in all treated animals, except that sperm count was decreased (p<0.05) in paracetamol group. Testis histology of all animal groups were normal.

CONCLUSIONS

The results demonstrated that simultaneous treatment with acute paracetamol and ethanol doses will possibly minimize hepatotoxicity and reduction of epididymal sperm reserve by the individual agents, and the toxicities are reversible.

Alcohol exposure and paracetamol-induced hepatotoxicity

Most instances of hepatotoxicity due to paracetamol in the United Kingdom and Australia are the result of large overdoses of the drug taken with suicidal or parasuicidal intent. In contrast, serious hepatotoxicity at recommended or near-recommended doses for therapeutic purposes has been reported, mainly from the United States and in association with chronic alcohol use, leading to the widely held belief that chronic alcoholics are predisposed to paracetamol-related toxicity at relatively low doses. Yet the effects of alcohol on paracetamol metabolism are complex. Studies performed in both experimental animals and humans indicate that chronic alcohol use leads to a short-term, two- to threefold increase in hepatic content of cytochrome P4502E1, the major isoform responsible for the generation of the toxic metabolite from paracetamol, although increased oxidative metabolism of paracetamol at recommended doses has not been demonstrated clinically. A reduced hepatic content of glutathione, required to detoxify the reactive metabolite, has been documented in chronic alcoholics, due probably to associated fasting and malnutrition, providing a metabolic basis for any possible predisposition of this group to hepatotoxicity at relatively low paracetamol doses. Simultaneous alcohol and paracetamol ingestion reduces oxidative metabolism of paracetamol in both rodents and humans, predominantly as a consequence of depletion in cytosol of free NADPH. The possibilities that chronic alcohol use may predispose to paracetamol-related hepatotoxicity and that alcohol taken with paracetamol may protect against it, based on these metabolic observations, are examined in this review.

Influence of acute and chronic alcohol intake on the clinical course and outcome in acetaminophen overdose

BACKGROUND

Animal studies on acetaminophen toxicity suggest that chronic alcohol intake affects the outcome adversely, whereas acute alcohol intake seems protective. Few clinical data are available.

METHODS

We studied 209 consecutive patients with single-dose acetaminophen overdose. The combined influence of independent variables (gender, age, dose, delay to antidote treatment, chronic and acute alcohol intake and nomogram risk group) on dependent variables (death, development of hepatic encephalopathy and biochemical liver markers) was studied using multiple or logistic regression analysis.

RESULTS

Fifty-seven (27.3%) patients had chronic alcohol intake and 45 (21.5%) patients had acute alcohol intake. Forty-four (21.1%) patients developed hepatic coma and 20 (43.5%) of these patients died. Chronic alcohol intake was significantly and independently associated with the development of hepatic coma, with a lower prothrombin index, lower platelet count, higher creatinine and higher bilirubin. The relative risks for hepatic coma and death were 5.3 (95% confidence interval, 2.2-12.4) and 1.4 (95% confidence interval, 0.5-3.9), respectively, in the chronic alcohol intake group compared with the no chronic alcohol intake group. Acute alcohol intake was not significantly associated with any of the dependent variables studied.

CONCLUSIONS

Chronic alcohol intake enhances acetaminophen hepatotoxicity, whereas acute alcohol intake does not affect the clinical course.