Carvedilol, but not metoprolol, was associated with a significant increase in CsA levels after initiation in cardiac transplant recipients. Although carvedilol and CsA do not interact at the level of cytochrome P450 system, it appears that carvedilol influences CsA levels through its effects on P-gp. An average reduction of 10% is necessary on the CsA dose upon initiation of carvedilol, and close follow-up of the level is essential.
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Both office blood pressures and the numbers of attacks of angina pectoris and symptoms all decreased obviously in the two groups after treatment. Blood pressures were reduced from 137.12/84.36 mm Hg to 131.80/77.68 mm Hg in Metoprolol group, and also reduced from 137.72/83.92 mm Hg to 129.56/78.76 mm Hg in Verapamil group (P>0.05, compared between the two groups). In both the Verapamil and Metoprolol groups, heart rates decreased, SDNN (standard deviation of all normal to normal RR intervals) and HRVTI (HRV indexes of time-domain) both increased significantly after treatment (P>0.05). And HRV indexes of low-frequency(LF), high-frequency (HF) and total power (TP) were increased obviously, while the low-to high-frequency ratio (LF/HF), very-low-frequency (VLF) were remarkably lower(P<0.05). Compared with Verapamil group, the changes of frequency-domain indexes in Metoprolol group were significant(P<0.05).
Compared with placebo metoprolol CR/XL produced a significant decrease in heart rate by 11 beats/min at rest and 18 beats/min at peak exercise. There was a tendency for a temporal decline in peak VO(2) after 3 months of therapy in both groups, but altogether peak VO(2) remained unchanged from baseline with no difference between the groups at 1 year.
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In this study, we characterized the interactions of arbutamine, a novel catecholamine developed for use as a cardiac stress testing agent, with different adrenergic receptor subtypes in vitro. These effects were compared with those of isoproterenol. In the electrically stimulated left atria of rats, arbutamine increased contractile force. The pD2 values (- log of the dose that produces 50% of the maximal responses) for arbutamine and isoproterenol were 8.45 +/- 0.15 and 8.55 +/- 0.02, respectively. Metoprolol shifted the concentration-effect curves for both isoproterenol and arbutamine to the right with a pA2 value (- log of the dose of the antagonist that reduces the maximal responses of an agonist to 50%) of 7.22-7.5. Both arbutamine and isoproterenol increased the rate of spontaneously beating rat right atria with pD2 values of 9.0 +/- 0.19 and 8.82 +/- 0.18, respectively. The affinity constants (KA) of arbutamine and isoproterenol for cardiac beta1-adrenergic receptors, as determined by competition binding assays, were found to be 7.32 and 6.04, respectively. In guinea pig trachea, arbutamine and isoproterenol produced a concentration-dependent relaxation that was blocked by propranolol. Their pD2 values were 7.9 +/- 0.1 and 8.2 +/- 0.1, respectively. Arbutamine contracted isolated rat aortic rings with a maximal increase of 38.1 +/- 6.7% that of 10 microM of norepinephrine. In rat white adipocytes, arbutamine, isoproterenol, and BRL-37344 stimulated glycerol release, with the order of potency being BRL-37344 > arbutamine > isoproterenol. In hamster brown adipocytes, the order was arbutamine > isoproterenol > BRL-37344. Moreover, arbutamine stimulated beta3-adrenergic receptors in guinea pig ileum. In conclusion, arbutamine is a novel catecholamine with similar potency and efficacy to that of isoproterenol. It stimulates cardiac beta1-, tracheal beta2-, and adiopocyte beta3-adrenergic receptors. Arbutamine does not stimulate alpha-adrenergic receptors at concentrations that were high enough to maximally activate the beta-adrenergic receptors.
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Beta adrenergic receptor antagonists (beta-Blockers) are frequently prescribed medications in the United States and have been identified in European municipal wastewater effluent, however no studies to date have investigated these compounds in United States wastewater effluent. Municipal wastewater effluent was collected from treatment facilities in Mississippi, Texas, and New York to investigate the occurrence of metoprolol, nadolol, and propranolol. Propranolol was identified in all wastewater samples analyzed (n = 34) at concentrations < or = 1.9 microg/l. Metoprolol and nadolol were identified in > or = 71% of the samples with concentrations of metoprolol < or = 1.2 microg/l and nadolol < or = 0.36 microg/l. Time course studies at both Mississippi plants and the Texas plant indicate that concentrations of propranolol, metoprolol, and nadolol remain relatively constant at each sampling period. This study indicates that beta-Blockers are present in United States wastewater effluent in the ng/l to microg/l range.
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Patients with nonischemic cardiomyopathy who have higher left ventricular inotropic reserve and normal RVEF derive higher increase in LVEF from beta-blocker therapy.
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Elevated BNP levels, by inducing sympathetic overdrive and altering Ca(2+) handling, promote adverse cardiac remodelling and VAs, which could account in part for the progression of HF after MI. The early use of β-blockers to prevent the deleterious effects of chronic BNP exposure may be beneficial in HF.
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Extended (72-hour) ambulatory electrocardiographic monitoring was used to enable time series analysis of heart rate and asymptomatic ST-segment depression in 9 patients with severe coronary artery disease. The effects of beta 1-adrenergic blockade with optimal dose metoprolol were then assessed. Data were analyzed using Fourier transformation, autocorrelation and cross-correlation to examine possible coupling between heart rate and ischemic electrocardiographic changes. A marked circadian pattern was observed for both heart rate and ambulatory myocardial ischemia, with a period of approximately 24 hours by both Fourier and autocorrelation methods. Cross-correlation revealed heart rate and ischemia to be tightly coupled with a lag of 0 hours during placebo. During beta 1 adrenergic blockade the marked circadian variation in heart rate was diminished, although some periodicity in the 24-hour region remained. Ambulatory ischemia was also markedly diminished during beta 1-adrenergic blockade; however, some residual ischemia remained that was characterized by a peak spectral activity shifted to a period of 5 to 7 hours. Heart rate and ischemia were not coupled during beta 1-adrenergic blockade, as evidenced by lack of significant cross-correlation. Thus, time series analysis suggests close coupling between the variation in heart rate and ambulatory ischemia in patients with severe coronary artery disease. Beta 1-adrenergic blockade can markedly alter the periodic characteristics of and coupling between heart rate and ischemia. Ischemia remaining during beta 1-adrenergic blockade may have different spectral characteristics than that predominating during placebo administration. These differences may be manifestations of the heterogenous pathophysiologic mechanisms responsible for ambulatory ischemia and may have therapeutic implications.
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Three Veterans Administration (VA) databases with information from hospitals and clinics in Iowa and Nebraska. Patients. A total of 8390 veterans with a diagnosis of asthma or COPD receiving treatment with a beta-blocker or another cardiovascular agent.
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The results of this study demonstrate that chronotropic support of the transplanted heart using a rate-responsive pacemaker, with activity-based sensors programmed for maximal sensitivity, improves both peak heart rate and exercise capacity in heart transplant recipients significantly more than circulating catecholamines alone.
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Beta-blockers (metoprolol, bisoprolol, and carvedilol) are a cornerstone of heart failure (HF) treatment. However, it is well recognized that responses to a beta-blocker are variable among patients with HF. Numerous studies now suggest that genetic polymorphisms may contribute to variability in responses to a beta-blocker, including left ventricular ejection fraction improvement, survival, and hospitalization due to HF exacerbation. This review summarizes the pharmacogenetic data for beta-blockers in patients with HF and discusses the potential implications of beta-blocker pharmacogenetics for HF patients.
Rats were administered (intraperitoneally 200 mg/kg/day) stevioside as aqueous solution or physiological saline in the course of 5 days, then anaesthetized with urethane and the first ECG recording was made. The prepared jugular vein was connected to an infusion pump with adrenaline (0.1 mg/mL), verapamil (2.5 mg/mL) or metoprolol (1 mg/mL). Control animals, pretreated with saline, in addition to the mentioned drugs, were also infused with the solution of stevioside (200 mg/mL) in the course of recording ECG.
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To assess the predictive value of general practice electronic prescribing records with respect to adherence to long-term medications as compared to claims-based pharmacy dispensing data.
The hepatic pharmacokinetics of five selected basic drugs with different physicochemical properties were studied in IPRL from control rats and rats with RHF. Hepatic pharmacokinetic modelling was performed with a two-phase physiologically-based organ pharmacokinetic model with the vascular space and dispersion evaluated with the MID technique. The liver damage arising from RHF was assessed by changes in liver biochemistry and histopathology. The expression of various CYP isoforms was evaluated by real-time RT-PCR analysis.
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In the present study, a multi-residue method based on a bag-solid phase extraction (bag-SPE) technique was evaluated for determination of 10 pharmaceuticals in surface water close to the effluent of a sewage treatment plant (STP) and along a coastal gradient from a STP effluent. The 10 compounds selected were caffeine, atenolol, metoprolol, oxazepam, carbamazepine, ketoprofen, naproxen, ibuprofen, diclofenac and gemfibrozil. All analyses were performed using ultra-performance liquid chromatography (UPLC) combined with quadrupole time-of-flight (QTOF) mass spectrometry. The detection limits (LOD) ranged from 1.0 to 13 ng L(-1). The method showed linear concentration ranges from 25 to 800 ng L(-1) with regression coefficients (R(2)) better than 0.9801. The recoveries of the selected analytes ranged from 11 to 65% with relative standard deviations (RSD) of <16% and inter-day variations of less than 18%. Isotopically labeled surrogate standards were used to compensate for sampling losses and matrix effects. Four of the selected 10 pharmaceuticals (caffeine, metoprolol, oxazepam and carbamazepine) were quantified, at concentrations ranging from 4 to 210 ng L(-1).
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Beta blocker treatment may worsen glucose metabolism.
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Unbound IC(50) (IC(50,u)) values of 15 drugs were determined in eight recombinantly expressed human cytochromes P450 (P450s) and human hepatocytes, and the data were used to simulate clinical area under the plasma concentration-time curve changes (deltaAUC) on coadministration with prototypic CYP2D6 substrates. Significant differences in IC(50,u) values between enzyme sources were observed for quinidine (0.02 microM in recombinant CYP2D6 versus 0.5 microM in hepatocytes) and propafenone (0.02 versus 4.1 microM). The relative contribution of individual P450s toward the oxidative metabolism of clinical probes desipramine, imipramine, tolterodine, propranolol, and metoprolol was estimated via determinations of intrinsic clearance using recombinant P450s (rP450s). Simulated deltaAUC were compared with those observed in vivo via the ratios of unbound inhibitor concentration at the entrance to the liver to inhibition constants determined against rP450s ([I](in,u)/K(i)) and incorporating parallel substrate elimination pathways. For this dataset, there were 20% false negatives (observed deltaAUC >or= 2, predicted deltaAUC < 2), 77% correct predictions, and 3% false positives. Thus, the [I](in,u)/K(i) approach appears relatively successful at estimating the degree of clinical interactions and can be incorporated into drug discovery strategies. Using a Simcyp ADME (absorption, metabolism, distribution, elimination) simulator (Simcyp Ltd., Sheffield, UK), there were 3% false negatives, 94% correct simulations, and 3% false positives. False-negative predictions were rationalized as a result of mechanism-based inhibition, production of inhibitory metabolites, and/or hepatic uptake. Integrating inhibition and reaction phenotyping data from automated rP450 screens have shown applicability to predict the occurrence and degree of in vivo drug-drug interactions, and such data may identify the clinical consequences for candidate drugs as both "perpetrators" and "victims" of P450-mediated interactions.
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The purpose of this study was to develop a method to prepare Metoprolol Succinate (MS) sustained release pellets and compress them into pellet-containing tablets without losing sustained release property. The drug layered pellets were coated with Eudragit NE 30D to obtain a sustained release (SR) property. The mechanical properties and permeability of the coating film were tailored by adjusting the proportion of talc in the coating dispersion and the weight gain of the coating film. Pellets with different MS release rates were tested and then mixed together by different ratios to optimize drug release rate. The mixed pellets were compressed into tablets with cushioning excipients. The results showed that when the ratio of talc and coating material was 1:4, the coating operation could be conducted successfully without pellet conglutination and the mechanical property of the coating film was enhanced to withstand the compress force during tableting. Blending SR-coated pellets of 20% weight gain with SR-coated pellets of 40% weight gain at the ratio of 1:5 could produce a constant and desired drug release rate. The formulation and the procedure developed in the study were suitable to prepare MS pellet-containing tablets with selected SR properties.
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The fixed combination consistently provides fairly constant and effective felodipine and metoprolol concentrations after once-daily administration of one tablet. It is clinically interchangeable with the free combination of metoprolol CR/ZOK tablets and felodipine ER tablets. Finally, felodipine and metoprolol do not interact on a pharmacokinetic level when administered as the fixed combination.
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Aim of the study was to assess effect of therapy with b-adrenoblockers and If-inhibitors on the rate of development of coronary complications of carotid endarterectomy. Patients (n=111, mean age 61 +/- 4 years) subjected to carotid endarterectomy in 2006 - 2007 were divided into 3 groups according to therapy in pre-, intra-, and postoperative period. Group 1 consisted of 48 patients treated with metoprolol. Group 2 comprised 33 patients with contraindications to b-adrenoblockers who were treated with If-inhibitor ivabradine. Patients of control group 3 (n=30) received neither b-adrenoblocker nor If-inhibitor. There were no significant differences between groups in sex, age, concomitant pathology, and degree of stenosis of operated carotid artery. We assessed rate of development of ischemia and myocardial infarction during operation and in first 24 hours after surgery. In group 1 mean 24 hour heart rate according to Holter ECG monitoring after 7 days of therapy decreased by 14 +/- 3,7 beats/min, episodes of ischemia after surgery were registered in 4 patients (8%). In group 2 mean 24 hour heart rate decreased by 10 +/- 2,5 beats/min, 4 patients (12%) had signs of myocardial ischemia during first 24 hours after surgery. There were no myocardial infarctions in groups 1 and 2. In control group mean 24 hour heart rate did not significantly change. Significantly higher number of postoperative coronary complications was revealed among patients of this group: 2 (6%) developed myocardial infarctions, in 5 (17%) appeared signs of myocardial ischemia. Administration of b-adrenoblocker metoprolol and If-inhibitor ivabradine significantly lowers rate of development of coronary complications after carotid endarterectomy. Ivabradine is indicated to patients with contra indications to b-adrenoblockers.
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Minoxidil is very effective in the treatment of severe or resistant hypertension but fluid retention and hypertrichosis have been side-effects. This study examines the suggestion that the use of small doses of minoxidil may be effective in the treatment of moderate hypertension without causing these adverse effects. Sixteen patients with an elevated blood pressure level that was suboptimally controlled by combination therapy with diuretic and beta-adrenoreceptor blocking agents entered a randomized open trial to compare the efficacy and acceptability of minoxidil and prazosin as supplementary therapy to bendrofluazide and metoprolol. Blood pressure control was similar in the two groups. However, relatively large doses of minoxidil were required and over-all tolerance to the drug was poor; five of eight patients who were receiving minoxidil experienced marked fluid retention that necessitated a change in diuretic agent to substantial doses of frusemide. Low doses of minoxidil do not appear to be effective in the treatment of moderate hypertension, and the drug cannot be recommended for this indication.