OBJECTIVETo study the pharmacokinetics of propranolol and metoprolol in rats after acute exposure to high altitude.

METHODSWistar rats were randomly assigned into 4 groups for treatment with intragastric administration of propranolol or metoprolol after acute exposure to high altitude (4010 m) or normal altitude (50 m). Venous blood samples were collected from the rats at different time points after drug administration to determine the drug concentrations in the plasma and plasma ultrafiltrate using liquid chromatography-mass spectrometry (LC-MS/MS).

RESULTSThe protein binding rate of propranolol was significantly increased but that of metoprolol remained unchanged after acute exposure to high altitude. Compared with the rats exposed to normal altitude, the rats with acute exposure to high altitude showed significant alterations in the pharmacokinetic parameters of the drugs, shown by increased Cmax and AUC, prolonged t1/2 and MRT, and lowered Clz/F of propranolol, and by increased Tmax and prolonged t1/2 and MRT of metoprolol without obvious changes of the parameters of the compartmental model.

CONCLUSIONSignificant changes in the pharmacokinetics of propranolol and metoprolol occur in rats after acute exposure to high altitude possibly in relation to, apart from the changes in plasma protein binding ratio and blood gas, alterations in metabolic enzyme activities, increased blood viscosity, and species and general conditions of the animals.

Altitude ; Animals ; Chromatography, Liquid ; Metoprolol ; pharmacokinetics ; Propranolol ; pharmacokinetics ; Protein Binding ; Rats ; Rats, Wistar ; Tandem Mass Spectrometry

OBJECTIVETo investigate the value of metoprolol injection at dobutamine-atropine stress echocardiography (DASE) for detection of coronary artery disease (CAD).

METHODSDASE was performed in 72 patients with suspected CAD. All the patients received rapid metoprolol injection immediately after getting peak heart rate at DASE (DASE-Meto) and were subjected to coronary angiography (CAG) within two weeks. Regional wall motion and haemodynamic parameters at peak heart rate during DASE and after metoprolol injection were analyzed, and DASE and DASE-Meto results were compared with CAG.

RESULTSThere were 35 patients with CAG positive and 37 negative. The sensitivity, specificity, accuracy and positive and negative predictive values of DASE for detecting CAD were 65.7%, 86.5%, 76.4%, 82.1% and 84.6%, respectively. There were 10 patients with positive result at CAG undetected by DASE but observed regional wall motion abnormality (RWMA) after metoprolol injection. So the sensitivity, specificity, accuracy and positive and negative predictive values of DASE-Meto for detecting CAD were 94.3%, 83.8%, 88.9%, 72.7%, 93.9%, respectively. After metoprolol injection, the symptoms caused by the medicine used in detection were alleviated soon and recovery time was shortened.

CONCLUSIONThe use of metoprolol at DASE can improve the accuracy and security of CAD detection.

Aged ; Coronary Disease ; diagnostic imaging ; Echocardiography, Stress ; methods ; Female ; Humans ; Male ; Metoprolol ; Middle Aged ; Predictive Value of Tests ; Sensitivity and Specificity

Adrenergic beta-Antagonists ; analysis ; Analgesics, Opioid ; analysis ; Chromatography, High Pressure Liquid ; methods ; Humans ; Metoprolol ; analysis ; Tramadol ; analysis

BACKGROUND: Postural tachycardia syndrome (POTS) is a common childhood disease that seriously affects the patient's physical and mental health. This study aimed to investigate whether pre-treatment baseline left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) values were associated with symptom improvement after metoprolol therapy for children and adolescents with POTS. METHODS: This retrospective study evaluated 51 children and adolescents with POTS who received metoprolol therapy at the Peking University First Hospital between November 2010 and July 2019. All patients had completed a standing test or basic head-up tilt test and cardiac echocardiography before treatment. Treatment response was evaluated 3 months after starting metoprolol therapy. The pre-treatment baseline LVEF and LVFS values were evaluated for correlations with decreases in the symptom score after treatment (ΔSS). Multivariable analysis was performed using factors with a P value of <0.100 in the univariate analyses and the demographic characteristics. RESULTS: A comparison of responders and non-responders revealed no significant differences in demographic, hemodynamic characteristics, and urine specific gravity (all P > 0.050). However, responders had significantly higher baseline LVEF (71.09% ± 4.44% vs. 67.17% ± 4.88%, t = -2.789, P = 0.008) and LVFS values (40.00 [38.00, 42.00]% vs. 36.79% ± 4.11%, Z = -2.542, P = 0.010) than the non-responders. The baseline LVEF and LVFS were positively correlated with ΔSS (r = 0.378, P = 0.006; r = 0.363, P = 0.009), respectively. Logistic regression analysis revealed that LVEF was independently associated with the response to metoprolol therapy in children and adolescents with POTS (odds ratio: 1.201, 95% confidence interval: 1.039-1.387, P = 0.013). CONCLUSIONS Pre-treatment baseline LVEF was associated with symptom improvement after metoprolol treatment for children and adolescents with POTS.
Adolescent ; Child ; Humans ; Metoprolol/therapeutic use* ; Postural Orthostatic Tachycardia Syndrome/drug therapy* ; Retrospective Studies ; Stroke Volume ; Ventricular Function, Left

OBJECTIVE: To study the effect of CYP2D610 (c.100 C>T) on plasma trough concentrations of metoprolol and its metabolite α-hydroxy metoprolol, blood pressure and heart rate in patients with coronary artery disease. METHODS: The patients with coronary artery disease taking metoprolol tablets (=128) and those taking metoprolol sustained-release tablets (=126) were genotyped for CYP2D610 using Taqman real-time quantitative PCR. The trough concentrations of metoprolol and α-hydroxy metoprolol were determined with UPLC-MS/MS, and the dose-normalized concentrations (C/D) were compared among the patients with different CYP2D610 genotypes in both groups. Resting blood pressure and heart rate were recorded in all the patients when the concentration of metoprolol reached the steady state and were compared among the patients with different genotypes. RESULTS: In patients taking metoprolol sustained-release tablets, the plasma trough concentration of α-hydroxy metoprolol was significantly associated with the systolic blood pressure (=0.0204). The CYP2D610 poor metabolizers showed a significant association with the C/D of metoprolol and α-hydroxy metoprolol ( < 0.01) in patients receiving metoprolol in both formulations, and in both groups, the C/D of metoprolol was significantly higher in the patients with a TT genotype than in those with a CC or CT genotype ( < 0.01); compared with those with the CT genotype, the patients with the TT genotype had a significantly lower C/D of α-hydroxy metoprolol ( < 0.01). In patients taking metoprolol sustained-release tablets, those with the CT (=0.0281) and TT (=0.0196) genotypes had lower diastolic blood pressure than patients with the CC genotypes, but the systolic blood pressure or heart rate did not differ significantly among them. CONCLUSIONS CYP2D610T allele mutation can reduce the metabolism of metoprolol, increase the C/D of metoprolol and decrease the C/D of α-metoprolol and diastolic blood pressure in patients with coronary artery disease, but CYP2D610 variation does not significantly affect systolic blood pressure or heart rate in the patients when the concentration of metoprolol reaches a steady state.
Adrenergic beta-Antagonists ; Chromatography, Liquid ; Coronary Artery Disease ; Cytochrome P-450 CYP2D6 ; Genotype ; Humans ; Metoprolol ; Tandem Mass Spectrometry

Cardiovascular and central nervous system (CNS) toxicity, including tachydysrhythmia, agitation, and seizures, may arise from cocaine or bupropion use. We report acute toxicity from the concomitant use of cocaine and bupropion in a 25-year-old female. She arrived agitated and uncooperative, with a history of possible antecedent cocaine use. Her electrocardiogram demonstrated tachycardia at 130 beats/min, with a corrected QT interval of 579 ms. Two doses of 5 mg intravenous metoprolol were administered, which resolved the agitation, tachydysrhythmia, and corrected QT interval prolongation. Her comprehensive toxicology screen returned positive for both cocaine and bupropion. We believe clinicians should be aware of the potential for synergistic cardiovascular and CNS toxicity from concomitant cocaine and bupropion use. Metoprolol may represent an effective initial treatment. Unlike benzodiazepines, metoprolol directly counters the pharmacologic effects of stimulants without respiratory depression, sedation, or paradoxical agitation. A lipophilic beta-blocker, metoprolol has good penetration of the CNS and can counter stimulant-induced agitation.
Adult ; Benzodiazepines ; Bupropion ; Central Nervous System ; Cocaine ; Dihydroergotamine ; Electrocardiography ; Female ; Humans ; Metoprolol ; Respiratory Insufficiency ; Seizures ; Tachycardia ; Toxicology

OBJECTIVES: The use of anticholinergic drugs in the elderly may lead to negative events such as falls, delirium, urinary retention and cognitive decline, and the higher the number of anticholinergic drugs use, the more such negative events occur. This study aims to analyze the risk factors associated with the prescription of total anticholinergic drugs in elderly outpatients and evaluate the rationality of anticholinergic drugs, and to provide a reference for reducing the adverse effects of anticholinergic drugs. METHODS: A list of drugs with anticholinergic activity based on the Beers criteria was established. The basic information (such as age and gender), clinical diagnosis, and medications of elderly outpatient were extracted from hospital electronic medical records, and the Anticholinergic Cognitive Burden (ACB) Scale was used to calculate the anticholinergic burden for each patient. Logistic regression analysis was used to identify the potential risk factors for the occurrence of problems such as multiple medication and insomnia. RESULTS: A total of 1 840 prescriptions for elderly patients were reviewed. Of these patients, ACB score was more than or equal to 1 in 648 (35.22%) patients. Number of prescription medication (95% CI: 1.221 to 1.336) and insomnia (95% CI: 3.538 to 6.089) were independent factors affecting ACB scores (both P<0.01). Medications for patients of ACB scores were most commonly treated with the central nervous system drugs (such as alprazolam and eszopiclone) and for the cardiovascular system drugs (such as metoprolol and nifedipine). CONCLUSIONS There is a high rate of ACB drugs use in geriatric patients, and the clinical focus should be on multiple medication prescriptions, especially on the central nervous system drugs (such as alprazolam and eszopiclone) and cardiovascular system drugs (such as metoprolol and nifedipine). The prescription review should be emphasized to reduce adverse reactions to anticholinergic drugs in elderly patients.
Humans ; Aged ; Cholinergic Antagonists/adverse effects* ; Outpatients ; Metoprolol ; Alprazolam ; Eszopiclone ; Nifedipine ; Sleep Initiation and Maintenance Disorders ; Risk Factors

OBJECTIVETo study the correlation between the absorption rate constants of beta-adrenoreceptor antagonists in rat small intestinal segments and their molecular structural parameters.

METHODSThe net atomic charges and the molecular volumes of 11 beta-adrenoreceptor antagonists were obtained with the semiempirical self-consistent field molecular orbital calculation CNDO/2 method and Mont Carlo method respectively, using the minimum energy conformation obtained from the optimization of the standard molecular geometry with the molecular mechanics MM+ method. The stepwise multiple regression analysis was used to obtain the correlation equations.

RESULTSThe absorption rate constants of beta-adrenoreceptor antagonists in rat jejunum or ileum were well linearly correlated with the sum of the net charges of all hydrogen atoms and the molecular volumes. The beta-adrenoreceptor antagonist with higher lipophilicity, weaker hydrogen-bonding potential,and smaller molecular volume had greater absorption rate constants.

CONCLUSIONThe absorption rate constants of beta-adrenoreceptor antagonists in rat small intestinal segments are mainly related with their lipophilicity,hydrogen-bonding potential and molecular size.

Adrenergic beta-Antagonists ; chemistry ; pharmacokinetics ; Animals ; Intestinal Absorption ; Intestine, Small ; metabolism ; Metoprolol ; pharmacokinetics ; Molecular Structure ; Nadolol ; pharmacokinetics ; Propranolol ; pharmacokinetics ; Rats ; Regression Analysis

Animals ; Arrhythmias, Cardiac ; chemically induced ; prevention & control ; Cats ; Endothelin-1 ; adverse effects ; Medulla Oblongata ; drug effects ; Metoprolol ; pharmacology ; gamma-Aminobutyric Acid ; pharmacology

OBJECTIVETo investigate the effects of metoprolol on electrophysiology of ischemic and anoxic myocardium in diabetic rats.

METHODSForty Sprague-Dawley (SD) rats were divided into 4 groups: diabetes group; diabetes and ablation of left sympathetic nerve group; diabetes and metoprolol group and sham group. The diabetes model was induced by intraperitoneal injection of streptozotocin (STZ, 60 mg/kg). The ventricular diastolic effective threshold (DET), effective refractive period (ERP), and Ventricular fibrillation threshold (VFT) were measured. The serum concentration of nerve growth factor (NGF) was measured.

RESULTSMetoprolol increased DET of ischemic and anoxic myocardium in diabetic rats. The ablation of the left sympathetic nerve increased VFT of diabetic rats. VFT in metoprolo group was significantly increased compared to diabetes group after ischemia. The concentrations of NGF in diabetic group and metoprolol group were higher than those in sham group. There were no difference in NGF levels between ablation of left sympathetic nerve group and sham group.

CONCLUSIONThe remodeling of sympathetic nerve affects the electrophysiology of ischemic myocardium of diabetic rats. Metoprolol can increase the VFT and decrease the excitation threshold of the ischemic myocardium in diabetic rats.

Animals ; Diabetes Mellitus, Experimental ; physiopathology ; Heart ; drug effects ; physiopathology ; Male ; Metoprolol ; pharmacology ; Myocardial Ischemia ; physiopathology ; Nerve Growth Factor ; blood ; Rats ; Rats, Sprague-Dawley ; Sympathectomy