Tolerability and Safety of a Novel Ketogenic Ester, Bis-Hexanoyl (R)-1,3-Butanediol: A Randomized Controlled Trial in Healthy Adults

Nutritional ketosis is a state of mildly elevated blood ketone concentrations resulting from dietary changes (e.g., fasting or reduced carbohydrate intake) or exogenous ketone consumption. In this study, we determined the tolerability and safety of a novel exogenous ketone diester, bis-hexanoyl-(R)-1,3-butanediol (BH-BD), in a 28-day, randomized, double-blind, placebo-controlled, parallel trial (NCT04707989). Healthy adults (n = 59, mean (SD), age: 42.8 (13.4) y, body mass index: 27.8 (3.9) kg/m2) were randomized to consume a beverage containing 12.5 g (Days 0-7) and 25 g (Days 7-28) of BH-BD or a taste-matched placebo daily with breakfast. Tolerability, stimulation, and sedation were assessed daily by standardized questionnaires, and blood and urine samples were collected at Days 0, 7, 14, and 28 for safety assessment. There were no differences in at-home composite systemic and gastrointestinal tolerability scores between BH-BD and placebo at any time in the study, or in acute tolerability measured 1-h post-consumption in-clinic. Weekly at-home composite tolerability scores did not change when BH-BD servings were doubled. At-home scores for stimulation and sedation did not differ between groups. BH-BD significantly increased blood ketone concentrations 1-h post-consumption. No clinically meaningful changes in safety measures including vital signs and clinical laboratory measurements were detected within or between groups. These results support the overall tolerability and safety of consumption of up to 25 g/day BH-BD.

Exogenous Ketone Supplements Improved Motor Performance in Preclinical Rodent Models

Nutritional ketosis has been proven effective for neurometabolic conditions and disorders linked to metabolic dysregulation. While inducing nutritional ketosis, ketogenic diet (KD) can improve motor performance in the context of certain disease states, but it is unknown whether exogenous ketone supplements—alternatives to KDs—may have similar effects. Therefore, we investigated the effect of ketone supplements on motor performance, using accelerating rotarod test and on postexercise blood glucose and R-beta-hydroxybutyrate (R-βHB) levels in rodent models with and without pathology. The effect of KD, butanediol (BD), ketone-ester (KE), ketone-salt (KS), and their combination (KE + KS: KEKS) or mixtures with medium chain triglyceride (MCT) (KE + MCT: KEMCT; KS + MCT: KSMCT) was tested in Sprague-Dawley (SPD) and WAG/Rij (WR) rats and in GLUT-1 Deficiency Syndrome (G1D) mice. Motor performance was enhanced by KEMCT acutely, KE and KS subchronically in SPD rats, by KEKS and KEMCT groups in WR rats, and by KE chronically in G1D mice. We demonstrated that exogenous ketone supplementation improved motor performance to various degrees in rodent models, while effectively elevated R-βHB and in some cases offsets postexercise blood glucose elevations. Our results suggest that improvement of motor performance varies depending on the strain of rodents, specific ketone formulation, age, and exposure frequency.

Development of a physiologically based toxicokinetic model for butadiene and four major metabolites in humans: Global sensitivity analysis for experimental design issues

1,3-Butadiene (BD) is metabolized in humans and rodents to mutagenic and carcinogenic species. Our previous work has focused on developing a physiologically based toxicokinetic (PBTK) model for BD to estimate its metabolic rate to 1,2-epoxy-3-butene (EB), using exhaled breath BD concentrations in human volunteers exposed by inhalation. In this paper, we extend our BD model to describe the kinetics of its four major metabolites EB, 1,2:3,4-diepoxybutane (DEB), 3-butene-1,2-diol (BDD), and 3,4-epoxy-1,2-butanediol (EBD), and to test whether the extended model and experimental data (to be collected for BD and metabolites in humans) are together adequate to estimate the metabolic rate constants of each of the above chemicals. Global sensitivity analyses (GSA) were conducted to evaluate the relative importance of the model parameters on model outputs during the 20min of exposure and the 40min after exposure ended. All model parameters were studied together with various potentially measurable model outputs: concentrations of BD and EB in exhaled air, concentrations of BD and all metabolites in venous blood, and cumulated amounts of urinary metabolites excreted within 24h. Our results show that pulmonary absorption of BD and subsequent distribution and metabolism in the well-perfused tissues compartment are the critical processes in the toxicokinetics of BD and metabolites. In particular, three parameters influence numerous outputs: the blood:air partition coefficient for BD, the metabolic rate of BD to EB, and the volume of the well-perfused tissues. Other influential parameters include other metabolic rates, some partition coefficients, and parameters driving the gas exchanges (in particular, for BD outputs). GSA shows that the impact of the metabolic rate of BD to EB on the BD concentrations in exhaled air is greatly increased if a few of the model's important parameters (such as the blood:air partition coefficient for BD) are measured experimentally. GSA also shows that all the transformation pathways described in the PBTK model may not be estimable if only data on the studied outputs are collected, and that data on a specific output for a chemical may not inform all the transformations involving that chemical.

GC/MS profiling of gamma-hydroxybutyrate and precursors in various animal tissues using automatic solid-phase extraction. Preliminary investigations of its potential interest in postmortem interval determination

To quantify gamma-hydroxybutyrate (GHB) and its physiological metabolites, gamma-aminobutyric acid (GABA), 1,4-butanediol (1,4-BD), and gamma-butyrolactone (GBL) in various animal tissues (kidney, muscle, heart, liver, blood, brain cortex, thalamus, hypothalamus, hippocampus, or pons), an original gas chromatographic/mass spectrometric method with a automated solid-phase extraction by Oasis MCX cartridges on a Gilson Aspec Xli was developed. Using such apparatus allowed the limit of detection (LOD) of target compounds to be significantly lowered (LOD: 0.027, 0.025, and 5.7 microg/mL for GHB, 1,4-BD, and GABA, respectively, in 200 microL or microg of sample). After validation of each analytical step, the satisfactory performances of the apparatus in conjunction with the rapidity and ease of the extraction step make it suitable for simultaneous assay of GHB, 1,4-BD, GBL, and GABA. The method was used to test the correlation between GHB levels in tissues obtained at different times after death of male Sprague-Dawley rats and the postmortem interval. Preliminary results show a linear increase of GHB levels in relation to time of death in thoracic blood and central nervous system of animals kept at 15 and 20 degrees C.

Intoxication due to 1,4-butanediol

We report a case of intoxication resulting from the ingestion of a liquid, sold in the illicit market as "liquid ecstasy," which was found to contain 1,4-butanediol, a metabolic precursor of gamma-hydroxybutiric acid (GHB). Identification of the substance in the liquid was performed by gas chromatography-mass spectrometry (GC-MS). The toxicological analysis of blood, urine and gastric content of the victim was performed by immunoassay and gas chromatography with nitrogen-phosphorus detection as screening techniques and by means of GC-MS for confirmation and quantitation of 1,4-butanediol and GHB. The following drug concentrations were found: 82 microg/ml (blood), 401 microg/ml (urine) and 7.4 microg/ml (gastric content) for 1,4-butanediol and 103 microg/ml (blood), 430.0 microg/ml (urine) for GHB. In addition to these, other drugs detected and their blood concentration found in this case were methylenedioxymethylamphetamine (MDMA) 0.23 microg/ml and its metabolite methylenedioxyphenylamphetamine (MDA) 0.10 microg/ml. In the urine, a concentration of 0.10 microg/ml of benzoylecgonine was also found.

Treatment of a 1,4-butanediol poisoning with fomepizole

BACKGROUND

Toxicity of 1,4-butanediol, an industrial solvent and a substance of abuse, is still misunderstood and not well documented. To date, only supportive treatments are used in this poisoning.

CASE REPORT

The case of a 43-year-old man who ingested 30 mL of a homemade 1,4-butanediol solution and who developed general seizures and coma has been reported here. An intravenous loading dose of fomepizole 10 mg/kg was started on admission and followed by two other doses of 10 mg/kg every 12 hour. He awoke shortly after fomepizole administration. Initial plasma 1,4-butanediol and gamma-hydroxybutyric acid concentrations, measured by gas chromatography-mass spectrometry, were 24 and 222 mg/L, respectively. Subsequent 1,4-butanediol and gamma-hydroxybutyric acid determination suggest that there was some further formate of gamma-hydroxbutyric acid after fomepizole was administered.

CONCLUSION

Fomepizole administration appeared safe in this 1,4-butanediol-intoxicated patient. It is unknown whether fomepizole influenced his clinical course, but the rapid awakening observed suggests that it may have been usefuL Further experience is needed, however, to define the efficacy of this antidotal therapy in 1,4-butanediol intoxication.

Capillary gas chromatographic determination of 1,4-butanediol and gamma-hydroxybutyrate in human plasma and urine

This article describes two methods for the determination of 1,4-butanediol and gamma-hydroxybutyrate in human plasma and urine using capillary gas chromatography. For 1,4-butanediol, plasma or urine samples (500 microl) were extracted by protein precipitation whereas for gamma-hydroxybutyrate, plasma or urine samples (500 microl) were extracted and derivatised with BF3-butanol. The compounds were separated on a Supelcowax-10 column and detection was achieved using a flame ionization detector. The methods are linear over the specific ranges investigated, accurate (with a percentage of the nominal concentration <109.8%) and showed intra-day and inter-day precision within the ranges of 5.0-12.0 and 7.0-10.1%, respectively. No interferences were observed in plasma and urine from hospitalized patients.

Urinary composition and postprandial blood changes in H-secoisolariciresinol diglycoside (SDG) metabolites in rats do not differ between acute and chronic SDG treatments

Although chronic exposure to secoisolariciresinol diglycoside (SDG) was shown to alter (3)H-SDG metabolite disposition in rats, the proportion of measured radioactivity attributed to known or unknown SDG metabolites was not determined. Using HPLC and GC-MS, two experiments were conducted to determine the effect of acute (1 d) vs. chronic (10 d) SDG treatment on major urinary metabolites of (3)H-SDG in female, Sprague-Dawley rats (70-72-d-old) over a 48-h period and if new urinary metabolites were detectable in rats fed nonradioactive flaxseed or SDG. A third experiment was conducted to determine changes in postprandial blood levels of (3)H-SDG metabolites over a 24-h period with acute or chronic SDG treatment. Regardless of treatment, enterodiol, enterolactone and secoisolariciresinol accounted for 75-80% of urine radioactivity. Four potential new lignan metabolites, two of which were detected in the urine of rats fed nonradioactive flaxseed or SDG, were found. Type of treatment had no effect on levels of individual urinary metabolites of (3)H-SDG. As observed for plasma lignans in women fed flaxseed, blood radioactivity peaked at 9 h and remained high until 24 h in both treatment groups, suggesting that blood lignan kinetics might be similar with flaxseed or SDG consumption and that they were comparable between humans and rats. In conclusion, the main urinary lignan metabolites were enterodiol, enterolactone and secoisolariciresinol. Urinary composition or blood levels of radioactive lignans were not affected by the duration of SDG exposure. Thus, while chronic SDG exposure alters lignan disposition in rats, it does not change the metabolite profile.

Blood and urinary levels of ethanol, acetaldehyde, and C4 compounds such as diacetyl, acetoin, and 2,3-butanediol in normal male students after ethanol ingestion

Aldehyde dehydrogenase (ALDH) isozyme 2 genes were determined in 15 students. Of these subjects, five healthy male students were administered 0.4 kg/kg ethanol. One subject was defective in aldehyde dehydrogenase 2 (ALDH2), two had normal ALDH2, and the other two were hetero type. After the intake of alcohol, the concentration of ethanol, acetaldehyde, and C4 compounds in blood and urine were determined. The student with the inactive form of ALDH2 was flushed and his levels of 2,3-butanediol and acetaldehyde in blood and urine were found to be the highest.

Alcohol-related diols cause acute insulin resistance in vivo

Epidemiological studies suggest that alcohol consumption is an independent risk factor for the development of non-insulin-dependent diabetes mellitus (NIDDM). Alcoholism is known to be associated with increased plasma levels of two novel diols, 2,3-butanediol and 1,2-propanediol, metabolites known to impair insulin action in isolated adipocytes. This study examines whether 2,3-butanediol and 1,2-propanediol have the capacity to impair insulin action acutely in vivo in the rat. Using the euglycemic-hyperinsulinemic clamp, it is shown that the two diols reduce whole-body glucose utilization (by approximately 30%), with the onset of insulin resistance in vivo occurring at plasma concentrations of 2,3-butanediol (33 micromol/L) at least one order of magnitude (P < .001) lower than 1,2-propanediol (432 micromol/L). Tracer methodologies using [U-14C]glucose and 2-deoxy[1-(3)H]glucose indicate that the reduction in whole-body glucose utilization is accompanied by a reduction in glucose uptake and glycogen synthesis in the skeletal muscle and heart. The association between elevated plasma diol levels and insulin resistance demonstrated in this report raises the question of whether there is a link between the high plasma diol levels in alcohol abusers and their increased susceptibility to NIDDM.

Proton nuclear magnetic resonance detects leucine, 2,3-butanediol, and a prominent increase in the level of choline in the sera from patients chronically infected with schistosomiasis japonica

1H-NMR spectroscopy with 'Hahn' spin-echo pulse sequence has been employed to investigate the metabolic profiles of sera of chronic patients with schistosomiasis japonica, and compared with those of healthy volunteers and former patients who had been treated successfully. 1H-NMR clearly detected 2,3-butanediol and leucine, and markedly elevated levels of choline in sera from the chronic patients. Profiles of the sera from former patients were essentially similar to those from healthy volunteers, except that ketone bodies (3-hydroxybutyrate and acetone) were detectable in sera from 58% of the former patients but not in those of the normal controls patients.

Effect of D- and L-1,3-butanediol isomers on glycolytic and citric acid cycle intermediates in the rat brain

DL-1,3-butanediol (DL-BD) is an ethanol dimer which affords cerebral protection in various experimental models of hypoxia and ischemia but its mechanism of action is unknown. DL-BD is a ketogenic alcohol and it has been proposed that its protective effect was accomplished through cerebral utilization of ketone bodies. Since DL-BD is a racemic, its metabolic effects could be due to D, L or both isomers. The effects of equimolar doses of DL-, D- and L-BD (25 mmol/Kg) on cerebral metabolism were studied by measuring the cortical levels of the main glycolytic (glycogen, glucose, glucose 6-phosphate, fructose 1,6-diphosphate, pyruvate and lactate) and citric acid cycle (citrate, alpha-ketoglutarate and L-malate) intermediates. The two BD isomers exerted different effects on cerebral metabolism. Unlike L-BD, D- and DL-BD treatments resulted in a slight (+10%) but significant increase in citrate level whereas L-BD treatment led to significant reduction in pyruvate (-12%) and lactate (-24%) levels. These effects were apparently not linked to hyperketonemia, since DL-BHB treatment, which mimicked hyperketonemia induced by DL-BD, had no effect on cerebral metabolites but might be due to intracerebral metabolism of BD.

Metabolism of (R,S)-1,3-butanediol acetoacetate esters, potential parenteral and enteral nutrients in conscious pigs

The (R,S)-1,3-butanediol-acetoacetate monoesters and diester are nonionized sodium-free precursors of ketone bodies (beta-hydroxybutyrate and acetoacetate). They represent a convenient form of ketone body administration for parenteral and enteral nutrition. We have studied the metabolism of the esters in the conscious pig, an animal in which ketogenesis is congenitally impaired. Some pigs were infused for 3 h, intravenously or intragastrically, with the esters or with (R,S)-1,3-butanediol at 30% of the hourly caloric requirement. Other pigs were given intragastric boluses of esters or of (R,S)-1,3-butanediol at 15% of the daily caloric requirement. Our data show that continuous infusion of the esters at 30% of the caloric requirement leads to low concentrations of (R,S)-1,3-butanediol (0.1 mM) and total ketone bodies (0.5 mM). In pigs given intragastric boluses of esters at 15% of the daily caloric requirement, concentrations of (R,S)-1,3-butanediol and total ketone bodies peaked briefly at 2-3 and 5 mM, respectively. No deleterious side effects were observed in any group, including no hypoglycemia and no acidosis. Thus the (R,S)-1,3-butanediol acetoacetate esters appears to be well utilized as a nutrient by the pig despite its impaired ketogenesis.

Assay of the enantiomers of 1,2-propanediol, 1,3-butanediol, 1,3-pentanediol, and the corresponding hydroxyacids by gas chromatography-mass spectrometry

We developed gas chromatographic-mass spectrometric assays for the enantiomers of 1,2-propanediol, 1,3-butanediol, 1,3-pentanediol, and their corresponding hydroxyacids, lactate, beta-hydroxybutyrate, and beta-hydroxypentanoate (3-hydroxyvalerate) in biological fluids. The corresponding ketoacids, acetoacetate and beta-ketopentanoate, can be assayed simultaneously by pretreating the samples with NaB2H4. The assays involve spiking the samples with deuterated internal standards, deproteinization, ether extraction, and derivatization of the carboxyl groups with (R,S)-2-butanol/HCl and of the hydroxyl groups with chiral (S)-(+)-2-phenylbutyryl chloride. Mass spectrometric analysis is conducted under ammonia positive chemical ionization. We used these assays to follow the metabolism of diol enantiomers in dogs. For (R,S)-1,3-butanediol and (R,S)-1,3-pentanediol, the uptakes from dog plasma of the R and S enantiomer of each diol were identical. In contrast, the metabolism of (S)-1,2-propanediol was faster than that of (R)-1,2-propanediol. (R)-1,2-Propanediol is formed during acetone metabolism, while (R,S)-1,3-butanediol and (R,S)-1,3-pentanediol are potential nutrients. The assays developed will allow further investigations of the metabolisms of acetone, (R)-lactate, and artificial nutrients derived from the 1,3-butanediol and 1,3-pentanediol enantiomers.

Simple and sensitive determination of 2,3-butanediol in biological samples by gas chromatography with electron-capture detection

2,3-Butanediol was quantitatively oxidized into diacetyl by reaction with MnO4- at 20 degrees C for 30 min under neutral conditions. The reaction of diacetyl with 4,5-dichloro-1,2-diaminobenzene afforded 6,7-dichloro-2,3-dimethyl-quinoxaline (DCDMQ), which was extracted with n-hexane and determined by gas chromatography with electron-capture detection. As an internal standard 1,2-cyclohexanediol was used. The detection limit of DCDMQ (or 2,3-butanediol) was 10 fmol/microliter in the extract, and the determination limit of DCDMQ (or 2,3-butanediol) was at least from 50 fmol/microliter to 20 pmol/microliter in the extract. Recoveries from normal rat urine and rat liver homogenate were 97.8 +/- 3.4% and 98.4 +/- 2.9%, respectively. The method is very simple and sensitive and is applicable to the determination of 2,3-butanediol in normal rat tissues.

2,3-Butanediol in plasma from an alcoholic mistakenly identified as ethylene glycol by gas-chromatographic analysis

2,3-Butanediol was mistakenly identified as ethylene glycol in plasma specimens from two alcoholic patients. The cyclic phenylboronate ester derivatives of 2,3-butanediol and ethylene glycol had the same retention time when OV-17 was used as the stationary phase for gas chromatography. This led to incorrect diagnosis of ethylene glycol poisoning and unnecessary invasive therapy. Plasma from two chronic alcoholics contained 2,3-butanediol at 3.5 and 3.4 mmol/L. The elimination half-life of 2,3-butanediol was 3.9 days when ethanol was administered during therapy for suspected ethylene glycol poisoning. Low concentrations of 2,3-butanediol might be present in blood of chronic alcoholics as a result of a novel pathway of intermediary metabolism associated with some forms of alcoholism. However, a more likely explanation for fairly high concentrations of 2,3-butanediol is enzymatic production from 2-butanone. This ketone occurs in denatured alcohol preparations often consumed by alcoholics in Sweden.

2,3-butanediol in experimental myocardial ischaemia in pigs

To investigate the role of 2,3-butanediol in myocardial ischaemia we analysed this compound in pig's myocardium and blood. Ischaemia was induced by ligation of a coronary artery. In the first study we found significantly higher levels of 2,3-butanediol in the homogenate of ischaemic myocardium than in non-ischaemic myocardium. The lactate concentration was also significantly elevated. In the second study, where ischaemia was similarly induced, and where reperfusion was achieved by re-opening the ligated coronary artery after 20 min, 2,3-butanediol in peripheral blood was found to increase significantly. In the pigs in which the coronary artery was not re-opened, the 2,3-butanediol level in peripheral blood was unchanged. We conclude that in pigs' anaerobic myocardia accumulation of 2,3-butanediol occurs; if the myocardium is reperfused this metabolite also appears in the blood.

Early appearance of 2,3-butanediol in acute myocardial infarction. A new marker for ischaemia?

In 28 patients with acute myocardial infarction, the release pattern of 2,3-butanediol (BD), a product of intermediary metabolism, and creatine kinase activity (CK) in blood were compared. Whereas CK at entry was low in all patients, the BD level was elevated in 18 (64%). However, BD returned to normal levels during the next 24 h whereas CK increased. The BD level at entry did not allow differentiation between patients with transmural or non-transmural infarction; it was independent of clinical findings and biochemical parameters. We suggest that, in patients with acute myocardial infarction, elevated levels of BD originates from myocardial metabolism. Whether it reflects ongoing ischaemia or reperfusion of the infarcted area remains unresolved.

Effects of ethanol on the kinetics of methyl ethyl ketone in man

The kinetics of inhaled methyl ethyl ketone (MEK) at a concentration of 200 ppm for four hours were studied in volunteers after swallowing ethanol at a dose of 0.8 g/kg. Ethanol was given either before or at the end of the exposure to MEK. The blood concentrations of MEK, 2-butanol, and 2,3-butanediol were monitored during and after the exposure. MEK concentrations in exhaled air and MEK and 2,3-butanediol concentrations in urine were also measured. Ethanol inhibited the primary oxidative metabolism of MEK and caused an increase in the blood concentrations of MEK and 2-butanol after ingestion. Ethanol ingestion, through higher blood MEK concentrations, also increased the elimination of MEK in the urine and exhaled air. Ethanol taken before exposure to MEK reduced the serum concentration of 2,3-butanediol initially but there was an increase about eight hours after the exposure. Urinary excretion of 2,3-butanediol followed the same pattern. Prior ingestion of ethanol thus seemed to interfere with the metabolism of 2,3-butanediol during and after exposure to MEK.

Assay of physiological levels of 2,3-butanediol diastereomers in blood and urine by gas chromatography-mass spectrometry

We present an assay for 2,3-butanediol by gas chromatography-mass spectrometry of its trimethylsilyl ethers. 2R,3R- and/or 2S,3S-2,3-butanediol and meso-2,3-butanediol are quantitated with corresponding internal standards of [2,3-2H2]butanediol. Limits of detection are 1 and 0.1 microM for split and splitless injections, respectively. Blood concentrations of 2,3-butanediol in nonalcoholics are 0.5 +/- 0.3 (SD) microM for 2R,3R- and/or 2S,3S-2,3-butanediol and 0.8 +/- 0.4 microM for meso-2,3-butanediol (n = 9). Two hours after alcohol ingestion, blood levels had risen in eight of nine subjects to 1.2 +/- 0.7 microM for 2R,3R-/2S,3S-2,3-butanediol and to 1.2 +/- 0.6 microM for meso-2,3-butanediol. Baseline urinary excretion of 2,3-butanediol is 0.4 +/- 0.2 mumol/mmol creatinine for 2R,3R-/2S,3S-2,3-butanediol and 0.9 +/- 0.5 mumol/mmol creatinine for meso-2,3-butanediol.

The measurement of D,L-2,3-butanediol in controls and patients with alcoholic cirrhosis

Plasma D,L-2,3-butanediol was measured in 53 controls and 50 patients with alcoholic cirrhosis, none of whom had measurable amounts of blood ethanol. Thirteen of 50 samples from patients with alcoholic cirrhosis had measurable D,L-2,3-butanediol. (range less than 5-154 microM). In one patient with alcoholic cirrhosis who had been abstinent from ethanol for over 5 years plasma levels of D,L-2,3-butanediol ranged between 154 and 211 microM over a one-year period. Only one of the 53 control subjects had detectable levels of D,L-2,3-butanediol. Although it has previously been reported that 2,3-butanediol is present in alcoholics consuming distilled spirits (Rutstein et al. (1983) Lancet ii, 534), this is the first report of the persistent presence of these compounds in alcoholics in the absence of ethanol. Clearly in abstinent alcoholics the presence of 2,3-butanediol is not due to the ingestion of undistilled spirits nor is it likely to arise directly from the metabolic products of ethanol. The presence of D,L-2,3-butanediol in patients with alcoholic cirrhosis and its absence in control subjects suggests that this compound may be a marker of some forms for alcoholism.

The appearance of 2,3-butanediol in the chronic ethanol treated pregnant rat

The chronic administration of ethanol to pregnant rats at term results in the appearance of high concentrations of glycols such as 2,3-butanediol and 1,2-propanediol in their blood and urine. The results support the idea that 2,3-butanediol formation could be a mechanism for ethanol detoxication. The clinical implications of the findings are referred to.

A gas-liquid chromatographic method for quantitation of 1,3-butylene glycol in whole blood or plasma and the separation of the short chain glycols

A microanalytical method with direct on-column specimen injection for determination of 1,3-butylene glycol (1,3-butanediol) in whole blood or plasma using gas-liquid chromatography with flame ionization is described. Whole blood or serum (minimum of 10 microL) was mixed with an equal volume of internal standard (1,2-propanediol, 50 mg/dL) and a 2-microL aliquot was injected onto the column without prior derivatization or extraction. The other short chain (C2 to C4) alkyldiols were separated by this method and did not interfere with the quantitation of 1,3-butylene glycol. The method was linear (y = 0.0206x + [-0.0073], r = 0.9990) over the range of 25 to 100 mg/dL and the coefficient of variation varied between 0.74 and 6.03%. Minimum detectable concentration of 1,3-butylene glycol was 5.0 mg/dL. The method described is suitable for the rapid detection of potentially toxic blood or plasma levels of 1,3-butylene glycol, as well as for the detection of other short chain glycols.

Ethanol potentiates the toxic effects of 1,4-butanediol

The simultaneous administration of ethanol increases the mortality rate and tissue damage observed in rats after 1,4-butanediol (1,4-BD). A related increase in tissue 1,4-BD concentration supported the hypothesis of an in vivo competition of the two substances for alcohol dehydrogenase. The clinical implications of the results, in light of the recent discovery of the presence of endogenous 1,4-BD in humans are discussed.

[Metabolism of lenampicillin hydrochloride. II. Metabolism of promoiety]

The in vitro and in vivo metabolism of promoiety in lenampicillin hydrochloride (LAPC) were investigated in rats and dogs. After incubation of LAPC with intestinal or liver preparations and blood of rat, diacetyl, acetoin and 2,3-butanediol were identified as metabolites of LAPC. The main metabolite in peripheral plasma was 2,3-butanediol after oral administration of LAPC in rats and dogs. On the other hand, high levels of acetoin were found out in portal plasma for early period after dosing of LAPC. These results suggested that the biotransformation of promoiety in LAPC to acetoin carried out mainly in intestinal tissues, but acetoin was converted to 2,3-butanediol in liver. Acetoin and 2,3-butanediol were also excreted in urine, but their urinary excretion were very low, and the combined excretion were accounting for about 9% of dose up to 48 hours after dosing in rats and less than 1% in dogs, respectively. The major metabolic pathways of promoiety in LAPC were postulated as below. (Formula: see text).

The measurement of 2,3-butanediol and 1,2-propanediol in "flushing" and "non-flushing" Japanese

Seven Japanese medical students, three "flushers" and four "non-flushers," were given 0.5 g ethanol/kg body weight PO in an attempt to assess whether elevated body acetaldehyde can account for 2,3-butanediol production in humans. Blood was taken from the anticubital vein immediately prior to, 30, 60, 90, and 120 min after ingestion of ethanol. No difference in the two groups was observed in 2,3-butanediol or in 1,2-propanediol. Measured 1,2-propanediol was in the normal range in both groups. No 2,3-butanediol was detected in any of the subjects.

Genetic and biochemical factors relevant to alcoholism

Important biochemical clues from animal and human studies as well as epidemiologic studies of twins and adoptees suggest that genetic factors may predispose to alcohol addiction. This paper critically examines the epidemiology and biochemistry literature to assess the strength of the evidence supporting a genetic element in alcohol addiction. Then, a biochemical hypothesis is presented that involves the identification of specific metabolic pathways, pathway controls, and metabolites that may be unique to alcoholics, and which has been tested by experiment.

The metabolism of acetone in rat

Intraperitoneal injection of 5 mumol of acetone/g, body weight, into 3 rats previously fed 1% acetone (v/v) in their drinking water resulted in the appearance in blood serum of 16 +/- 2 nmol of 1,2-propanediol/ml and 8 +/- 1 nmol of 2,3-butanediol/ml. No detectable 1,2-propanediol or 2,3-butanediol was found in the serum of animals after acetone or saline injection without prior addition of acetone to drinking water or in the serum of animals injected with saline after having been maintained on drinking water containing 1% acetone. These data suggest that acetone both acts to induce a critical enzyme or enzymes and serves as a precursor for the production of 1,2-propanediol. It is also clear from these data that chronic acetone feeding plays a role in 2,3-butanediol production in the rat. Microsomes isolated from the liver of animals maintained on drinking water supplemented with 1% acetone contained two previously unreported enzymatic activities, acetone monooxygenase which converts acetone to acetol and acetol monooxygenase which converts acetol to methylglyoxal. Both activities require O2 and NADPH. Prior treatment with acetone increased serum D-lactate from 9 nmol/ml +/- 9 nmol/ml in control animals to 77 +/- 36 nmol/ml in acetone-fed animals after injection with 5 mumol of acetone/g, body weight. This is consistent with methylglyoxal being a by-product of acetone metabolism. Two pathways for the conversion of acetone to glucose are proposed, the methylglyoxal and the propanediol pathways. The methylglyoxal pathway is responsible for the conversion of acetone to acetol, acetol to methylglyoxal, and the subsequent conversion of methylglyoxal to glucose. The propanediol pathway involves the conversion of acetol to L-1,2-propanediol by an as yet unknown process. L-1,2-Propanediol is converted to L-lactaldehyde by alcohol dehydrogenase, and L-lactaldehyde is converted to L-lactic acid by aldehyde dehydrogenase. Expression of these metabolic pathways in rat appears to be dependent on the induction of acetone monooxygenase and acetol monooxygenase by acetone.

Gas-liquid chromatographic determination of propylene glycol in plasma and urine

We describe a gas-chromatographic assay for propylene glycol in human plasma and urine. The method is sensitive enough to allow quantification of the compound at concentrations observed clinically. It requires no derivative preparation and takes only 13 min of chromatographic time.

2,3-butanediol: an unusual metabolite in the serum of severely alcoholic men during acute intoxication

In a controlled experiment 15 (79%) of 19 severely alcoholic men but only 1 of 22 controls had a serum concentration of greater than or equal to 5 mumol/l 2,3-butanediol after ingestion of distilled spirits. Another diol, 1,2-propanediol, was found in a concentration of greater than or equal to 5 mumol/l in all patients' specimens after drinking; but it was also present in lower concentrations in the reference specimens of most of the patients. These data are consistent with the experimental evidence that ethanol can be metabolised in rats to produce 2,3-butanediol and with the epidemiological hypothesis that severely alcoholic men metabolise ethanol by a different pathway than do control subjects.

Electron-capture, capillary column gas chromatographic determination of low-molecular-weight diols in serum

Research on alcoholism has revealed that concentrations of 1,2-propanediol, d,1-2,3-butanediol and meso-2,3-butanediol may be greater in the serum of chronic alcoholics than in the serum of social drinkers and nondrinkers. In connection with one of these studies, we developed methodology to determine these diols at the micromolar levels in 500 serum samples. The procedure consisted primarily of extraction of the serum with acetonitrile containing internal standard. The extract was then concentrated to dryness and reacted with p-bromophenylboric acid. The reaction mixture was injected into a gas chromatograph fitted with a capillary column and an electron-capture detector. The total coefficients of variation were best for 1,2-propanediol, 6.82 and 10.00%, and worst for d,1-2,3-butanediol, 13.64 and 19.22%. The observed means for the analytes were all within 10% of the spiked level.

Metabolites of glucose in the blood of patients with renal failure

The blood concentrations of pyruvate and of some of its metabolites and the red cell 2,3-diphosphoglycerate concentration were compared with the severity of uraemia in 103 patients with renal failure. In chronic renal failure 2,3-butylene glycol was distinctly elevated, and a positive linear correlation (2p Less Than 0.001) with the urea was found. The values were even higher in corresponding patients with uraemic pericarditis, but,--taking into account their relation to the urea--,they were not elevated in acute renal failure. Acetaldehyde, acetoin and acetate behaved in part likewise. Severe uraemia, which clinically was demonstrated by uraemic pericarditis, was characterized biochemically, without regard to the urea, by very elevated values of 2,3-butylene glycol and acetaldehyde and of the pyruvate: lactate ratio. In addition, the chronic patients who were not undergoing regular haemodialysis, did not show the expected rise of 2,3-diphospho-glycerate along with progressive anaemia. The data suggest that the uraemic state is characterized by the impairment of the oxidative glucose metabolism between pyruvate and the tricarbonic acid cycle more precisely than by the blood urea.

The presence of 2,3-butanediol in the blood of chronic alcoholics admitted to an alcohol treatment center

Fifty-one of sixty-three unselected alcoholic subjects had 2,3-butanediol in their blood in concentrations ranging from 0.011 to 0.775 mM upon admission to an alcohol detoxification center. The concentration of 2,3-butanediol was below the detection limit of 0.01 mM in twelve non-alcoholic controls. Eighteen hours after admission, second blood samples showed no ethanol in all eleven subjects tested. 2,3-Butanediol levels declined in all of the patients and became undetectable in eight.

High levels of endogenous 1,3-butanediol in the blood of a man after ethanol ingestion

A young man was found to have 1,3-butanediol in his blood, much more after ethanol ingestion. This substance reacted in the enzyme procedure for measuring blood alcohol, giving falsely high values. The 1,3-butanediol was detected by gas chromatography.