Acute Acetaminophen Overdose Research Articles

The effect of diazepam in the recovery of rabbits from acute acetaminophen intoxication.

We have recently shown that diazepam can reduce mortality of acute iron overdose in rats. The mechanism for that effect is not yet defined. Our objective in the present study was to assess whether diazepam can similarly reduce mortality of experimental acute acetaminophen intoxication. Survival of rabbits was compared among four groups receiving 3 g/kg (body weight) of acetaminophen (LD40) orally each, followed by: 1) nothing (group I), 2) one oral dose of 140 mg/kg N-acetylcystein (NAC) an hour later (group II), 3) intramuscular injection of 7 mg/kg diazepam (group III), 4) intramuscular injection of 7 mg/kg diazepam and one oral dose of 140 mg/kg NAC an hour later (group IV). 37.5% of rabbits in group I died after 16 hours, whereas none of the rabbits in group III died, (p = 0.04). No animal died during the 96-hour observation period in groups II and IV. Two and four hours post drug administration, acetaminophen plasma concentrations (APC) were significantly lower among rabbits in group III than in group I (p = 0.0007 and 0.01, respectively) and significantly lower among rabbits in group IV than in those in group II (p<0.0001 and p = 0.03, respectively). Acetaminophen plasma concentrations 2 hours after drug administration were also significantly lower among rabbits in group III than in those in group II (p = 0.0002). Seven and 24 hours after dosage, APC tended to be higher among rabbits in group III than in those in group I, but not significantly so. Administration of diazepam without NAC did not prevent liver and renal dysfunction. We conclude that early administration of diazepam in acute experimental acetaminophen overdose in rabbits reduced APC and mortality, probably by slowing intestinal motility, which resulted in delayed acetaminophen absorption from the gastrointestinal tract.

Acetaminophen Toxicity: OPPOSITE EFFECTS OF TWO FORMS OF GLUTATHIONE PEROXIDASE

Acetaminophen is one of the most extensively used analgesics/antipyretics worldwide, and overdose or idiopathic reaction causes major morbidity and mortality in its victims. Research into the mechanisms of toxicity and possible therapeutic intervention is therefore essential. In this study, the response of transgenic mice overexpressing human antioxidant enzymes to acute acetaminophen overdose was investigated. Animals overexpressing superoxide dismutase or plasma glutathione peroxidase demonstrated dramatic resistance to acetaminophen toxicity. Intravenous injection of glutathione peroxidase provided normal mice with nearly complete protection against a lethal dose of acetaminophen. Surprisingly, animals overexpressing intracellular glutathione peroxidase in the liver were significantly more sensitive to acetaminophen toxicity compared with nontransgenic littermates. This sensitivity appears to be due to the inability of these animals to efficiently recover glutathione depleted as a result of acetaminophen metabolism. Finally, the results suggest that glutathione peroxidase overexpression modulates the synthesis of several acetaminophen metabolites. Our results demonstrate the ability of glutathione peroxidase levels to influence the outcome of acetaminophen toxicity.

Extended-Release Acetaminophen Overdose

<h3>To the Editor.</h3> —There were 102 619 cases of ingestion of acetaminophen-containing products, including 100 deaths, reported in the United States in 1994.¹Management of acute acetaminophen overdose is guided by the Rumack-Matthew nomogram, which assumes acetaminophen absorption in acute overdose is complete by 4 hours after ingestion.²In August 1994, McNeil Pharmaceuticals (Fort Washington, Pa) introduced Tylenol Extended Relief, the first extended-release formulation of acetaminophen available in the United States. Patients presenting after overdose with extended release (ER) acetaminophen (Tylenol ER) which contains 325 mg of immediate-release acetaminophen and 325 mg of extended-release acetaminophen per tablet, pose a dilemma because the kinetics of acetaminophen ER in overdose are unknown, and it is not known whether physicians can rely on the nomogram to facilitate treatment. Douglas et al³found no difference in time to peak concentration between acetaminophen ER and immediate-release acetaminophen in volunteers who ingested 75

Cimetidine as adjunctive treatment for acetaminophen overdose

The aim of this study was to determine if cimetidine in addition to N-acetylcysteine and standard supportive care provide additional hepatoprotection following acute acetaminophen poisoning. It was designed as a prospective study with alternate month treatment protocol, and the work was carried out at a regional certified poison information centre. For a 2-year period, consultations received by the Rocky Mountain Poison Center involving acute acetaminophen overdose patients with a serum level above the nomogram line, but who would not receive N-acetylcystine therapy until at least 8 h postingestion, were prospectively evaluated for adjunctive treatment with cimetidine. All patients received standard supportive therapy and N-acetylcysteine treatment. During odd numbered months, cimetidine 300 mg was administered intravenously every 6 h for the duration of N-acetylcysteine therapy. Forty-one cimetidine treated patients were compared to 66 patients in the control group. The peak measured AST levels (+/- s.e.) were 1259+/-330 and 1301+/-451 for the control and cimetidine treatment groups, respectively (P = 0.94). Fourteen of 64 patients (21%) in the control group and 8/41 patients (20%) in the cimetidine group developed an AST > 1000 IUL-1. There were no statistical differences between the cimetidine-treated and control groups when classified by AST < 100 IUL-1, 100-1000 IUL-1, or > 1000 IUL-1. The addition of cimetidine therapy to standard N-acetylcysteine treatment did not provide additional hepatoprotection in acutely acetaminophen poisoned patients when treatment was started later than 8 h post overdose.(ABSTRACT TRUNCATED AT 250 WORDS)

A prospective evaluation of the effect of activated charcoal before oral N-acetylcysteine in acetaminophen overdose

To evaluate whether activated charcoal (AC) reduces the efficacy of subsequent oral N-acetylcysteine therapy during acute acetaminophen overdose. Prospective observational case series of all acute acetaminophen overdoses reported to three certified regional poison centers. TYPES OF PATIENTS: All patients with acute acetaminophen overdose in whom N-acetylcysteine therapy was initiated within 16 hours after ingestion. All patients were treated with oral N-acetylcysteine therapy for 72 hours. The decision to use AC was left to the treating physician without input from the investigator. One hundred twenty-two patients were evaluated. Maximum recorded SGOT levels of more than 125 U/mL were defined as evidence of hepatotoxicity. AC was used in addition to N-acetylcysteine in 82 of 122 patients. Hepatotoxicity developed in four of 82 patients who received AC versus ten of 40 patients who did not receive AC (P < .005). An increasing dose of N-acetylcysteine provided no additional benefit (P > .05). Spacing the administration of AC and oral N-acetylcysteine less than or more than two hours apart did not affect outcome (P > .05). Administration of AC before the administration of oral N-acetylcysteine in acetaminophen overdose does not reduce the efficacy of N-acetylcysteine therapy and may provide some additional hepatoprotective benefit. The practice of increasing the dose of oral N-acetylcysteine therapy after the administration of AC appears unwarranted.

Potentiation of Acute Acetaminophen Lethality by Selenium and Vitamin E Deficiency in Mice

The effects of selenium, vitamin E, and DL-methionine deficiency on the acute lethality and hepatotoxicity of acetaminophen in male CD-1 mice were studied. Vitamin E and selenium deficiencies led to an increase in the acute lethality of acetaminophen, with a decrease in the LD50 from 376 to 84 mg/kg. These dietary deficiencies impaired the inducibility of the hepatic microsomal mixed function oxidase system by phenobarbital, but on the basis of the covalent binding of acetaminophen to microsomes, these treatments did not alter the activation of acetaminophen to a reactive intermediate by this system. Addition of methionine to the deficient diet restored hepatic glutathione content to control levels but did little to protect against the acute lethality of acetaminophen. In methionine-supplemented animals, the addition of either selenium or vitamin E increased the LD50 of acetaminophen to 167 and 200 mg/kg, respectively. Administration of a sublethal, toxic dose of acetaminophen (LD30) to the methionine-supplemented and selenlum- and vitamin E-deficient mice did not produce any hepatic damage as evidenced by a lack of plasma aminotransferase elevation. In view of the known antioxidant effects of vitamin E and selenium, these data suggest the involvement of a reactive radical in the acute lethality of acetaminophen and further suggest that death from acute acetaminophen overdose in chronic selenium- and vitamin E-deficient mice may be unrelated to liver necrosis.

Acetaminophen overdose: A 48-hour intravenous N-acetylcysteine treatment protocol

To determine the safety and efficacy of a 48-hour IV N-acetylcysteine (IV NAC) treatment protocol for acute acetaminophen overdose. Nonrandomized trial open to all eligible patients. Multicenter; hospitals included moderate- and high-volume private, university, and municipal hospitals in urban and suburban settings. Two hundred twenty-three patients were entered. Of these, 179 met inclusion criteria: acute acetaminophen overdose, plasma acetaminophen concentration above the treatment nomogram line, treatment with IV NAC according to the protocol, and sufficient data to determine outcome. IV NAC treatment consisted of a loading dose of 140 mg/kg followed by 12 doses of 70 mg/kg every four hours. Patients were grouped for analysis according to risk group based on the initial plasma acetaminophen concentration. Hepatotoxicity (aspartate aminotransferase or alanine aminotransferase of more than 1,000 IU/L) developed in 10% (five of 50) of patients at "probable risk" when IV NAC was started within ten hours of acetaminophen ingestion and in 27.1% (23 of 85) when therapy was begun after ten to 24 hours. Among "high-risk" patients first treated 16 to 24 hours after overdose, hepatotoxicity occurred in 57.9% (11 of 19). There were two deaths (two of 179, 1.1%). Adverse reactions resulting from NAC occurred in 32 of 223 cases (14.3%), consisting in 29 of 32 patients (91% of reactions) of transient, patchy, skin erythema or mild urticaria during the loading dose that did not require discontinuation of therapy. This 48-hour IV NAC protocol is safe and effective antidotal therapy for acetaminophen overdose. Based on available data, it is equal to 72-hour oral and 20-hour IV treatment protocols when started early and superior to the 20-hour IV regimen when treatment is delayed. Further study will be required to determine its relative efficacy in the high-risk patient treated very late.

Cimetidine as adjunctive treatment for acetaminophen overdose

The aim of this study was to determine if cimetidine in addition to N-acetylcysteine and standard supportive care provide additional hepatoprotection following acute acetaminophen poisoning. It was designed as a prospective study with alternate month treatment protocol, and the work was carried out at a regional certified poison information centre. For a 2-year period, consultations received by the Rocky Mountain Poison Center involving acute acetaminophen overdose patients with a serum level above the nomogram line, but who would not receive N-acetylcystine therapy until at least 8 h postingestion, were prospectively evaluated for adjunctive treatment with cimetidine. All patients received standard supportive therapy and N-acetylcysteine treatment. During odd numbered months, cimetidine 300 mg was administered intravenously every 6 h for the duration of N-acetylcysteine therapy. Forty-one cimetidine treated patients were compared to 66 patients in the control group. The peak measured AST levels (+/- s.e.) were 1259+/-330 and 1301+/-451 for the control and cimetidine treatment groups, respectively (P = 0.94). Fourteen of 64 patients (21%) in the control group and 8/41 patients (20%) in the cimetidine group developed an AST > 1000 IUL-1. There were no statistical differences between the cimetidine-treated and control groups when classified by AST 1000 IUL-1. The addition of cimetidine therapy to standard N-acetylcysteine treatment did not provide additional hepatoprotection in acutely acetaminophen poisoned patients when treatment was started later than 8 h post overdose.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute acetaminophen overdose during pregnancy: Riggs BS, Bronstein AC, Kulig K, et al Obstet Gynecol 74:247–253 Aug 1989

Acute acetaminophen overdose during pregnancy: Riggs BS, Bronstein AC, Kulig K, et al Obstet Gynecol 74:247–253 Aug 1989

Prediction of acetaminophren level from clinical history of overdose using a pharmacokinetic model

A retrospective study was undertaken to determine the accuracy of predicting acetaminophen levels using the pharmacokinetic equation for first-order absorption and elimination of a single oral ingestion, (Formula: see text) Forty-four acute adult acetaminophen overdoses were studied during a 22-month period. Eighty levels drawn from 0 to 16 hours after ingestion were evaluated. To standardize the data, only first levels drawn in patients without prior spontaneous or ipecac-induced vomiting were analyzed (n = 26). Of these 26 levels, eight (31%) were drawn from 0 to two hours after ingestion, eight (31%) from two to four hours, and ten (38%) from four to 16 hours, with correlations of 0.59, 0.85, and 0.98, respectively. To determine the accuracy of predicting four-hour levels, five patients with first levels drawn at four hours, prior to vomiting, were evaluated. Substituting appropriate constants, the condensed equation, Cp4h = (0.59) (mg/kg dose), was used to predict the four-hour level (r = 0.99). Preliminary data suggest the ability to accurately predict four-hour acetaminophen levels from ingestion history alone using pharmacokinetic equations.

Acetaminophen Toxicity Report of a Case and Review of the Literature

A case of acute acetaminophen overdose is presented. After ingesting approximately 36 g of acetaminophen, the patient experienced severe hepatic damage with total bilirubin reaching a high of 26.5 mg/100 ml. The complications and present methods available for treating acute acetaminophen overdose are discussed.