Lipid intolerance does not account for susceptibility to alcoholic and gallstone pancreatitis

Hypertriglyceridemia may contribute to stroke and pancreatitis: A case report and review of the literature

Hypertriglyceridemia (HTG) is one of the most common clinical dyslipidemia. Nevertheless, stroke and acute pancreatitis co-occurrence due to hypertriglyceridemia are extremely rare. We present a case of hypertriglyceridemia-associated stroke and pancreatitis in a 39-year-old woman. The patient's laboratory tests reported high triglyceride concentrations beyond the instrument's detection range, and radiological examination showed typical signs of cerebral infarction and acute pancreatitis. The patient received combined blood purification therapy, intravenous thrombolysis with urokinase, and conservative treatment of pancreatitis. We discuss the clinical features, pathogenesis, diagnosis, and treatment of hypertriglyceridemic stroke and pancreatitis combined with the relevant literature. We reviewed the mechanisms by which triglycerides contribute to atherosclerosis and acute pancreatitis. We point out the superiority of combined blood purification therapy and caution physicians about the effects of prescribed drugs on blood lipids.

Pyruvate and Glutamine Define the Effects of Cholecystokinin and Ethanol on Mitochondrial Oxidation, Necrosis, and Morphology of Rat Pancreatic Acini

OBJECTIVES

The objective of this study was to test whether pyruvate and glutamine affect the ethanol and cholecystokinin (CCK) effects on the mitochondrial function, viability, and morphology of rat pancreatic acini.

METHODS

Respiration was measured with Clark oxygen electrode. Mitochondrial membrane potential, reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H), cell morphology, and viability were studied with fluorescence microscopy.

RESULTS

In vitro, CCK (0.1 nM) caused pyruvate-dependent stimulation of basal and uncoupled respiration, and the effects were abolished by ethanol (20 mM). The combination of ethanol with CCK (2 hours) caused necrosis of approximately 40% acinar cells in medium with glucose, but not with pyruvate and/or glutamine. Cholecystokinin (10 nM) or ethanol with 0.1 nM CCK caused plasma membrane blebbing not related to apoptosis only when both glutamine and pyruvate were present. Glutamine, but not pyruvate, decreased NAD(P)H level and prevented the effects of ethanol with CCK on mitochondrial membrane potential and NAD(P)H, but, in combination with CCK and ethanol, decreased the uncoupled respiration. In vivo, the combination of ethanol (4 g/kg) and CCK (20 pmol/kg) suppressed basal and uncoupled respiration and caused acinar cell blebbing, but not necrosis.

CONCLUSIONS

The lack of sufficient substrate supply in vitro makes pancreatic acinar cells susceptible to necrosis caused by ethanol and CCK in clinically relevant concentrations.

Severe hypertriglyceridemia and pancreatitis: presentation and management

PURPOSE OF REVIEW

Hypertriglyceridemia (HTG) is a well recognized cause of acute pancreatitis accounting for approximately up to 10% of all cases and even up to 50% of all cases in pregnancy. Both primary and secondary disorders of lipoprotein metabolism may be associated with hypertriglyceridemic pancreatitis (HTGP). The purpose of this review is to provide an overview of the current studies on presentation and management of HTGP.

RECENT FINDINGS/CONCLUSION

Hydrolysis of triglycerides by pancreatic lipase and formation of free fatty acids that induce inflammatory changes are postulated to account for the development of HTGP, yet the exact pathophysiology remains unclear. The clinical features of patients with HTGP are generally not different from patients with acute pancreatitis of other causes, and there is some evidence that HTGP is associated with a higher severity or a higher complication rate. There is no clear evidence as to which HTG patients will develop pancreatitis. Several studies have evaluated the effect of apheresis, the benefit of insulin and/or heparin treatment and the use of different antihyperlipidemic agents in HTGP. Dietary modifications resemble the key features in the long-term management of HTG. Whether HTG may cause chronic pancreatitis in the long-term follow-up remains controversial.

New insights into alcoholic pancreatitis and pancreatic cancer

Pancreatitis and pancreatic cancer represent two major diseases of the exocrine pancreas. Pancreatitis exhibits both acute and chronic manifestations. The commonest causes of acute pancreatitis are gallstones and alcohol abuse; the latter is also the predominant cause of chronic pancreatitis. Recent evidence indicates that endotoxinemia, which occurs in alcoholics due to increased gut permeability, may trigger overt necroinflammation of the pancreas in alcoholics and one that may also play a critical role in progression to chronic pancreatitis (acinar atrophy and fibrosis) via activation of pancreatic stellate cells (PSCs). Chronic pancreatitis is a major risk factor for the development of pancreatic cancer, which is the fourth leading cause of cancer-related deaths in humans. Increasing attention has been paid in recent years to the role of the stroma in pancreatic cancer progression. It is now well established that PSCs play a key role in the production of cancer stroma and that they interact closely with cancer cells to create a tumor facilitatory environment that stimulates local tumor growth and distant metastasis. This review summarizes recent advances in our understanding of the pathogenesis of alcoholic pancreatitis and pancreatic cancer, with particular reference to the central role played by PSCs in both diseases. An improved knowledge of PSC biology has the potential to provide an insight into pathways that may be therapeutically targeted to inhibit PSC activation, thereby inhibiting the development of fibrosis in chronic pancreatitis and interrupting stellate cell-cancer cell interactions so as to retard cancer progression.

ESPEN Guidelines on Parenteral Nutrition: pancreas

Assessment of the severity of acute pancreatitis (AP), together with the patient's nutritional status is crucial in the decision making process that determines the need for artificial nutrition. Both should be done on admission and at frequent intervals thereafter. The indication for nutritional support in AP is actual or anticipated inadequate oral intake for 5-7 days. This period may be shorter in those with pre-existing malnutrition. Substrate metabolism in severe AP is similar to that in severe sepsis or trauma. Parenteral amino acids, glucose and lipid infusion do not affect pancreatic secretion and function. If lipids are administered, serum triglycerides must be monitored regularly. The use of intravenous lipids as part of parenteral nutrition (PN) is safe and feasible when hypertriglyceridemia is avoided. PN is indicated only in those patients who are unable to tolerate targeted requirements by the enteral route. As rates of EN tolerance increase then volumes of PN should be decreased. When PN is administered, particular attention should be given to avoid overfeeding. When PN is indicated, a parenteral glutamine supplementation should be considered. In chronic pancreatitis PN may, on rare occasions, be indicated in patients with gastric outlet obstruction secondary to duodenal stenosis or those with complex fistulation, and in occasional malnourished patients prior to surgery.

Molecular mechanisms of pancreatitis: current opinion

Pancreatitis (necroinflammation of the pancreas) has both acute and chronic manifestations. Gallstones are the major cause of acute pancreatitis, whereas alcohol is associated with acute as well as chronic forms of the disease. Cases of true idiopathic pancreatitis are steadily diminishing as more genetic causes of the disease are discovered. The pathogenesis of acute pancreatitis has been extensively investigated over the past four decades; the general current consensus is that the injury is initiated within pancreatic acinar cells subsequent to premature intracellular activation of digestive enzymes. Repeated attacks of acute pancreatitis have the potential to evolve into chronic disease characterized by fibrosis and loss of pancreatic function. Our knowledge of the process of scarring has advanced considerably with the isolation and study of pancreatic stellate cells, now established as the key cells in pancreatic fibrogenesis. The present review summarizes recent developments in the field particularly with respect to the progress made in unraveling the molecular mechanisms of acute and chronic pancreatic injury secondary to gallstones, alcohol and genetic factors. It is anticipated that continued research in the area will lead to the identification and characterization of molecular pathways that may be therapeutically targeted to prevent/inhibit the initiation and progression of the disease.

Acute pancreatitis in a cohort of 129 patients referred for severe hypertriglyceridemia

OBJECTIVES

The aim of this study was to assess retrospectively the prevalence and the predictive factors of acute pancreatitis (AP) in a population of patients referred in our endocrinology department for evaluation of very high triglyceride (TG) levels.

METHODS

One hundred twenty-nine patients (119 with type IV phenotypes and 10 with type V phenotypes according to Fredrickson's classification) were referred to our hospital between 2000 and 2005.

RESULTS

Twenty-six subjects (20.2% of the population) presented with AP. This population was significantly younger at diagnosis of hyperlipidemia (32 vs 40 years, P < 0.001) and at age of investigation (43 vs 48 years, P = 0.05) and had maximum TG levels greater than the population without AP (44.7 vs 24.5, P < 0.001). Subjects of the third tertile of TG levels had a 4.0-fold increased risk (95% confidence interval, 1.3-12.3) of AP compared with the first tertile. Severe pancreatitis (need for intensive care, C-reactive protein >150 mg/L, or Balthazar score >C) was observed in 71.5% of the patients.

CONCLUSIONS

Twenty percent of patients with severe hypertriglyceridemia experience at least 1 attack of AP. Pancreatitis seems to occur in young patients at higher levels of TG than previously thought (85% of patients >30 g/L) and is associated with a severe clinical course.

Individual susceptibility to alcoholic pancreatitis

The observation that only a minority of heavy drinkers develop pancreatitis has prompted an intensive search for a trigger factor/cofactor/susceptibility factor that may precipitate a clinical attack. Putative susceptibility factors examined so far include diet, smoking, amount and type of alcohol consumed, the pattern of drinking and lipid intolerance. In addition, a range of inherited factors have been assessed including blood group antigens, human leukocyte antigen serotypes, alpha-1-antitrypsin phenotypes and several genotypes. The latter group comprises mutations/polymorphisms in genes related to alcohol-metabolizing enzymes, detoxifying enzymes, pancreatic digestive enzymes, pancreatic enzyme inhibitors, cystic fibrosis and cytokines. Disappointingly, despite this concerted research effort, no clear association has been established between the above factors and alcoholic pancreatitis. Experimentally, the secretagogue cholecystokinin (CCK) has been investigated as a candidate 'trigger' for alcoholic pancreatitis. However, the clinical relevance of CCK as a trigger factor has to be questioned, as it is difficult to envisage a situation in humans where abnormally high levels of CCK would be released into the circulation to trigger pancreatitis in alcoholics. In contrast, bacterial endotoxemia is a candidate cofactor that does have relevance to the clinical situation. Plasma lipopolysaccharide (LPS, an endotoxin) levels are significantly higher in drinkers (either after chronic alcohol intake or a single binge) compared to non-drinkers. We have recently shown that alcohol-fed animals challenged with otherwise innocuous doses of LPS exhibit significant pancreatic injury. Moreover, repeated LPS exposure in alcohol-fed rats leads to progressive injury to the gland characterized by significant pancreatic fibrosis. These studies support the concept that endotoxin may be an important factor in the initiation and progression of alcoholic pancreatitis. Scope remains for further studies examining proteins related to cellular anti-oxidant defenses, minor cystic fibrosis (CF) mutations and trans-heterozygosity involving a combination of mutations of different genes (such as CFTR alterations combined with SPINK1 or PRSS1 variants), as potential triggers of alcoholic pancreatitis.

Review of idiopathic pancreatitis

Recent advances in understanding of pancreatitis and advances in technology have uncovered the veils of idiopathic pancreatitis to a point where a thorough history and judicious use of diagnostic techniques elucidate the cause in over 80% of cases. This review examines the multitude of etiologies of what were once labeled idiopathic pancreatitis and provides the current evidence on each. This review begins with a background review of the current epidemiology of idiopathic pancreatitis prior to discussion of various etiologies. Etiologies of medications, infections, toxins, autoimmune disorders, vascular causes, and anatomic and functional causes are explored in detail. We conclude with management of true idiopathic pancreatitis and a summary of the various etiologic agents. Throughout this review, areas of controversies are highlighted.

Recurrent acute and chronic pancreatitis in two brothers with familial chylomicronemia syndrome

The chylomicronemia syndrome is well recognized as a rare etiologic factor of acute pancreatitis; however, whether hypertriglyceridemia can cause chronic pancreatitis (CP) remains unclear. We describe the long-time course of 2 brothers with the familial chylomicronemia syndrome caused by identical compound heterozygous mutations in the lipoprotein lipase (LPL) gene with markedly reduced LPL activity. Other etiologic factors were excluded, including mutations in the PRSS1, SPINK1, and CFTR gene. Although both brothers had recurrent acute pancreatitis and the same LPL genotype, CP became evident in only one patient. Progression to CP was associated with a more severe disease course. Thus, the chylomicronemia syndrome may cause CP in the absence of other known causative factors, and similar to alcoholic and hereditary CP, a more severe disease course is associated with disease progression.

Molecular mechanisms of alcoholic pancreatitis

Alcoholic pancreatitis is a major complication of alcohol abuse. Since only a minority of alcoholics develop pancreatitis, there has been a keen interest in identifying the factors that may confer individual susceptibility to the disease. Numerous possibilities have been evaluated including diet, drinking patterns and a range of inherited factors. However, at the present time, no susceptibility factor has been unequivocally identified. In contrast, considerable progress has been made with respect to the constant effects of alcohol on the pancreas. The molecular mechanisms of alcohol-induced pancreatic injury are being increasingly defined with an emphasis, in recent years, on the acinar cell itself as the principal site on ethanol-related damage. It has now been established that the acinar cell is capable of metabolizing alcohol and that the direct toxic effects of alcohol and/or its metabolites on acinar cells may predispose the gland to autodigestive injury in the presence of an appropriate triggering factor. A significant recent development relates to the characterization of pancreatic stellate cells, increasingly implicated in alcoholic pancreatic fibrosis. Here the current concepts regarding the mechanisms/pathways mediating alcohol-induced pancreatic injury are outlined.

Issues in hyperlipidemic pancreatitis

Hypertriglyceridemia (HTG) is a rare cause of pancreatitis. Pancreatitis secondary to HTG, presents typically as an episode of acute pancreatitis (AP) or recurrent AP, rarely as chronic pancreatitis. A serum triglyceride (TG) level of more than 1,000 to 2,000 mg/dL in patients with type I, IV, or V hyperlipidemia (Fredrickson's classification) is an identifiable risk factor. The typical clinical profile of hyperlipidemic pancreatitis (HLP) is a patient with a preexisting lipid abnormality along with the presence of a secondary factor (e.g., poorly controlled diabetes, alcohol use, or a medication) that can induce HTG. Less commonly, a patient with isolated hyperlipidemia (type V or I) without a precipitating factor presents with pancreatitis. Interestingly, serum pancreatic enzymes may be normal or only minimally elevated, even in the presence of severe pancreatitis diagnosed by imaging studies. The clinical course in HLP is not different from that of pancreatitis of other causes. Routine management of AP caused by hyperlipidemia should be similar to that of other causes. A thorough family history of lipid abnormalities should be obtained, and an attempt to identify secondary causes should be made. Reduction of TG levels to well below 1,000 mg/dL effectively prevents further episodes of pancreatitis. The mainstay of treatment includes dietary restriction of fat and lipid-lowering medications (mainly fibric acid derivatives). Experiences with plasmapheresis, lipid pheresis, and extracorporeal lipid elimination are limited.

Diabetic hypertriglyceridemia-induced acute pancreatitis masquerading as biliary pancreatitis

Diabetes mellitus has a profound effect on plasma lipid metabolism especially triglycerides. One complication of hypertriglyceridemia is acute pancreatitis. Here, we report a case of diabetic hypertriglyceridemia-induced recurrent acute pancreatitis that masquerades as biliary pancreatitis. Institution of insulin therapy caused a resolution of the hypertriglyceridemia and a cessation of the episodes of acute pancreatitis.

Polymorphism in alcohol-metabolizing enzymes, glutathione S-transferases and apolipoprotein E and susceptibility to alcohol-induced cirrhosis and chronic pancreatitis

BACKGROUND AND AIM

Susceptibility to organ damage induced by alcohol may be due to inherited variation (polymorphism) in ethanol-metabolizing enzymes, or to polymorphisms affecting free radical or lipid metabolism mediated by enzymes such as glutathione S-transferases and apolipoprotein E. The aim was to compare the genotype frequencies of alcohol dehydrogenase-2 (ADH2), ADH3, aldehyde dehydrogenase-2 (ALDH2), cytochrome P450-2E1 (CYP2E1), glutathione S-transferase-M1 (GSTM1), GSTT1, and apolipoprotein E in patients with alcoholic cirrhosis and alcoholic chronic pancreatitis to those in control groups.

PATIENTS AND METHODS

The case-control study was restricted to Caucasian adults: 57 with alcoholic cirrhosis, 71 with alcoholic chronic pancreatitis, 57 alcoholics without apparent organ damage and 200 healthy blood donors. Genotypes were determined by restriction fragment length polymorphism after amplification of genomic DNA by polymerase chain reaction.

RESULTS

The genotype ADH3*2/*2 was more frequent in patients with cirrhosis (40%) than blood donors (12%; OR 4.92, 95% CI 2.36-10.31) and patients with chronic pancreatitis (8%; OR 7.33, 95% CI 2.54-23.78) but was not significantly different from alcoholic controls (23%; OR 2.27, 95% CI 0.95-5.66). Patients with cirrhosis also had a higher frequency (P < 0.05) of ADH2*1/*1 (100%) than blood donors (92%) and those with chronic pancreatitis (93%). The frequencies of genotypes of ALDH2, CYP2E1, GSTM1, GSTT1 and apolipoprotein E were similar in all groups.

CONCLUSION

Alcoholic cirrhosis but not alcoholic chronic pancreatitis is associated with ADH3*2/*2 and perhaps with ADH2*1/*1. Both genes encode less active alcohol-metabolizing enzymes that may be associated with cirrhosis because of delayed formation of acetaldehyde (with higher intakes of alcohol), or diversion of alcohol metabolism through pathways other than ADH.

Nutritional and metabolic effects of alcoholism: their relationship with alcoholic liver disease

Excessive alcohol ingestion disturbs the metabolism of most nutrients. Although alcohol can lead to severe hypoglycemia, alcoholics are usually glucose intolerant, probably due to a inhibition of glucose-stimulated insulin secretion. Ethanol intake also leads to negative nitrogen balance and an increased protein turnover. Alcohol also alters lipid metabolism, causing a profound inhibition of lipolysis. Looking for an association between alcohol intake, nutrition, and alcoholic liver disease, we have observed a higher prevalence of subclinical histologic liver damage among obese alcoholics. Multivariate analysis in a large group of alcoholics has shown that obesity is an independent predictor of alcoholic liver disease. Other authors have reported that alcoholics with a history of obesity have a two to three times higher risk of having alcoholic liver disease than non-obese alcoholics. The possible explanation for this association is that the microsomal system, which plays an important pathogenic role in alcoholic liver disease, is induced in non-alcoholic obese subjects and alcoholics. Also, peripheral blood monocyte cells of obese alcoholics produce higher levels of interleukin-1, a cytokine that can contribute to liver damage. The ingestion of polyunsaturated fatty acids can also increase the damaging effects of alcohol on the liver, as has been demonstrated in rats subjected to continuous intragastric infusion of alcohol. Observations in human alcoholics have shown that liver damage is associated with a higher ratio of C:18:1/C:18:0 and a lower ratio of C:22:4/C:18:2 in liver lipids, consistent with an induction of delta 9 desaturase and an increased peroxidation of C:22:4.

Alcohol and the pancreas

Alcoholic pancreatitis may be one of the most serious adverse consequences of alcohol abuse. Its diagnosis, as it has for many years, depends primarily on clinical acumen in interpreting properly the symptoms and signs of abdominal distress, buttressed by elevated pancreatic enzymes (amylase and lipase). More recently, the use of computerized tomography (CT) in selected situations has been both of confirmatory and prognostic value. Severity of abnormality by CT correlates reasonably well with a variety of clinical-laboratory clusters (APACHE system, Ranson's criteria, etc.) and aids in therapy. The pathogenesis of alcoholic pancreatitis is not fully defined. The ultimate picture is one of tissue autolysis by activated proteolytic enzymes. The triggers for such activation, however, are still not known. They are represented by three main theories: (1) large duct obstruction and/or increased permeability relative to pancreatic secretion, (2) small duct obstruction due to proteinaceous precipitates, and (3) a direct toxic-metabolic effect of ethanol on pancreatic acinar cells. While not mutually exclusive, we favor the last hypothesis as being most consistent with the effects of ethanol on other organ systems. The direct effects of ethanol and/or its metabolites may be mediated, at least in part, via oxidative stress or the generation of fatty acid ethyl esters. Autolysis (regardless of proximate mechanism(s)) leads to inflammation likely mediated via release of various cytokines. It also should be appreciated that "acute" pancreatitis (the topic of this chapter) likely represents an acute process within a chronic pancreatic exposure and injury from alcoholic abuse. The key question of why pancreatitis develops in only a small number of alcohol abusers is not resolved. Therapy depends on the severity of alcoholic pancreatitis, which is defined by clinical-laboratory and often CT criteria. Mild pancreatitis usually resolves acutely with alcohol abstention and supportive therapy. Severe pancreatitis has a significant morbidity and mortality, mainly related to the degree of pancreatic necrosis and infection. It requires meticulous combined medical-surgical care.

Cystic fibrosis genotypes and alcoholic pancreatitis

Pancreatitis and pancreatic insufficiency are associated with both cystic fibrosis and alcoholism. The pathogenesis of alcoholic pancreatitis is unknown, but only a minority of alcoholics develop pancreatitis, and it has been suggested that a genetic predisposition may play a role in this disease. Two observations led to the hypothesis that this genetic predisposition could result from mutations in the cystic fibrosis gene. First, the prevalence of cystic fibrosis mutations in the Caucasian population (approximately 5%) is similar to the prevalence of pancreatitis among heavy drinkers. Second, in both diseases, pancreatic duct damage is a prominent feature and has been postulated to be the initial site of injury. Therefore, the aim of this study was to determine whether an increased frequency of mutations in the cystic fibrosis gene occurs in alcoholic pancreatitis. The 15 most common cystic fibrosis mutations in a Caucasian community were sought in 24 subjects with alcoholic pancreatitis. None were homozygous or heterozygous for these mutations. These findings suggest that cystic fibrosis mutations are not a major genetic factor predisposing to pancreatic injury in alcoholics.

Hyperlipidemia in acute pancreatitis. Cause or epiphenomenon?

Whether hyperlipidemia is a pre-existing metabolic disorder or a consequence of acute pancreatitis is still debated. Mild to moderate elevation of serum triglyceride levels are likely to be an epiphenomenon of the pancreatic disease. A marked hyperchylomicronemia and hypertrygliceridemia would be needed to trigger acute pancreatitis; a relevant defect in the lipid catabolism and clearance should therefore pre-exist. The aim of the present study was to investigate whether patients with acute pancreatitis and marked hyperlipidemia have an impaired clearance capacity of exogenous lipids, which would define the hyperlipidemia as a preexistent abnormality and therefore a potential cause of the pancreatic disease. With this aim, the kinetics of the removal of exogenous triglycerides from the circulation have been analyzed. Twenty patients with acute pancreatitis have been studied. Ten of them suffered from an episode of acute pancreatitis with marked hyperlipidemia (serum triglyceride levels > 20 mmol/L). Four to six months after recovery from the pancreatitis, a two-stage infusion of Intralipid 20% was carried out and the fractional removal rate (K2) and the maximal clearance capacity (K1) of exogenous triglycerides were calculated. At low infusion rates a first order kinetics for removal was observed, whereas at high infusion rates a zero order kinetics was operating. All patients with a previous attack of normolipidemic acute pancreatitis had normal K2 and K1 values. Five patients with previous hyperlipidemic acute pancreatitis had an abnormally low clearance capacity of exogenous triglycerides, whereas the remaining five had normal removal values. The present study provides new information in the association between hyperlipidemia and acute pancreatitis by showing that even a marked elevation of serum lipid levels should not be invariably considered as the etiological factor of the pancreatic disease, even if other potential causes are not evident.

Significant increase of blood alcohol by cimetidine after repetitive drinking of small alcohol doses

To assess effects of repetitive alcohol drinking and pre-existing first-pass metabolism on the cimetidine-induced increase in blood alcohol concentrations, 20 healthy men (aged 20 to 40) of varied ethnicity and consuming less than 60 g alcohol per week underwent baseline quantitation of first-pass metabolism of alcohol. This was followed by oral administration of 0.6 g/kg ethanol given postprandially in 3 to 4 drinks spread over 135 min, before and after cimetidine (400 mg twice a day for 7 days). Blood alcohol concentrations were determined by breath analysis. First-pass metabolism was quantified by applying Michaelis-Menten kinetics to blood alcohol curves after intravenous or oral administration of equal alcohol doses. At baseline, 15 subjects had a substantial first-pass metabolism (over one sixth of the dose); their alcohol levels increased with repeated doses with a mean peak of 27 +/- 3 mg/dl before and 39 +/- 5 after cimetidine (P < 0.01), an effect much greater and longer than after a single alcohol dose. Three subjects exceeded 50 mg/dl, the legal limit for driving in several countries. By contrast, in the five subjects with minimal first-pass metabolism, cimetidine did not increase alcohol levels. Thus, under conditions mimicking social drinking, cimetidine increased blood alcohol to concentrations known to impair psychomotor skills and they persisted at those levels over prolonged periods of time. In a minority of subjects, no such interaction was found, but their first-pass metabolism at baseline was absent or minimal and thus no inhibition by the drug was to be expected.