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Abstracts

LE Magazine December 2007
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Acetaminophen

Severe hepatotoxicity after therapeutic doses of acetaminophen.

BACKGROUND: Acetaminophen overdose is a frequent cause of acute liver failure. Controversy exists over the rare association of severe hepatotoxicity or acute liver failure with therapeutic doses of acetaminophen. CASE SUMMARY: A 45-year-old white man weighing 85 kg with asymptomatic HIV, hepatitis B virus, and hepatitis C virus (HCV) infection presented with signs of severe hepatotoxicity: aspartate aminotransferase (AST), 8,581 IU/L; alanine aminotransferase (ALT), 5,433 IU/L; L-lactate dehydrogenase, 13,641 IU/L; and prothrombin international normalized ratio, 2.15. He reported taking acetaminophen 1,000 mg QID for the previous 4 days and 1,000 mg that morning because of a febrile illness. Immediate administration of continuous IV N-acetylcysteine 150 mg/kg for the first 90 minutes and then 50 mg/kg q4h for the next 3 days was followed by clinical improvement and a rapid decrease in AST and ALT. AST levels decreased from 8,581 to 42 IU/L within 11 days. Several potential risk factors for acetaminophen hepatotoxicity (ie, chronic alcohol, tobacco, and opiate consumption, malnutrition, illness-induced starvation, HIV infection, and HCV infection) were present in this patient. CONCLUSIONS: This patient with multiple risk factors and severe hepatotoxicity after therapeutic dosage of acetaminophen was successfully treated with N-acetylcysteine.

Clin Ther. 2006 May;28(5):755-60

Estimates of acetaminophen (Paracetomal)-associated overdoses in the United States.

OBJECTIVE: To estimate the number of acetaminophen-associated overdoses in the United States and identify possible risk factors for intervention. METHODS: The investigators obtained estimates of acetaminophen-associated overdoses using different national databases. Two emergency room databases, a hospital discharge database, a national mortality file, and a poison surveillance database were used to identify cases. The FDA’s spontaneous reporting system was searched to identify possible root causes for overdoses. RESULTS: Analysis of national databases show that acetaminophen-associated overdoses account for about 56,000 emergency room visits and 26,000 hospitalizations yearly. Analysis of national mortality files shows 458 deaths occur each year from acetaminophen-associated overdoses; 100 of these are unintentional. The poison surveillance database showed near-doubling in the number of fatalities associated with acetaminophen from 98 in 1997 to 173 in 2001. AERS data describe a number of possible causes for unintentional acetaminophen-associated overdoses. CONCLUSIONS: Each year a substantial numbers of Americans experience intentional and unintentional acetaminophen-associated overdoses that, in severe cases, lead to serious illness and possible death. This summary of a series of analyses highlights the need for strategies to reduce this public health burden.

Pharmacoepidemiol Drug Saf. 2006 Jun;15(6):398-405

Acetaminophen-induced acute liver failure: results of a United States multicenter, prospective study.

Severe acetaminophen hepatotoxicity frequently leads to acute liver failure (ALF). We determined the incidence, risk factors, and outcomes of acetaminophen-induced ALF at 22 tertiary care centers in the United States. Detailed prospective data were gathered on 662 consecutive patients over a 6-year period fulfilling standard criteria for ALF (coagulopathy and encephalopathy), from which 275 (42%) were determined to result from acetaminophen liver injury. The annual percentage of acetaminophen-related ALF rose during the study from 28% in 1998 to 51% in 2003. Median dose ingested was 24 g (equivalent to 48 extra-strength tablets). Unintentional overdoses accounted for 131 (48%) cases, intentional (suicide attempts) 122 (44%), and 22 (8%) were of unknown intent. In the unintentional group, 38% took two or more acetaminophen preparations simultaneously, and 63% used narcotic-containing compounds. Eighty-one percent of unintentional patients reported taking acetaminophen and/or other analgesics for acute or chronic pain syndromes. Overall, 178 subjects (65%) survived, 74 (27%) died without transplantation, and 23 subjects (8%) underwent liver transplantation; 71% were alive at 3 weeks. Transplant-free survival rate and rate of liver transplantation were similar between intentional and unintentional groups. In conclusion, acetaminophen hepatotoxicity far exceeds other causes of acute liver failure in the United States. Susceptible patients have concomitant depression, chronic pain, alcohol or narcotic use, and/or take several preparations simultaneously. Education of patients, physicians, and pharmacies to limit high-risk use settings is recommended.

Hepatology. 2005 Dec;42(6):1364-72

Aminotransferase elevations in healthy adults receiving 4 grams of acetaminophen daily: a randomized controlled trial.

CONTEXT: During a clinical trial of a novel hydrocodone/acetaminophen combination, a high incidence of serum alanine aminotransferase (ALT) elevations was observed. OBJECTIVE: To characterize the incidence and magnitude of ALT elevations in healthy participants receiving 4 g of acetaminophen daily, either alone or in combination with selected opioids, as compared with participants treated with placebo. DESIGN, SETTING, AND PARTICIPANTS: A randomized, single-blind, placebo-controlled, 5-treatment, parallel-group, inpatient, diet-controlled (meals provided), longitudinal study of 145 healthy adults in 2 US inpatient clinical pharmacology units. INTERVENTION: Each participant received either placebo (n = 39), 1 of 3 acetaminophen/opioid combinations (n = 80), or acetaminophen alone (n = 26). Each active treatment included 4 g of acetaminophen daily, the maximum recommended daily dosage. The intended treatment duration was 14 days. Main Outcomes Serum liver chemistries and trough acetaminophen concentrations measured daily through 8 days, and at 1- or 2-day intervals thereafter. RESULTS: None of the 39 participants assigned to placebo had a maximum ALT of more than 3 times the upper limit of normal. In contrast, the incidence of maximum ALT of more than 3 times the upper limits of normal was 31% to 44% in the 4 treatment groups receiving acetaminophen, including those participants treated with acetaminophen alone. Compared with placebo, treatment with acetaminophen was associated with a markedly higher median maximum ALT (ratio of medians, 2.78; 95% confidence interval, 1.47-4.09; P<.001). Trough acetaminophen concentrations did not exceed therapeutic limits in any participant and, after active treatment was discontinued, often decreased to undetectable levels before ALT elevations resolved. CONCLUSIONS: Initiation of recurrent daily intake of 4 g of acetaminophen in healthy adults is associated with ALT elevations and concomitant treatment with opioids does not seem to increase this effect. History of acetaminophen ingestion should be considered in the differential diagnosis of serum aminotransferase elevations, even in the absence of measurable serum acetaminophen concentrations.

JAMA. 2006 Jul 5;296(1):87-93

Drug-induced cardiovascular disorders.

As the variety and range of pharmaceutical agents available to the medical profession continues to expand, one unavoidable effect will be an increase in drug-induced disease, including cardiovascular disorders. However, given the high rates of cardiovascular disease and prevalence of recognised cardiovascular risk factors in the population, it is sometimes impossible to conclusively attribute any individual patients’ ill health to one particular drug. As a result, the relationship between drugs and cardiovascular disease is often difficult to quantify. This review discusses specific forms of drug-induced cardiovascular disease such as heart failure, left ventricular systolic dysfunction, hypertension and arrhythmia. Suspected culprit drugs for all disorders are highlighted. Specific attention is given to certain drug groups with a strong association with one or more forms of cardiovascular disease: these include anthracyclines, antipsychotics, NSAIDs and cyclo-oxygenase 2 inhibitors. Additionally, advice is offered on how physicians might distinguish drug-induced cardiovascular disorders from other aetiologies.

Drug Saf. 2007;30(9):783-804

How to advise aspirin use in patients who need NSAIDs.

NSAIDs are widely used all over the world. NSAID use is rising due to increasing availability without a prescription, use of aspirin for prevention of thrombotic disorders and the ageing population. Aspirin is used as an analgesic drug in many countries, but the main current indication is low-dose aspirin for the prevention of cardiovascular events. However, NSAIDs and aspirin use account for approximately 20-25% of all reported drug adverse events. Most of those are gastrointestinal including dyspepsia, hemorrhage, perforation and even death. The COX-2- selective inhibitors (coxibs) have demonstrated equivalent efficacy to nonspecific NSAIDs in the management of arthritis and pain but have less gastrointestinal adverse events, although coxibs and probably all NSAIDs, significantly increase risk of serious thromboembolic events. Concomitant use of low-dose aspirin is present in more than 20% of all patients taking either NSAIDs or coxibs, thus increasing the risk of gastrointestinal side effects. Furthermore, at present, it is not known whether aspirin decreases the cardiovascular risks of COX-2 inhibitors or NSAIDs. Appropriate strategies for gastrointestinal risk reduction with NSAIDs and aspirin must consider the overall health status of our patients including the presence of cardiovascular and gastrointestinal risk factors. Use of the lowest possible dose of these drugs, gastroprotectants, especially proton pump inhibitors and Helicobacter pylori eradication will reduce the risk of gastrointestinal side effects in patients taking low-dose aspirin and NSAIDs or coxibs.

Curr Pharm Des. 2007;13(22):2248-60

N-Acetylcysteine--a safe antidote for cysteine/glutathione deficiency.

Glutathione (GSH) deficiency is associated with numerous pathological conditions. Administration of N-acetylcysteine (NAC), a cysteine prodrug, replenishes intracellular GSH levels. NAC, best known for its ability to counter acetaminophen toxicity, is a safe, well-tolerated antidote for cysteine/GSH deficiency. NAC has been used successfully to treat GSH deficiency in a wide range of infections, genetic defects and metabolic disorders, including HIV infection and COPD. Over two-thirds of 46 placebo-controlled clinical trials with orally administered NAC have indicated beneficial effects of NAC measured either as trial endpoints or as general measures of improvement in quality of life and well-being of the patients.

Curr Opin Pharmacol. 2007 Aug;7(4):355-9. Epub 2007 Jun 29

Whey protein concentrate promotes the production of glutathione (GSH) by GSH reductase in the PC12 cell line after acute ethanol exposure.

Excessive ethanol consumption may increase the production of reactive oxygen species (ROS), which results in the damage of tissues, especially the neurons and glial cells in the central nervous system (CNS). The purpose of this study is to evaluate the effects of whey protein concentrate (WPC) on the glutathione (GSH) status after acute ethanol exposure in the pheochromocytoma (PC12) cell line. In this study, we assayed the cell viability, the percentage of lactate dehydrogenase released (% LDH released), the level of GSH, and the activity of GSH reductase (GRx). The results showed that with the supplement of WPC, the cell viability displayed no significant difference after acute exposure of ethanol in groups with or without ethanol treatment. The ethanol-induced cytotoxicity showed a slight decrease, and the level of GSH showed a significant increase. The activity of GRx significantly increased when 0.1, 10mg/ml of WPC was supplied. In conclusion, these results suggest that WPC in a moderate concentration should be a precursor agent to promote the production of GSH and will enhance the antioxidant capacity in the PC12 cell line.

Food Chem Toxicol. 2006 Apr;44(4):574-8. Epub 2005 Dec 19

Silymarin protects against paracetamol-induced lipid peroxidation and liver damage.

The effect of silymarin on liver damage induced by acetaminophen (APAP) intoxication was studied. Wistar male rats pretreated (72 h) with 3-methylcholanthrene (3-MC) (20 mg kg-1 body wt. i.p.) were divided into three groups: animals in group 1 were treated with acetaminophen (APAP) (500 mg kg-1 body wt. p.o.), group 2 consisted of animals that received APAP plus silymarin (200 mg kg-1 body wt. p.o.) 24 h before APAP, and rats in group 3 (control) received the equivalent amount of the vehicles. Animals were sacrificed at different times after APAP administration. Reduced glutathione (GSH), lipid peroxidation and glycogen were measured in liver and alkaline phosphatase (AP), gamma-glutamyl transpeptidase (GGTP) and glutamic pyruvic transaminase (GPT) activities were measured in serum. After APAP intoxication, GSH and glycogen decreased very fast (1 h) and remained low for 6 h. Lipid peroxidation increased three times over the control 4 and 6 h after APAP treatment. Enzyme activities increased 18 h after intoxication. In the group receiving APAP plus silymarin, levels of lipid peroxidation and serum enzyme activities remained within the control values at any time studied. The fall in GSH was not prevented by silymarin, but glycogen was restored at 18 h. It was concluded that silymarin can protect against APAP intoxication through its antioxidant properties, possibly acting as a free-radical scavenger.

J Appl Toxicol. 1992 Dec;12(6):439-42

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