A case of fatal acebutolol poisoning: an illustration of the potential of molecular networking.

Acebutolol is a ß1-selective adrenergic receptor antagonist with moderate membrane-stabilizing activity and intrinsic sympathomimetic activity; accordingly, the drug is indicated in hypertension, angina pectoris, and arrhythmia. However, acebutolol's beta-blocking properties also extend the QRS and QTc intervals, and may predispose the patient to ventricular tachydysrhythmia. Here, we report autopsy and toxicological findings on a fatal case of acebutolol self-poisoning in a 70-year-old woman. Toxicological analyses of post-mortem samples (using a liquid chromatography high-resolution mass spectrometry (LC-HR-MS) method) highlighted high concentrations of acebutolol and its metabolite diacetolol in femoral blood (92.8 mg/L and 21.2 mg/L, respectively) and other matrices (cardiac blood, urine, bile, and gastric contents). A molecular networking approach provided useful information on acebutolol's metabolism and revealed the existence of an unknown phase II metabolite of acebutolol. Molecular networking also facilitated visualization of the complex LC-HR-MS/MS datasets and the sample-to-sample comparisons that confirmed massive acebutolol intoxication by ingestion.

Analysis of 27 ß-Blockers and Metabolites in Milk Powder by High Performance Liquid Chromatography Coupled to Quadrupole Orbitrap High-Resolution Mass Spectrometry.

This paper presents an application of high performance liquid chromatography coupled with quadrupole orbitrap high-resolution mass spectrometry (HPLC-Q-Orbitrap HRMS) for the analysis of 27 ß-blockers and metabolites in milk powder. Homogenized milk power samples were extracted by acetonitrile and purified by using Oasis PRiME HLB solid-phase extraction cartridges. The Ascentis® C8 chromatographic column was used to separate the analytes. The quantification was achieved by using matrix-matched standard calibration curves with carazolol-d7 and propranolol-d7 as the internal standards. The results show an exceptional linear relationship with the concentrations of analytes over wide concentration ranges (0.5⁻500 µg kg-1) as all the fitting coefficients of determination r² are > 0.995. All the limits of detection (LODs) and quantitation (LOQs) values were within the respective range of 0.2⁻1.5 µg kg-1 and 0.5⁻5.0 µg kg-1. Overall average recoveries were able to reach 66.1⁻100.4% with the intra- and inter-day variability under 10%. This method has been successfully applied to the screening of ß-blockers and metabolites in commercial milk powders. At the same time, the corresponding characteristic fragmentation behavior of the 27 compounds was explored. The characteristic product ions were determined and applied to the actual samples screening.

Synthesis and In Vitro Pharmacological Evaluation of 5-(Alkoxymethyl)-2-(3-alkylamino-2-hydroxypropoxy)phenylethanones Related to Acebutolol and Celiprolol.

The structure-activity relationships of 13 analogs of aryloxyaminopropanol type derived from 2-hydroxyphenylethanone as potential ß-blockers are described. The synthesized compounds possess an isopropyl or a tert-butyl group in the hydrophilic part of the molecule and an alkoxymethyl substitution in the lipophilic moiety. The target compounds were prepared by an established four-step method and their structures were confirmed by interpretation of their UV, IR, (1) H NMR and (13) C NMR spectra, and by elemental analysis. The ß-adrenolytic efficacy of the prepared racemic compounds was determined on isolated guinea pig atria (ß1 ) and trachea (ß2 ) and expressed as pA2 values against isoprenaline tachycardia. The assumed cardioselectivity was expressed as ß1 /ß2 ratio and the values of compounds with an alkoxy group (CH3 O, iC3 H5 O, C5 H11 O, CH2 CHCH2 O, CH3 OCH2 CH2 O) in the lipophilic part and with tert-butyl in the hydrophilic part of the molecule were found to be comparable or higher than those of the standards acebutolol and celiprolol. All evaluated substances at a concentration of 10(-7) mol/dm(3) showed also negative chronotropic effects.

Using supported liquid extraction together with cellobiohydrolase chiral stationary phases-based liquid chromatography with tandem mass spectrometry for enantioselective determination of acebutolol and its active metabolite diacetolol in spiked human plasma.

A high through-put, sensitive, and enantioselective LC-MS/MS-based bioanalytical method was developed and validated for the simultaneous determination of individual acebutolol (AC) and its active metabolite-diacetolol (DC) enantiomers in human plasma using cellobiohydrolase (CBH) chiral stationary phases (CSP). Systematic optimization of chromatographic conditions including organic content, buffer concentration, and pH of mobile phases was conducted to improve the through-put for the direct separation of both AC and DC on CBH column during method development. Complete baseline separation of enantiomeric AC and DC was achieved within 1.5 min with a LC flow rate of 0.9 ml/min under method validation conditions. To further improve the assay through-put, supported liquid extraction (SLE) in a 96-well plate format was used for sample extraction. The method validation was conducted over the curve range of 0.0500-50.0 ng/ml for each AC and DC enantiomer using 0.100 ml of plasma sample. The intra- and inter-day precision and accuracy of the quality control samples at low, medium, and high concentration levels showed

Effects of grapefruit juice on the pharmacokinetics of acebutolol.

AIMS: We aimed to investigate effects of grapefruit juice on acebutolol pharmacokinetics. METHODS: In a randomized cross-over study, 10 healthy subjects ingested 200 mL grapefruit juice or water three times daily for 3 days and twice on day 4. On day 3, each subject ingested 400 mg acebutolol with grapefruit juice or water. The concentrations of acebutolol and its metabolite diacetolol were measured in plasma and urine up to 33 h. RESULTS: Grapefruit juice decreased the peak plasma concentration (Cmax) of acebutolol by 19% from 872 +/- 207 ng mL(-1) to 706 +/- 140 ng mL(-1) (95% CI on the difference -306, -26.4; P < 0.05), and the area under the concentration time curve (AUC(0-33 h)) by 7%, from 4498 +/- 939 ng mL(-1) h to 4182 +/- 915 ng mL(-1) h (95% CI -609, -23.0; P < 0.05). The half-life (t1/2) of acebutolol prolonged from 4.0 to 5.1 h (P < 0.05). The time to peak concentration and the amount of acebutolol excreted into urine (Ae) were unchanged. The Cmax, AUC(0-33 h), and Ae of diacetolol were decreased by 24% (P < 0.05), 18% (P < 0.05), and 20% (P < 0.01), respectively, by grapefruit juice. CONCLUSION: Grapefruit juice caused a small decrease in the plasma concentrations of acebutolol and diacetolol by interfering with gastrointestinal absorption. The interaction between the grapefruit juice and acebutolol is unlikely to be of clinical significance in most of the patients.

Influence of cimetidine co-administration on the pharmacokinetics of acebutolol enantiomers and its metabolite diacetolol in a rat model: the effect of gastric pH on double-peak phenomena.

Acebutolol (AC) is a chiral beta-adrenergic receptor-blocking agent, which has been shown to be clinically effective in hypertension. The plasma concentration-time profiles of AC exhibit two peaks following oral administration of racemate for both R- and S-enantiomers. In the present study, the absorption of AC after a single dose was studied as a function of gastric pH in male Sprague-Dawley rats. Furthermore, the effect of cimetidine (CIM) on pharmacokinetic parameters of AC and its metabolite diacetolol (DC) was evaluated. CIM (50 mg kg(-1)) was administered via jugular vein 30 min prior to AC administration to elevate the intragastric pH. AC (50 mg kg(-1)) was administered orally by gavage and serial blood samples were collected before and for 8h after AC administration. Plasma samples were assayed for AC and DC, pharmacokinetic parameters were estimated and compared with those of control. The concentration-time profiles and the pharmacokinetics of AC were unchanged after co-administration of CIM. The oral absorption of AC, as assessed by the area under the plasma concentration-time curve (AUC) and the amount of unchanged drug recovered in the urine were not affected by CIM. The amount of metabolite recovered in the urine and the rate of absorption, however, were significantly altered. These are unlikely to be of clinically importance as we have found that the extent of absorption was not changed. We, therefore, concluded that intragastric elevation of pH has no effect either on generation of multiple peaking or on pharmacokinetic parameters of AC.

Pharmacokinetics of acebutolol and its main metabolite, diacetolol after oral administration of acebutolol in rabbits with carbon tetrachloride-induced hepatic failure.

Pharmacokinetic characteristics of acebutolol and its main metabolite, diacetolol, following a single 10 mg/kg oral dose, were investigated in rabbits with carbon tetrachloride-induced hepatic failure. Plasma concentrations of acebutolol and diacetolol were determined by a high performance liquid chromatography assay. The area under the plasma concentration-time curves (AUC) and maximum plasma concentration (Cmax) of acebutolol were significantly increased in moderate and severe carbon tetrachloride-induced hepatic failure rabbits. The ratio of the diacetolol to total acebutolol in plasma (i.e., metabolite percentage rate) was significantly decreased in moderate and severe carbon tetrachloride-induced hepatic failure rabbits. Volume of distribution (Vd) and total body clearance (CL1) of acebutolol were significantly decreased in moderate and severe carbon tetrachloride-induced hepatic failure rabbits. Slope of terminal phase (beta) of acebutolol was significantly decreased in hepatic failure rabbits. These findings suggest that the Vd, CL1 and beta of acebutolol were significantly decreased as a result of inhibition of the hepatic metabolism in moderate to severe hepatic failure rabbits. Therefore, dose adjustment may be necessary for acebutolol in hypertensive patients with hepatic damage.

Enantioselective high performance liquid chromatographic assay of acebutolol and its active metabolite diacetolol in human serum.

A stereoselective direct liquid chromatographic method for assay of the enantiomers of the beta-adrenergic blocker acebutolol (AC) and its active metabolite, diacetolol (DC), in human serum was developed. The assay is based on extraction with ethyl acetate and separation of enantiomers on an amylose tris-(3,5-dimethylphenylcarbamate) chiral stationary phase (Chiralpak AD) column. The method was validated and proved useful for the determination of the enantiomers in serum samples of patients suffering from hypertension and chronically treated with racemic AC. The results were compared and found similar with an indirect assay based on derivatization of the enantiomers with (+)-(S)-1-(1-naphthyl)ethyl isocyanate (NEIC).

Effect of adjuvant arthritis on the disposition of acebutolol enantiomers in rats.

Disease states such as arthritis may interact with the kinetics of beta-blockers. Acebutolol (AC) is a chiral beta-blocker which is available as a racemate. The beneficial properties of AC, however, is attributed mainly to the S-(+)-enantiomer. The disposition of AC enantiomers and their active, chiral metabolites, diacetolol (DC) were examined after oral administration to healthy and adjuvant-induced arthritic (AA) female Sprague-Dawley rats. Arthritis was induced by tail base injection of Mycobacterium butyricum. Swelling of hind and forepaws were apparent in 10-16 days in AA but not controls. Control and AA rats were sacrificed at 0.5, 1, 2, 4, 6 and 8 h after a 25 mg/kg oral AC dose and blood was collected (n = 6). Significant three to tenfold increases in the initial plasma concentrations (0.5-2 h) of AC were observed in AA. Enantiomers were equally affected, thus AC S:R ratio was not changed. Higher plasma concentrations of the metabolite were only significant at 2 h. The ratio of DC:AC, however, was unaffected by AA. The DC S:R ratio was significantly decreased at 0.5 and 1 h in AA. The limited protein binding of AC (10%) was neither stereoselective nor affected by AA. Reduced intrinsic clearance in AA may be responsible for these observations.

Effect of aging on the pharmacokinetics of acebutolol enantiomers.

Acebutolol (AC) is a chiral beta-blocker that is metabolized to an equipotent chiral metabolite, diacetolol (DC). A stereoselective disposition of AC and DC enantiomers has recently been reported in young healthy subjects. As many physiologic properties affecting drug disposition are progressively altered with increasing age, the effect of aging on the pharmacokinetics of AC and DC enantiomers were investigated in nine subjects ranging from 60 to 75 years after administration of an oral 200-mg dose of racemic AC. Increasing age resulted in a significant prolongation of the elimination t1/2s of R- (r = 0.913) and S-DC (r = 0.811). Also, the S:R ratios of AC urinary excretion (sigma Xu) of enantiomers was significantly correlated with age (r = 0.677). Contribution of declining renal function to age-associated pharmacokinetics changes was subsequently examined. Renal clearance and cumulative urinary excretion of both AC and DC enantiomers were positively correlated with creatinine clearance. In addition, declining creatinine clearance was associated with a subsequent decline in the enantiomer S:R ratio of AC in plasma (AUC S:R, r = 0.807) and urine (sigma Xu S:R r = 0.807). Similarly, a progressive decline in the S:R ratio of DC collected in urine was evident (r = 0.689). Age-related changes in the enantiomers ratios may suggest that an active stereoselective pathway such as renal tubular secretion or nonrenal excretion may be affected in the elderly.

Pharmacokinetics of acebutolol enantiomers in humans.

The chiral beta-blocker acebutolol (AC) is marketed as a racemic mixture. Both AC and its major metabolite, diacetotol (DC), are chiral, the S-enantiomer possessing beta-blocking activity. The pharmacokinetics of AC and DC enantiomers was determined in 12 healthy subjects following oral administration of 200 mg of AC. Plasma and urine were collected over a 24-hr period and both AC and DC enantiomers were measured utilizing a stereospecific HPLC assay. Concentrations of S-AC were predominant in both plasma and urine [AUC S:R, 1.20 +/- 0.1; cumulative urinary excretion (sigma Xu) S:R, 1.17 +/- 0.05), which corresponded to a significantly greater oral clearance of R-AC (106 +/- 30 L/h) than S-AC (87 +/- 22 L/h). The Cmax of R-DC was significantly greater than for S-DC (S/R 0.7 +/- 0.1). The half-life (t1/2) of R-DC (6.4 +/- 1.6 h) was significantly shorter than that of S-DC (8.8 +/- 2.4 h). The observed AUC values for R- and S-DC were not significantly different. Renal clearance of R-DC (70 +/- 34 mL/min) was significantly greater than that of S-DC (53 +/- 29 mL/min). The data suggest that the first-pass metabolism of R-AC to R-DC is stereoselective. This metabolism, coupled with the stereoselective renal excretion of R-DC is likely a major contributor to the observed stereoselective disposition of AC and its major metabolite in humans.

[Acebutolol and diacetolol: their binding to plasma proteins and erythrocytes and secretion with the saliva]. / Atsebutolol i diatsetolol: sviaz' s belkami plazmy i éritrotsitami, sekretsiia so sliunoi.

Thirty-two patients with hypertensive disease were treated with a cardioselective blocker of beta-adrenergic receptors acebutolol ("Sectral-400", Rhone Poulenc, France). The binding of the drug and its metabolites diacetolol to plasma proteins and erythrocytes and their excretion with the saliva were studied. The significant binding of acebutolol and diacetolol to erythrocytes was shown. The ratio of the content of the free form of these substances in erythrocytes to plasma content was on the average 1.54 +/- 0.96 for diacetolol and 1.93 +/- 1.01 for acebutolol. A good correlation of acebutolol and diacetolol contents in the saliva with their contents in plasma was found. The mean values of the protein-bound fraction were for acebutolol 0.133 +/- 0.038 and for diacetolol 0.106 +/- 0.050.

Acebutolol and diacetolol plasma levels in patients undergoing myocardial revascularization with hypothermic cardiopulmonary bypass.

Cardiopulmonary bypass (CPB) has been reported to alter the disposition of numerous drugs and consequently to modify their plasma levels. The present study was designed to delineate the time course of acebutolol (a cardioselective beta-blocker) and diacetolol (its main metabolite) plasma levels in seven patients undergoing myocardial revascularization with hypothermic CPB. All patients were given oral acebutolol twice daily until 3 hours before surgery. Initiation of CPB produced an immediate and significant, but transient, decrease in acebutolol and diacetolol plasma concentrations. Cessation of CPB was not associated with an increase in plasma beta-blocker levels. It is concluded that CPB does not induce major alterations in the time course of acebutolol and diacetolol plasma concentrations.

Acebutolol: a review of its pharmacology, pharmacokinetics, clinical uses, and adverse effects.

Acebutolol is a new hydrophilic, cardioselective beta-adrenergic-blocking agent that possesses partial agonist and membrane-stabilizing activities. In the treatment of mild to moderate essential hypertension, once-daily acebutolol as monotherapy provides effective control in a large majority of patients and produces a further reduction in blood pressure when used concomitantly with diuretics. Acebutolol is as effective as other beta-blocking agents, and in a large, double-blind, parallel study against propranolol was found to cause less reduction in heart rate, and fewer neurologic side effects and patient withdrawals due to adverse effects. Oral acebutolol is also effective in suppressing premature ventricular contractions, and in small numbers of patients generally beneficial results were obtained in supraventricular and ventricular arrhythmias with intravenous administration. These salutary effects are attributable to beta blockade. Controlled clinical trials documented the antianginal actions of oral acebutolol in chronic stable angina pectoris; its efficacy in this regard is comparable to that of other beta-blocking agents. The drug produces smaller decreases in heart rate and cardiac output and alterations in peripheral vascular hemodynamics than beta-blocking drugs without partial agonist activity, and because of its cardioselectivity, it may be used cautiously in patients with bronchospastic disease. Acebutolol has minimal metabolic effects and does not elevate levels of blood lipids during long-term therapy; high-density-lipoprotein cholesterol increased with acebutolol in a small number of patients.

Comparison of beta-adrenoceptor selectivity of acebutolol and its metabolite diacetolol with metoprolol and propranolol in normal man.

The beta-adrenergic selectivity of diacetolol, the major metabolite of acebutolol, has been compared with that of acebutolol, metoprolol and propranolol in 11 normal subjects. Bronchial and cardiac beta-adrenoceptor blockade were assessed on separate occasions after diacetolol 600 mg, acebutolol 400 mg, metoprolol 200 mg, propranolol 80 mg and placebo. Bronchial beta-adrenoceptor blockade was assessed as the displacement of the bronchodilator dose response curve to inhaled isoprenaline after each beta blocking drug compared to placebo and expressed as the dose ratio. Bronchodilatation was measured as change in specific airway conductance (sGaw) in the body plethysmograph. Cardiac beta-adrenoceptor blockade was assessed as the percentage reduction in exercise heart rate during the 5th minute of exercise at 70% of the subject's maximum work rate. There was a significant reduction in exercise heart rate with all 4 beta-blocking drugs when compared with placebo, 22% for diacetolol, 24% for acebutolol, 25% for propranolol and 28% for metoprolol. The reduction with metoprolol was significantly greater than the reduction with the other three beta-adrenoceptor antagonists. Mean dose ratios for the airway isoprenaline dose response curves after each of the 4 beta-blocking drugs were 2.4 for diacetolol, 2.7 for metoprolol, 8 for acebutolol and 72 for propranolol. The difference between diacetolol and metoprolol was not significant. Thus diacetolol appears to be more cardioselective than acebutolol and both are more cardioselective than propranolol in man. Metoprolol is probably more cardioselective than diacetolol though interpretation of the differences in exercise heart rate is complicated by the fact that diacetolol has some intrinsic sympathomimetic activity.

To nurse when receiving acebutolol: is it dangerous for the neonate?

The concentrations of acebutolol and of its main active metabolite diacetolol in milk and plasma were studied in 7 hypertensive mothers treated with acebutolol, a cardioselective beta-adrenoceptor blocking agent. Clinical monitoring on their newborn babies was also done, as well as measurement of plasma level of the drug in them. The ratio between milk and plasma concentrations ranged from 1.9 to 9.2 for acebutolol and from 2.3 to 24.7 for diacetolol, and in any given milk sample, the diacetolol concentration was always higher than that of acebutolol. In a newborn infant, plasma concentrations of the two transplacentally acquired substances was raised when breast feeding started and remained high. Clinical signs of pharmacological beta-blockade were observed. Evaluation of the iatrogenic risk shows that pharmacologically active amounts of acebutolol might be received by a neonate if the daily maternal dosage exceeds 400 mg/day and/or renal function in the mother is impaired.

Pharmacologic properties of acebutolol: relationship of hydrophilicity to central nervous system penetration.

Studies in various animal models have shown acebutolol to be a relatively cardioselective beta-adrenoceptor-blocking agent possessing both partial agonist and membrane-stabilizing activities. The latter property may not be significant at clinically used doses. Acebutolol has both antihypertensive and antiarrhythmic effects. As with beta blockers in general, the antihypertensive mechanism of acebutolol is not known. The antiarrhythmic activity of acebutolol may be related to beta blockade. Acebutolol is relatively hydrophilic and does not readily cross the blood-brain barrier, a fact that may be clinically significant in reducing the frequency and severity of central nervous system adverse effects. The pharmacologic profile of diacetolol, acebutolol's major metabolite, is similar to that of the parent compound in beta-blocking potency, cardioselectivity, and partial agonist activity. Diacetolol, however, does not possess membrane-stabilizing activity.

Clinical pharmacology of acebutolol.

The clinical pharmacology and pharmacokinetics of acebutolol are summarized. Acebutolol and its longer-acting metabolite, diacetolol, are rapidly absorbed into the circulation from the gastrointestinal tract, and their bioavailability, unlike that of propranolol and metoprolol, is not significantly altered by whether the patient has recently eaten. Acebutolol is extensively metabolized by the liver, and elimination pathways involve approximately 30% to 40% through renal excretion and 50% to 60% by nonrenal mechanisms, including the bile and direct passage through the intestinal wall. The decreased hepatic metabolism and renal clearance rates seen in elderly patients may lead to the accumulation of both acebutolol and its metabolite, as has been reported with propranolol. In studies conducted to ascertain acebutolol's possible effect on common concurrently administered medications, the drug did not significantly alter either serum digoxin levels or serum insulin levels in diabetic patients treated with tolbutamide, nor did it change prothrombin time in patients treated with sodium warfarin.