Blood concentrations of acetaldehyde during chlorpropamide-alcohol flush

Pharmacotherapy of type 2 diabetes mellitus: an update on drug-drug interactions

The incidence of type 2 diabetes mellitus is increasing rapidly, as are the associated co-morbidities. Consequently, it has become necessary for a diabetic patient to take multiple medications at the same time to delay progression of the disease. This can put patients at an increased risk of moderate to severe drug interactions, which may threaten patients' life or may deteriorate the quality of their life. Hence, managing drug-drug interactions is the cornerstone of anti-diabetic therapy. Most of the clinically important drug-drug interactions of anti-diabetic agents are related to their metabolic pathways, but drugs that compete for renal excretion or impair renal status can also play an important role. In this review, we have examined the clinical implications and underlying mechanisms of drugs that are likely to alter the pharmacologic response of or cause adverse events with antidiabetic drugs, and we have outlined safe and efficacious treatment modalities.

Facial skin temperature in chlorpropamide alcohol flush

Objective methods to study the chlorpropamide alcohol flush (CPAF) have been inadequate. Determination of blood acetaldehyde has proved to be a promising method, but the analysis is difficult and time-consuming. To measure the facial skin temperature is more handy. The results of these measurements can be presented as delta T (skin temperature increase), %T (per cent of maximum possible temperature rise) or delta MTCI (malar thermal circulation index) after calculations. The baseline skin temperature is accounted for in %T and delta MTCI. Blood acetaldehyde determinations and placebo-alcohol tests can be used to separate the CPAF reaction from alcohol flushing. Single dose CPAF tests including facial skin temperature measurements were performed in 133 type 2 (non-insulin dependent) diabetics. Facial flush was observed in 42.9%. The specificity and sensitivity of all three skin temperature methods were high: 88.2, 85.5, 96.1%, and 89.5, 86.0, 86.0%, respectively. Skin temperature measurement, whether expressed as delta T, %T or delta MTCI, provides a method to study CPAF with high accuracy.

Is habitual alcohol drinking associated with reduced electrophoretic DNA migration in peripheral blood leukocytes from ALDH2-deficient male Japanese?

Alcohol drinking-derived acetaldehyde is believed to cross-link DNA and induce sister chromatid exchanges in peripheral blood lymphocytes. However, little population data are available to illustrate effects of alcohol-derived acetaldehyde on DNA migration as assayed by the comet assay in peripheral lymphocytes. In the present study, we investigated lifestyle behaviours, including alcohol consumption, in 150 Japanese males by questionnaire, determined their aldehyde dehydrogenase 2 (ALDH2) family genotypes by polymerase chain reaction and measured the DNA migration in peripheral blood leukocytes by the alkaline comet assay. The results showed that habitual alcohol drinking is significantly negatively associated with DNA migration in peripheral blood leukocytes (r = -0.321, P = 0.005) of ALDH2-deficient, but not of ALDH2-proficient genotypes (r = 0.048, P = 0.683). The amount of pure alcohol consumed per time by the subjects showed a similar phenomenon (r = -0.257, P = 0.025 for the ALDH2-deficient, but r = -0.061, P = 0.606 for the ALDH2-proficient genotype). Further stepwise multiple regression analysis showed that alcohol drinking frequency was a significant predictor of DNA migration for subjects with ALDH2-deficient genotype, but not for subjects with ALDH2-proficient genotype. In summary, the present result suggests that frequent alcohol drinking is significantly associated with a reduced electrophoretic DNA migration in peripheral blood leukocytes from ALDH2-deficient male Japanese subjects.

Aldehyde-induced platelet aggregation

Formaldehyde, acetaldehyde, malondialdehyde, glutaraldehyde and paraldehyde, when added in vitro to platelet-rich plasma, generate a similar distinct platelet aggregation response which is dose dependent when measured with a manual visual microscopic technique and by computerized image analysis, 'computerized platelet aggregation analysis'. Light transmission aggregometry did not measure this aggregation in a reliable manner. The aggregating reaction was specific to the aldehyde group and was not seen when the aldehyde was replaced by an alcohol, ketone, or acetate group in the case of acetaldehyde. The maximal aggregating effect of these aldehydes was directly proportional to the number of aldehyde groups per molecule. Aggregation was found to require the presence of plasma, but not von Willebrand's factor.

The role of acetaldehyde in the actions of alcohol (update 2000)

BACKGROUND

Recent advances in the field of acetaldehyde (AcH) research have raised the need for a comprehensive review on the role of AcH in the actions of alcohol. This update is an attempt to summarize the available AcH research.

METHODS

The descriptive part of this article covers not only recent research but also the development of the field. Special emphasis is placed on mechanistic analyses, new hypotheses, and conclusions.

RESULTS

Elevated AcH during alcohol intoxication causes alcohol sensitivity, which involves vasodilation associated with increased skin temperature, subjective feelings of hotness and facial flushing, increased heart and respiration rate, lowered blood pressure, sensation of dry mouth or throat associated with bronchoconstriction and allergy reactions, nausea and headache, and also reinforcing reactions like euphoria. These effects seem to involve catecholamine, opiate peptide, prostaglandin, histamine, and/or kinin mechanisms. The contribution of AcH to the pathological consequences of chronic alcohol intake is well established for different forms of cancer in the digestive tract and the upper airways. AcH seems to play a role in the etiology of liver cirrhosis. AcH may have a role in other pathological developments, which include brain damage, cardiomyopathy, pancreatitis, and fetal alcohol syndrome. AcH creates both unpleasant aversive reactions that protect against excessive alcohol drinking and euphoric sensations that may reinforce alcohol drinking. The protective effect of AcH may be used in future treatments that involve gene therapy with or without liver transplantation.

CONCLUSIONS

AcH plays a role in most of the actions of alcohol. The individual variability in these AcH-mediated actions will depend on the genetic polymorphism, not only for the alcohol and AcH-metabolizing enzymes but also for the target sites for AcH actions. The subtle balance between aversive and reinforcing, protecting and promoting factors will determine the overall behavioral and pathological developments.

The role of acetaldehyde in the actions of alcohol (update 2000)

BACKGROUND

Recent advances in the field of acetaldehyde (AcH) research have raised the need for a comprehensive review on the role of AcH in the actions of alcohol. This update is an attempt to summarize the available AcH research.

METHODS

The descriptive part of this article covers not only recent research but also the development of the field. Special emphasis is placed on mechanistic analyses, new hypotheses, and conclusions.

RESULTS

Elevated AcH during alcohol intoxication causes alcohol sensitivity, which involves vasodilation associated with increased skin temperature, subjective feelings of hotness and facial flushing, increased heart and respiration rate, lowered blood pressure, sensation of dry mouth or throat associated with bronchoconstriction and allergy reactions, nausea and headache, and also reinforcing reactions like euphoria. These effects seem to involve catecholamine, opiate peptide, prostaglandin, histamine, and/or kinin mechanisms. The contribution of AcH to the pathological consequences of chronic alcohol intake is well established for different forms of cancer in the digestive tract and the upper airways. AcH seems to play a role in the etiology of liver cirrhosis. AcH may have a role in other pathological developments, which include brain damage, cardiomyopathy, pancreatitis, and fetal alcohol syndrome. AcH creates both unpleasant aversive reactions that protect against excessive alcohol drinking and euphoric sensations that may reinforce alcohol drinking. The protective effect of AcH may be used in future treatments that involve gene therapy with or without liver transplantation.

CONCLUSIONS

AcH plays a role in most of the actions of alcohol. The individual variability in these AcH-mediated actions will depend on the genetic polymorphism, not only for the alcohol and AcH-metabolizing enzymes but also for the target sites for AcH actions. The subtle balance between aversive and reinforcing, protecting and promoting factors will determine the overall behavioral and pathological developments.

Failure of glutathione and cysteine prodrugs to block the chlorpropamide-induced inhibition of aldehyde dehydrogenase in vivo

Augmentation of cellular L-cysteine or glutathione (GSH) levels in vivo by the administration of prodrugs of L-cysteine or GSH, viz. 2(R,S)-methylthiazolidine-4(R)-carboxylic acid (MTCA), 2(R,S)-D-ribo-(1',2',3',4'-tetrahydroxybutyl)thiazolidine-4(R)-car boxylic acid (RibCys) and GSH monoethyl ester (GSH-OEt), did not block the inhibition of aldehyde dehydrogenase (AlDH) by chlorpropamide (CP) or N1-ethylchlorpropamide (N1-EtCP), as shown by their inability to protect AlDH and thereby prevent the elevation of blood acetaldehyde (AcH) in ethanol-treated rats. Since the formation of an alkylcarbamoylating species by conjugation of n-propylisocyanate, a potential metabolite of CP or N1-EtCP, with GSH or L-cysteine is possible, intervention by GSH or cysteine may not produce a detoxified product. Evaluation of the two products that could theoretically be produced in vivo, viz. S-(n-propylcarbamoyl)-L-cysteine and S-(n-propylcarbamoyl)-GSH, indicated that these compounds inhibit rather than spare AlDH in rats. Indeed, the latter were as effective as N1-EtCP, a direct acting inhibitor of AlDH, and all three were better inhibitors of AlDH in vivo than CP itself. Thus, formation of S-conjugates of the active CP metabolite produced in vivo may not be a detoxication process, but may in fact represent redistribution of a transportable form of this highly reactive metabolite.

Alcohol and treatment of diabetes

The effects of alcohol on diabetic patients controlled on insulin are reviewed and the associated risks of hypoglycaemia, insulin resistance and ketosis are commented on. The impact of alcohol intake in patients with maturity onset diabetes is also considered and potential interactions with oral hypoglycaemic agents highlighted.

A nonhypoglycemic chlorpropamide analog that inhibits aldehyde dehydrogenase

Chlorpropamide (CP), a sulfonylurea-type oral hypoglycemic agent, is known to provoke a flushing reaction reminiscent of the disulfiram-ethanol reaction in certain individuals. This is manifested in rodents by an increase in blood acetaldehyde levels after ethanol administration. When the sulfonamide N1-nitrogen of CP was substituted with an ethyl group, the product, N1-ethylchlorpropamide, was found to be three times as active as CP in raising ethanol-derived blood acetaldehyde. However, whereas CP lowered fasting blood glucose in rats measured over 6 h, N1-ethylchlorpropamide was devoid of hypoglycemic activity, suggesting that the latter might be potentially useful as an alcohol deterrent agent.

Adverse cardiovascular effects of sulphonylurea drugs. Clinical significance

Sulphonylureas are widely used in the treatment of diabetes mellitus. Since the publication of the University Groups Diabetes Program (UGDP) results the discussion on their possible cardiovascular side effects has been lively and sometimes even passionate. The initial UGDP findings about the adverse effects of tolbutamide on the cardiovascular system have been criticised, particularly for shortcomings in the study design. The results of other epidemiological studies of the sulphonylurea effects on cardiovascular morbidity and mortality published this far have been contradictory. This is understandable because the factors involved are very complex. Most of these studies have used tolbutamide only, and the findings cannot necessarily be directly extrapolated to other sulphonylureas. Only properly performed prospective studies may provide further information on this issue. High concentrations of several sulphonylureas may have inotropic effects on heart muscle in in vitro animal models, but human studies performed in vivo do not support the view of clinically significant inotropy for sulphonylureas. High concentrations of tolbutamide or glibenclamide (glyburide) may affect the myocardial metabolism in isolated organs, but the possible clinical significance of these findings remains unknown. Some epidemiological and experimental studies have associated oral antidiabetic treatment with the occurrence of cardiac arrhythmias or increased digitalis toxicity. Only a few results are available, and there may be differences between the sulphonylureas in this respect. Antiaggregatory properties have been postulated for some sulphonylureas. Gliclazide, in particular, has been studied, but some other compounds of this class have also been effective in short term studies. If confirmed, these effects on haemostasis would be noteworthy. The sulphonylurea effects on serum lipids, especially on HDL-cholesterol, have been discussed widely during the last few years. Decreases in HDL-cholesterol concentrations were suggested to be associated with sulphonylurea therapy. However, these findings were not confirmed in recent cross-sectional and longitudinal studies performed with different sulphonylureas. Chlorpropamide, and to a lesser extent tolbutamide, may cause dilutional hyponatraemia and aggravate existing heart failure. Glibenclamide may increase the clearance of water in the kidney.

Effect of acetaldehyde on rat platelet aggregation in vivo and in vitro

The effect of acetaldehyde on primary hemostasis and platelet aggregation was studied in vivo and in vitro in the rat. Acetaldehyde was found in circulation following ethanol intoxication or was present after direct i.v. injection. In vitro, acetaldehyde was added to whole blood or platelet plasma suspension. Bleeding time and blood loss were increased upon ethanol intoxication and immediately after i.v. infusion of acetaldehyde. The intrinsic coagulation system, assayed by APT-time, was unaffected. In vivo, ADP and collagen-induced platelet aggregation was inhibited upon the presence of acetaldehyde. In vitro, inhibition of platelet aggregation was observed when acetaldehyde was added to blood, while the addition of the compound to plasma did not affect platelet function.

Genetic and metabolic risk factors for the development of late complications in type I (insulin-dependent) diabetes

The genetic background seems to be involved in the development of type I diabetes and it might also be involved in the development of diabetic complications, but studies carried out so far have yielded conflicting results. The aim of this study was to evaluate the influence of some genetic markers and metabolic factors in the development of late diabetic complications. One hundred and twenty-seven patients (69 males, 58 females) with type I diabetes were evaluated for ABO and Rh blood groups, chlorpropamide alcohol flush (CPAF) and acetylator phenotype (AP) as well as for life-habits (smoking, alcohol use, diet and drug compliance), metabolic indexes (M-value, HbA1, cholesterol and triglyceride levels) and late complications of diabetes [coronary heart disease (CHD), arterial hypertension (AH), retinopathy and nephropathy]. Diabetic patients were more frequently fast acetylators and CPAF positive than controls and CPAF was more frequent among females than among males. None of the genetic markers used in this study appeared as a risk factor for the development of diabetic complications. At multiple logistic analysis different risk factors appeared for each microangiopathic complication. For retinopathy: female sex, duration of disease and triglyceride levels; for nephropathy: male sex, cholesterol levels and hypertension. These risk factors have already been recognized in previous studies, while the genetic markers evaluated in our study do not identify a greater or smaller risk for the development of late complications.

Association between chlorpropamide-alcohol flushing and fast acetylator phenotype in type I and type II diabetes

Different prevalences of chlorpropamide alcohol flushing (CPAF) have been reported by different authors in either type I or type II diabetics or in normal subjects and this could be due to different methodological approaches or to different criteria of evaluation of CPAF. Previous studies in small series of patients have also suggested the existence of an association between type I diabetes and the fast acetylator phenotype (AP). The first aim of this study was to find reliable criteria for the assessment of CPAF. The second was to evaluate the prevalence of CPAF and of AP in a large series of type I and type II diabetics; and the third was to evaluate possible associations of CPAF and AP. AP and CPAF were evaluated separately in 256 diabetics (110 with type I and 146 with type II diabetes) and in 183 diabetics (74 with type I and 109 with type II diabetes), respectively. In 156 of these subjects, the two markers were evaluated together. The occurrence of CPAF was studied by subjective and objective assessment and by thermographic recording; CPAF was quantified by the differential value of skin temperature increase [delta T(C-P)] and by the value of differential speed of ascent, expressed in angle-degrees [delta a(C-P)], after treatment with placebo and with chlorpropamide. The fast AP was more frequent in type I than in type II diabetics, was not related to family history of diabetes, sex of the patients, age at onset and duration of diabetes or metabolic control. The most reliable assessment of CPAF was represented by thermographic recording of speed of ascent of skin temperature. CPAF was more frequent in females than in males, more frequent in diabetics than in healthy controls, similarly frequent in type I and in type II diabetes and showed no relationship with family history of diabetes, age at onset, duration of diabetes or metabolic control. An association between fast AP and CPAF was found in type II, but not in type I diabetics: fast acetylators were more frequently CPAF-positive, while slow acetylators were more frequently CPAF-negative. In addition, a linear relationship was found between rate of acetylation and speed of ascent of facial skin temperature after chlorpropamide and alcohol in type II diabetics, not in type I diabetics. The meaning of this association is not clear and deserves further investigations.

Effect of tolbutamide and chlorpropamide on acetaldehyde metabolism in two inbred strains of mice

The mechanisms by which chlorpropamide and tolbutamide disrupt acetaldehyde metabolism were studied in C57BL and DBA mice. Acute po administration of varying doses of tolbutamide or chlorpropamide 2.5 hr before a 3.0 g/kg ip dose of ethanol to C57BL and DBA mice resulted in significant elevations of blood acetaldehyde when measured 2.5 hr after ethanol dosing. Dose-response analysis revealed a significant (p less than .05) difference in ED50 values for the elevated blood acetaldehyde response to tolbutamide in DBA (60 mg/kg) and C57BL (100 mg/kg) mice. The ED50 value for potentiation by chlorpropamide of blood acetaldehyde concentration was similar (23 to 32 mg/kg) in both inbred strains. At higher doses of chlorpropamide, DBA mice displayed elevations of blood acetaldehyde nearly threefold greater than those measured in C57BL mice treated identically. Measurements of aldehyde dehydrogenase (ALDH) in hepatic subcellular fractions, obtained from both inbred strains treated with 100 mg/kg tolbutamide or chlorpropamide prior to a 3.0 g/kg dose of ethanol, revealed a 50 to 80% inhibition of the low-Km ALDH present in mitochondria. Chlorpropamide and tolbutamide did not inhibit ALDH in vitro, suggesting that metabolites of these hypoglycemic agents may be responsible for the genotypic-dependent alterations in in vivo acetaldehyde oxidation.

Erythrocyte aldehyde dehydrogenase and disulfiram-like side effects of hypoglycemics and antianginals

Disulfiram-like responses to various drug therapies are caused by elevated ethnol-derived blood acetaldehyde concentrations resulting from drug-induced inhibition of aldehyde dehydrogenase enzymes. We have found that the nitrate ester antianginal drugs, isosorbide dinitrate and nitroglycerin, are potent inhibitors of human erythrocyte aldehyde dehydrogenase. To further characterize this drug-induced enzyme inhibition, erythrocyte aldehyde dehydrogenase activities were measured in patients undergoing therapy with nitrate ester antianginals (isosorbide dinitrate and nitroglycerin) and sulfonylurea hypoglycemics (chlorpropamide and tolazamide). The erythrocyte enzyme was decreased by approximately 25% in sulfonylurea-treated patients, whereas in the nitrate ester-treated patients, an 88% inhibition was observed. The minimal enzyme inhibition in the sulfonylurea-treated group was unexpected because these therapies have well-documented disulfiram-like side effects. This weak inhibition contrasted with the severe inhibition observed in the nitrate ester-treated group where the disulfiram-like side effects are not considered a serious clinical problem. This apparent anomaly was attributed to differences in inhibition of the erythrocyte and liver aldehyde dehydrogenase by the parent drugs and their hepatic metabolites.

Roles of chlorpropamide, alcohol and acetaldehyde in determining the chlorpropamide-alcohol flush

The value and reproducibility of the chlorpropamide-alcohol flush (CPAF) have been questioned, and objective measures of the test are required. Recording of facial skin temperature, measurement of chlorpropamide, ethanol and acetaldehyde concentrations have been proposed for this purpose. The present study was designed to evaluate the relative contributions of these variables in determining CPAF. Twenty-one Type 2 (non-insulin-dependent) diabetic patients (11 CPAF-positive and 10 CPAF-negative according to previous tests with standard amounts of alcohol and chlorpropamide) were investigated in a random fashion with either chlorpropamide or placebo given on three subsequent evenings before a two-step alcohol challenge with increasing body-weight-matched amounts of alcohol. Higher rises in facial skin temperature and heart rate, higher flush-score and higher acetaldehyde levels resulted from chlorpropamide therapy than followed placebo. After smaller alcohol challenges (with chlorpropamide pretreatment) there were positive intercorrelations between flush-score, rise in facial skin temperature, and plasma concentrations of chlorpropamide and blood acetaldehyde. The increased alcohol dose abolished most of these correlations and a minimum temperature rise of 1.8 degrees C appeared in all but two subjects regardless of previous CPAF classification. During the current experimental conditions, the previously-classified CPAF-positive and CPAF-negative patients did not differ with respect to flush-score, rise in skin temperature, heart rate, blood acetaldehyde or ethanol concentrations, whereas they differed with respect to chlorpropamide concentrations. The present results support the view that CPAF is associated with elevated blood acetaldehyde levels due to inhibition of aldehyde dehydrogenase by chlorpropamide.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidemiological study of prevalence of chlorpropamide alcohol flushing in insulin dependent diabetics, non-insulin dependent diabetics, and non-diabetics

An epidemiological study was carried out to compare the prevalence of facial flushing in non-diabetics, patients with insulin dependent diabetes, and patients with non-insulin dependent diabetes in response to 40 ml sherry taken 12 hours after 250 mg chlorpropamide or placebo, administered double blind in randomised order. A flush after chlorpropamide but not placebo was reported by 6.2% of non-diabetics (17/273), 9.7% of insulin-dependent diabetics (14/145), and 10.5% of non-insulin dependent diabetics (25/239), excluding those receiving long term chlorpropamide treatment. The differences were not significant. This response was unrelated to age, sex, body mass index, and family history of diabetes in all three groups. Patients taking long term chlorpropamide, however, showed a significantly (p less than 0.01) higher prevalence of flushing after both chlorpropamide and placebo (56.3%; 9/16) compared with the rest of the non-insulin dependent diabetics (16.7%; 40/239), the insulin dependent diabetics (6.9%; 10/145), and the non-diabetics (5.9%; 16/273). Patients receiving long term chlorpropamide would be expected to flush with sherry after a placebo tablet because of therapeutic plasma concentrations of the drug. It is concluded that there is no evidence of an increased prevalence of chlorpropamide alcohol flushing in response to the single challenge test in non-insulin dependent diabetics compared with insulin dependent diabetics and non-diabetics except in selected patients taking chlorpropamide long term. This study does not support the hypothesis that the chlorpropamide alcohol flush is a specific marker for a subtype of non-insulin dependent diabetes.

Chlorpropamide-ethanol induced met-enkephalin secretion in dogs: release mechanisms and biochemical characterisation

Circulating met-enkephalin-like immunoreactivity (MLI) rises in man after chlorpropamide and ethanol although the origin and molecular forms of circulating MLI are not well defined. We have studied the response to oral ethanol in conscious and anaesthetised dogs pretreated with chlorpropamide. In conscious dogs MLI rose from a basal level of 29 +/- 7 pg/ml to a peak of 55 +/- 14 pg/ml 10 min after ethanol (P less than 0.001). In anaesthetised animals, following ethanol, plasma MLI rose in caval (35 +/- 6 pg/ml to a peak of 70 +/- 10 pg/ml), in portal (28 +/- 6 pg/ml to 51 +/- 6 pg/ml) and in adrenal blood (897 +/- 316 pg/ml to 1483 +/- 298 pg/ml; P less than 0.001). Biogel P-4 chromatography of caval and portal basal plasma showed 87% of MLI measured coeluted with the synthetic pentapeptide, while chromatography of peak plasma showed that only 65% coeluted with the pentapeptide and the remaining 35% was of larger molecular size. Sephadex G75 chromatography of adrenal vein plasma revealed three peaks of MLI of differing molecular sizes (8 k = 69.7%; 3-5 k = 12.1% and the pentapeptide = 18.2%). Treatment of the column fractions with trypsin and carboxypeptidase B resulted in the generation of new MLI with peaks of approximate molecular sizes 31 k (10.4%), and 18 k (37.1%) in addition to 8 k (40.0%), 3-5 k (5.0%) and the pentapeptide (7.5%). Acetaldehyde involvement in MLI release was investigated. Following acetaldehyde infusion, plasma MLI rose both in caval (35 +/- 9 pg/ml to 86 +/- 8 pg/ml) and adrenal vein (417 +/- 121 pg/ml to 1768 +/- 433 pg/ml) bloods. Thus we have established an animal model which enables further study of the mechanisms of MLI release and characterisation of the molecular forms. The adrenal medulla, unlike the gut, may be an important source of circulating met-enkephalin and acetaldehyde formation an essential intrinsic component of chlorpropamide-ethanol induced met-enkephalin release.

Elimination of artifactual acetaldehyde in the measurement of human blood acetaldehyde by the use of polyethylene glycol and sodium azide: normal blood acetaldehyde levels in the dog and human after ethanol

A new procedure is described for the preparation of human blood samples for analysis of acetaldehyde and ethanol by head space gas chromatography. High concentrations of polyethylene glycol were used to remove the hemoglobin and approximately 50% of the plasma protein. Artifactual formation of acetaldehyde from ethanol was inhibited by sodium azide. Using this method, no artifactual acetaldehyde was detectable in human, dog, sheep, and rat blood when spiked with ethanol in final concentrations of 65 mM. The recovery of added acetaldehyde was approximately 80% for human dog, and sheep blood, whereas it was only 30% for rat blood. Following ethanol administration, acetaldehyde levels were determined in blood taken from the pulmonary artery and descending aorta of the dog and human, and also from the hepatic vein of the latter. The relative blood acetaldehyde concentrations at these sites were hepatic vein greater than pulmonary artery greater than descending aorta.

Assay of blood and tissue aldehydes by HPLC analysis of their 2,4-dinitrophenylhydrazine adducts

A new method for the assay of blood and tissue acetaldehyde is described. Samples are reacted with a methanolic solution of 2,4-dinitrophenylhydrazine (DNP) and the DNP-aldehyde adducts extracted into CHCl3. DNP-[14C]formaldehyde is added as internal standard. The CHCl3 extracts are washed with HCl and H2O and purified by aluminium oxide chromatography. The eluate is dried down, re-dissolved in methanol and subjected to quantitative analysis by HPLC. The acetaldehyde adduct was identified by co-chromatography with the authentic derivative and by mass spectrometry. Recoveries of added acetaldehyde were 85% and addition of 20 mmol ethanol to the sample gave no apparent increment in acetaldehyde content. This technique is suitable for assessment of acetaldehyde levels in clinical and experimental studies of ethanol metabolism.

Characterization of the chlorpropamide-alcohol-flush in patients with type 1 and type 2 diabetes

The aim of the present paper was to evaluate the prevalence of the chlorpropamide-alcohol-flush (CPAF) in patients with type 2 and with type 1 diabetes. Ninety-seven patients with type 2 diabetes and 33 with type 1 diabetes drank 40 ml vermouth 12 h after placebo and again 12 h after 1 tablet of chlorpropamide (250 mg) or 12 h after the last of repeated administrations of chlorpropamide (250 mg b.i.d. for 2 days). Skin temperature was recorded in all patients by a thermocouple probe connected to the left cheek. In 47 patients serum concentrations of chlorpropamide and of its metabolite CBSU were also determined. The prevalence of CPAF was similar in type 1 and type 2 diabetes, was greater in women than in men, and was significantly greater after repeated administrations than after one single administration of chlorpropamide. The increase of skin temperature during a 30-min period was significantly higher in patients with CPAF than in patients without CPAF. Serum concentrations of chlorpropamide and of its metabolite CBSU were more elevated after 4 than after 1 tablet of chlorpropamide, but were not significantly different in patients with and without CPAF. These data indicate that both genetic factors and the amount of chlorpropamide used affect the appearance of CPAF. To assess the possible role of serotonin and of dopamine in the CPAF, some patients with CPAF were tested again after treatment with metergoline, an antiserotonin agent, or with bromocriptine, a dopamine-agonist. Neither drug influenced the CPAF, indicating that the two neurotransmitters are not involved in the CPAF.

Clinical pathology of alcohol

There is good though not conclusive evidence that a small to modest average daily intake of alcohol--that is, 20-30 g/day is associated with increased longevity due mainly to a reduction in death from cardiovascular disease. Larger average daily alcohol intakes--especially those in excess of 60 g/day for men and 40 g/day for women--are associated with gradually increasing morbidity and mortality rates from a variety of diseases. Alcohol may be unrecognised as the cause of somatic disease, which can occur without overt psychosocial evidence of alcohol abuse, unless the index of suspicion is high and a thorough drink history obtained. Laboratory tests for the detection and/or confirmation of alcohol abuse are useful but subject to serious limitations being neither as sensitive nor specific as sometimes believed. The value of random blood and/or breath alcohol measurements, in outpatients, as an aid to diagnosis of alcohol-induced organic disease is probably not sufficiently appreciated and, though relatively insensitive, is highly specific.

Chlorpropamide-alcohol flushing and plasma chlorpropamide concentrations in diabetic patients on maintenance chlorpropamide therapy

Forty-three diabetic patients on maintenance chlorpropamide (100-750 mg daily) drank 0.2 ml/kg 90% ethanol after equilibration in a room controlled at 20 degrees C. Twenty-five patients had already noted marked alcohol flushing since starting chlorpropamide therapy (group A), while 13 had not observed this (group B). The remainder were teetotal or unsure of their reaction. Cheek temperature rise correlated with plasma chlorpropamide concentration (r = 0.6, p less than 0.001) in all patients and was inversely related to basal cheek temperature (r = -0.35, p less than 0.02). Plasma chlorpropamide correlated with daily chlorpropamide dose (r = 0.8, p less than 0.001) but not with basal cheek temperature. The correlation between chlorpropamide level and cheek temperature rise was strengthened on analysis of group A alone (r = 0.7, p less than 0.001) and absent in group B (r = 0.2, p greater than 0.3) who tended to have lower chlorpropamide levels and cheek temperature rise than group A.

Human blood acetaldehyde concentration during ethanol oxidation (update 1982)

A wide variety of levels of human blood acetaldehyde have been reported in the past. During the last few years, however, it has become increasingly evident that most, if not all, of the previously observed acetaldehyde concentrations during normal (i.e., no deficiency in, or inhibition of, aldehyde dehydrogenase activity) ethanol oxidation merely reflected artefactual acetaldehyde formed during the analytical procedures. The artefactual acetaldehyde formation, which occurs mainly during blood protein precipitation, is effectively minimized by the recently improved PCA method in which blood is immediately mixed with a perchloric acid-saline solution, and by the semicarbazide method in which blood is treated with a fresh isotonic semicarbazide solution before removal of the plasma. Nevertheless, a procedure involving control blood with ethanol added should be employed to control for any artefactual acetaldehyde still produced. Based on the improved analytical procedures, no detectable acetaldehyde was found in the venous blood of Caucasian subjects after acute ethanol intake.

Chlorpropamide-alcohol flushing, aldehyde dehydrogenase activity, and diabetic complications

Many diabetics who take chlorpropamide (a sulphonylurea compound) experience facial flushing after drinking even small amounts of alcohol. These flushers have a noticeably lower prevalence of late complications of diabetes (microangiopathy, macroangiopathy, and neuropathy) than non-flushers. This flush reaction is accompanied by increased blood acetaldehyde concentrations, suggesting an inhibition of aldehyde dehydrogenase activity. In the present study the activity of this enzyme in erythrocytes was assessed in the absence of chlorpropamide. Erythrocyte homogenates obtained from flushers and non-flushers were incubated with acetaldehyde and the rate of metabolism studies. Flushers eliminated acetaldehyde more slowly at a low range of concentrations (0--30 mumol/l), suggesting a difference in aldehyde dehydrogenase activity. Further studies are needed to clarify the role of this enzyme in the pathogenesis of diabetic complications.