Liver necrosis hepatotoxicity

As regards toxicity, pyrazole itself induced hyperplasia of the thyroid, hepatomegaly, atrophy of the testis, anemia and bone marrow depression in rats and mice (72E1198). The 4-methyl derivative is well tolerated and may be more useful than pyrazole for pharmacological and metabolic studies of inhibition of ethanol metabolism. It has been shown (79MI40404) that administration of pyrazole or ethanol to rats had only moderate effects on the liver, but combined treatment resulted in severe hepatotoxic effects with liver necrosis. The fact that pyrazole strongly intensified the toxic effects of ethanol is due to inhibition of the enzymes involved in alcohol oxidation (Section 4.04.4.1.1). 

The purpose of this study was to compare hepatotoxic effects of monobromo-benzene, 3 dibromobenzene isomers, hexabromobenzene and tetrabromobisphenol A with special attention paid to the dynamics of changes of selected indicators of liver necrosis during acute poisoning. 

The mechanism of toxification of isoniazid was investigated in rats pretreated with inducers or inhibitors of microsomal enzymes or an inhibitor of acylamidases. In animals pretreated with the acylamidase inhibitor bis(4-nitrophenyl) phosphate, isoniazid and acetylisoniazid produced less liver necrosis than in control animals. The treatment had no effect on the necrosis due to acetylhydrazine [173], In animals pretreated with inducers of microsomal cytochrome P450 such as phenobarbital, acetylisoniazid, and acetylhydrazine caused markedly increased necrosis, while pretreatment with cytochrome P450 inhibitors decreased necrosis. In contrast, the toxicity of isoniazid and hydrazine was not modified by phenobarbital pretreatment. From these observations, Trimbell et al. [173] concluded that the hydrolysis of acetylisoniazid is a prerequisite for hepatotoxicity, and that microsomal enzymes transform acetylhydrazine, the product of hydrolysis, to a toxic species. 

Hepatic Effects. Carbon tetrachloride has been known for many years to be a powerful hepatotoxic agent in humans and in animals. The principal clinical signs of liver injury in humans who inhale carbon tetrachloride are a swollen and tender liver, elevated levels of hepatic enzyme (aspartate aminotransferase) in the serum, elevated serum bilirubin levels and the appearance of jaundice, and decreased serum levels of proteins such as albumin and fibrinogen (Ashe and Sailer 1942 McGuire 1932 New et al. 1962 Norwood et al. 1950 Straus 1954). In cases of acute lethal exposures, autopsy generally reveals marked liver necrosis with pronounced steatosis (Jennings 1955 Markham 1967 Smetana 1939), and repeated or chronic exposures leads in some cases to fibrosis or cirrhosis (McDermott and Hardy 1963). 

Haloalkanes. Certain haloalkanes and haloalkane-containing mixtures have been demonstrated to potentiate carbon tetrachloride hepatotoxicity. Pretreatment of rats with trichloroethylene (TCE) enhanced carbon tetrachloride-induced hepatotoxicity, and a mixture of nontoxic doses of TCE and carbon tetrachloride elicited moderate to severe liver injury (Pessayre et al. 1982). The researchers believed that the interaction was mediated by TCE itself rather than its metabolites. TCE can also potentiate hepatic damage produced by low (10 ppm) concentrations of carbon tetrachloride in ethanol pretreated rats (Ikatsu and Nakajima 1992). Acetone was a more potent potentiator of carbon tetrachloride hepatotoxicity than was TCE, and acetone pretreatment also enhanced the hepatotoxic response of rats to a TCE-carbon tetrachloride mixture (Charbonneau et al. 1986). The potentiating action of acetone may involve not only increased metabolic activation of TCE and/or carbon tetrachloride, but also possible alteration of the integrity of organelle membranes. Carbon tetrachloride-induced liver necrosis and lipid peroxidation in the rat has been reported to be potentiated by 1,2- dichloroethane in an interaction that does not involve depletion of reduced liver glutathione, and that is prevented by vitamin E (Aragno et al. 1992). 

Cottrell et al. (1996) reported that a single oral dose of coumarin produced liver necrosis in mice 200 mg/kg bw coumarin was hepatotoxic to both C3H/He and DBA/2 mice. Hepatotoxicity was characterized by an increase in plasma aminotransferase activity, mild subcapsular linear hepatocyte necrosis and, in some C3H/He mice, centrilobular necrosis. Mice were pretreated with (3-naphthoflavone (80 mg/kg bw), Aroclor 1254 (54, 125 or 162 mg/kg bw) or vehicle alone by intraperitoneal injection for three consecutive days. Twenty-four hours later, a single dose of coumarin (200 mg/kg bw) or vehicle was administered by gavage. Pretreatment with... 

Macrovesicular steatosis can be attributed to alcohol or cocaine, but massive liver necrosis is more probably due to cocaine. The mechanisms of cocaine hepatotoxicity, such as increased lipid peroxidation, free radical activity, and impaired calcium sequestration, may be potentiated by alcohol. 

Hepatotoxicity has been reported with single-dose dacarbazine (2,3), presenting as acute liver necrosis with hepatic venous thrombosis, which can be fatal. 

Nitrosamines are strong hepatotoxic agents. Large, acute doses produce liver necrosis and hemorrhages in the liver and other tissues. 

Jewell H, Maggs JL, Harrison AC et al (1995) Role of hepatic metabolism in the bioactivation and detoxication of amodiaquine. Xenobiotica 25 199-217 follow DJ, Mitchell JR, Zampaglione N et al (1974) Bromobenzene-induced liver necrosis. Protective role of glutathione and evidence for 3, 4-bromobenzene oxide as the hepatotoxic metabolite. Pharmacology 11 151-169... 

J. R. Bromobenzene induced liver necrosis. Protective role of glutathione and evidence for 3,4-bromobenzene oxide as the hepatotoxic intermediate. Pharmacology, 1974, 11,... 

The acute toxicity of chlordane in rats increased when rats were fed protein deficient diets (Boyd and Taylor 1969). Chlordane treatment has also been demonstrated to enhance the hepatotoxic effects produced by carbon tetrachloride in rats, as indicated by its effect on SGPT levels, presumably by inducing the metabolism of carbon tetrachloride to its toxic metabolite (Mahon et al. 1978 Stenger et al. 1975). On the other hand, chlordane provided some protection against carbon tetrachloride-induced liver necrosis in rats, possibly by inducing a type of cytochrome P-450 with diminished ability to metabolize carbon tetrachloride to its toxic metabolite (Mahon et al. 1978). Pretreatment of rats with chlordane accelerated the metabolism of lindane, presumably by the same mechanism (Chadwick et al. 1977). 

Hepatotoxicity does not occur at recommended doses of acetaminophen. Administration of 2 g, or twice the recommended dose, of intravenous paracetamol in healthy subjects has been shown to stay far below the threshold of hepatotoxicity. When ingested at high doses, acetaminophen is metabolized to JV-acetyl-p-benzoquinone-imine (NAPQI). NAPQI is rapidly conjugated with glutathione to a nontoxic compound. The depletion of glutathione results in the accumulation of NAPQI that is responsible for liver injury. Acetaminophen has a narrow therapeutic window and even minor overdoses may cause severe hepatic injury. Liver necrosis occurs at 7.5-10 g of acetaminophen. 

Yellow phosphorus was the first identified liver toxin. It causes accumulation of lipids in the liver. Several liver toxins such as chloroform, carbon tetrachloride, and bromobenzene have since been identified. I he forms of acute liver toxicity are accumulation of lipids in the liver, hepartxiellular necrosis, iii-trahepatic cholestasis, and a disease state that resembles viral hepatitis. The types of chrome hepatotoxicity are cirrhosis and liver cancer. 

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