β-Blockers and ACE inhibitors synergistically aggravate anaphylaxis at least partly by decreasing the threshold of MC activation.
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Depletion of intracellular ATP with antimycin A has been shown to inhibit the internalization of several types of receptors, including beta adrenergic and muscarinic acetylcholine receptors. The effects of antimycin A treatment on conversion of beta and alpha-1 adrenergic receptors to a form exhibiting low apparent affinity for agonists in assays with intact cells were investigated, because conversion to the low-affinity form has been postulated to result from receptor internalization. Treatment of DDT1 MF-2 hamster smooth muscle cells with antimycin A greatly decreased conversion of beta adrenergic receptors to the form exhibiting low affinity for agonists. Binding of antagonists to intact cell beta adrenergic receptors was not altered by antimycin A. In contrast to the results with beta adrenergic receptors, conversion of alpha-1 adrenergic receptors to the low-affinity form was not inhibited by antimycin A. These results are consistent with the possible involvement of receptor internalization in conversion to the low affinity form for beta adrenergic receptors. They also provide further evidence that different mechanisms may be involved in conversion to the low-affinity form or in the internalization pathway in the case of alpha-1 adrenergic receptors.
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To assess efficacy and safety of selective beta-adrenoblockers (BAB) metoprolol succinate and nebivolol in patients with arterial hypertension (AH) and/or IHD associated with bronchoobstructive syndrome (BOS).
The aim of this study was to determine the incidence and significance of second- or third-degree heart block among patients with inferior myocardial infarction treated with thrombolytic therapy.
The purpose of this study was to examine the external predictability of an in vitro-in vivo correlation (IVIVC) for a metoprolol hydrophilic matrix extended-release formulation, with an acceptable internal predictability, in the presence of a range of formulation/manufacturing changes. In addition, this report evaluated the predictability of the IVIVC for another formulation of metoprolol tartrate differing in its release mechanism. Study 1 examined the scale up of a matrix extended-release tablet from a 3-kg small batch (I) to a 50-kg large batch (II). The second study examined the influence of scale and processing changes [3-kg small batch with fluid bed granulation and drying (III); 80-kg large batch with high shear granulation and microwave drying (IV), and a formulation with an alternate release mechanism formulated as a multiparticulate capsule (V)]. In vitro dissolution of all formulations (I-V) was conducted with a USP apparatus I at pH 6.8 and 150 rpm. Subjects received the metoprolol formulations, and serial blood samples were collected over 48 h and analyzed by a validated HPLC assay using fluorescence detection. A previously developed IVIVC was used to predict plasma profiles. Prediction errors (PE) were <10% for C(max) and area under the curve (AUC) of concentration versus time for I, II, and IV. The C(max) for III was slightly underestimated (11.7%); however, the PE of the AUC was <10%. Formulation V displayed a PE for C(max) > 20% and an AUC within 5% of observed values. The low PEs for C(max) and AUC observed for I-IV strongly suggest that the metoprolol IVIVC is externally valid, predictive of alternate processing methods (IV), scale-up (II, III), and allows the in vitro dissolution data to be used as a surrogate for validation studies. However, the lack of predictability for V supports the contention that IVIVCs are formulation specific.
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An overview of the current pharmacotherapy of central vestibular syndromes and the most common forms of central nystagmus as well as cerebellar disorders is given. 4-aminopyridine (4-AP) is recommended for the treatment of downbeat nystagmus, a frequent form of acquired persisting fixation nystagmus, and upbeat nystagmus. Animal studies showed that this non-selective blocker of voltage-gated potassium channels increases Purkinje cell excitability and normalizes the irregular firing rate, so that the inhibitory influence of the cerebellar cortex on vestibular and deep cerebellar nuclei is restored. The efficacy of 4-AP in episodic ataxia type 2, which is most often caused by mutations of the PQ-calcium channel, was demonstrated in a randomized controlled trial. It was also shown in an animal model (the tottering mouse) of episodic ataxia type 2. In a case series, chlorzoxazone, a non-selective activator of small-conductance calcium-activated potassium channels, was shown to reduce the DBN. The efficacy of acetyl-DL-leucine as a potential new symptomatic treatment for cerebellar diseases has been demonstrated in three case series. The ongoing randomized controlled trials on episodic ataxia type 2 (sustained-release form of 4-aminopyridine vs. acetazolamide vs. placebo; EAT2TREAT), vestibular migraine with metoprolol (PROVEMIG-trial), cerebellar gait disorders (sustained-release form of 4-aminopyridine vs. placebo; FACEG) and cerebellar ataxia (acetyl-DL-leucine vs. placebo; ALCAT) will provide new insights into the pharmacotherapy of cerebellar and central vestibular disorders.
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Previous studies have compared the outcome between patients with and without a confirmed acute myocardial infarction (AMI) mainly during the first few years after its onset. Our aim was to compare the prognosis between patients with and without a confirmed AMI during 10 years of follow-up. Patients participating in an early intervention trial with metoprolol in suspected AMI between 1976 and 1981 took part in this evaluation. The total 10-year mortality rate including hospital mortality was 51% for patients with confirmed AMI as compared with 32% for patients with a possible AMI and 23% for patients in whom AMI was definitely ruled out (p < 0.001). The 10-year mortality after discharge from hospital was in AMI 46%, possible AMI 32% and in definitely ruled out AMI 23% (p < 0.001). When simultaneously considering age, sex, previous history of cardiovascular disease and smoking, the development of AMI appeared as an independent predictor of death (p < 0.001). Thus, among patients hospitalized due to suspected AMI, 10-year mortality after discharge from hospital was directly related to the diagnosis during the first 3 days in hospital.
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Rate-reducing treatment with diltiazem or verapamil preserved exercise capacity and reduced levels of NT-proBNP compared with baseline, whereas treatment with metoprolol or carvedilol reduced the exercise capacity and increased levels of NT-proBNP.
Hemodynamic effects of m--nifedipine (m--Nif) combined with metoprolol (Met) were studied in conscious rabbits with impedance cardiography. Administration of m--Nif by intravenous injection (20 micrograms/kg) or by intraduodenal route (0.25 mg/kg) increased cardiac index (CI) and reduced total peripheral resistance (TPR) and arterial pressure. Intravenous injection of Met significantly slowed heart rate without great change in other hemodynamic parameters in conscious rabbits. Combination of m--Nif with Met gained the advantages of both m--Nif and Met. The negative effects of Met on CI and TPR were balanced by the vasodilatory effect of m--Nif. The difference between the results of m--Nif combined with equal dose of Met or with five times the dose of Met was just that further decrease of heart rate was observed. These results suggest that combined administration of m--Nif with Met may be more beneficial than giving each drug alone. It may be more suitable to use m--Nif combined with low doses of Met in order to avoid the danger of depressing myocardium.
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MPD but not MTP blocked IL-1β-induced CGRP release from cultured trigeminal cells. PGE2-stimulated CGRP release from trigeminal ganglia cell culture was not affected by pre-stimulation whether with MPD or MTP.
To investigate the effect of a nonselective β-blocker (propranolol) and cardioselective β-blocker (metoprolol) on wound healing in rats using incision and excision wound models and to compare the effect of these drugs on wound healing.
The influence of various beta-blockers on tear production in rabbits was studied by means of direct cannulation of the lacrimal gland excretory duct. Tear production was significantly decreased (p less than 0,001) after systemic (I.M.) administration of either selective beta 1-blockers (metoprolol, betaxolol), B2-selective (butoxamine) or non-selective ones (timolol, propranolol) or finally those with I.S.A. (oxprenolol), although differences in the size of tear production decreasing response of each beta-blocker were recorded. Bilateral topical application of timolol (50 microliters of 0,5% b.i.d. for three days), decreased also tear production significantly, while the response of betaxolol administered under the same regime was rather negligible. It is concluded that although beta 2 adrenergic receptors are mainly involved in tear production, the administration of selective beta 1-blockers in high doses disappears their selectivity, decreasing tear production too.
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The thirty minute renal ischemia appears to have determined the alterations found in the renal function and histology in both groups. Metoprolol, used in G2, as to the time and dose applied didn't protect the kidney from the ischemic episode.
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The effect of treatment for 1--4 weeks with metoprolol, a beta 1-selective blocking agent, or alprenolol, on the heart rate and blood pressure response to isometric exercise was studied in two groups of 12 patients with angina. Measurements were made during the peak effect of metoprolol 10, 40 or 50 mg, and alprenolol 200 mg as Aptin Durules. After 1 min of sustained handgrip at 50% of maximal voluntary contraction, systolic (6--15%) and diastolic (8--12%) blood pressure after both drugs was significantly lower than without any beta-blockade; Heart rate was decreased by 19--22% by metroprolol but not by alprenolol. The blood pressure rise during handgrip was not attenuated by either drug. The rise in heart rate was significantly reduced (by 36--50%) by metoprolol 40 and 50 mg and alprenolol 200 mg. No patient experienced angina during handgrip. In contrast, all but one were restricted by angina during bycycle exercise without treatment, at a level that produced the same increase in heart rate as the handgrip test, vis. 3 min at a load of 33 W). The cardiovascular response to sustained handgrip is too small to provide a useful challenge for determinatin of the anti-anginal efficacy of drugs. However, slight ECG changes of ischaemia did occur during handgrip, which were reversed by beta-blockade.
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We previously showed that Qiliqiangxin (QL) capsules could ameliorate cardiac hypertrophy and remodeling in a mouse model of pressure overload. Here, we compared the effects of QL alone with those of QL combined with the following 3 types of antihypertensive drugs on cardiac remodeling and dysfunction induced by pressure overload for 4 weeks in mice: an angiotensin II type 1 receptor (AT1-R) blocker (ARB), an angiotensin-converting enzyme inhibitor (ACEI), and a β-adrenergic receptor (β-AR) blocker (BB). Adult male mice (C57B/L6) were subjected to either transverse aortic constriction or sham operation for 4 weeks, and the drugs (or saline) were orally administered through gastric tubes. Cardiac function and remodeling were evaluated through echocardiography, catheterization, histology, and analysis of hypertrophic gene expression. Cardiomyocyte apoptosis and autophagy, AT1-R and β1-AR expression, and cell proliferation-related molecules were also examined. Although pressure overload-induced cardiac remodeling and dysfunction, hypertrophic gene reprogramming, AT1-R and β1-AR expression, and ERK phosphorylation were significantly attenuated by QL alone, QL + ARB, QL + ACEI, and QL + BB, the attenuation was stronger in the combination treatment groups. Moreover, apoptosis was reduced to a larger extent by each combination treatment than by QL alone, whereas autophagy was more strongly attenuated by either QL + ARB or QL + ACEI. None of the treatments significantly upregulated ErbB2 or ErbB4 phosphorylation, and none significantly downregulated C/EBPβ expression. Therefore, the effects of QL on chronic pressure overload-induced cardiac remodeling may be significantly increased when QL is combined with an ARB, an ACEI, or a BB.
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The aims of this study were to study the efficacy and tolerability of felodipine extended release (ER) 5 mg and metoprolol controlled release (CR/ZOC) 50 mg given as a fixed combination (Logimax) or as a free combination in elderly (age greater than 60 years) hypertensive patients, using ambulatory blood pressure (BP) monitoring. A secondary aim was to relate the efficacy of the free and fixed combinations with pharmacokinetic profiles.
Included were patients with a history of migraine with or without aura for at least 2 years. Excluded were persons with contraindications against treatment with beta blockers, chronic pain syndromes, pregnancy or previous experience with acupuncture or beta-blocking agents. A total of 85 patients were included; 77 completed the study.
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Our goal was to establish and validate a modified cocktail approach including probe drugs caffeine, chlorzoxazone, mephenytoin, metoprolol, and midazolam for simultaneous phenotyping of CYP1A2, CYP2E1, CYP2C19, CYP2D6, and CYP3A.
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To conduct a meta-analysis on the effect of CYP2D6 polymorphism on the pharmacokinetics and pharmacodynamics of metoprolol.
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This review has evaluated the Biopharmaceutics Classification System (BCS) and improvements have been proposed. The BCS has a very strict solubility/dissolution limit, a generous P(e)-limit (> or = 14-times higher rate constant limit for dissolution than for permeation), and is stricter for drugs with a long half-life (t(1/2)). Available human in-vivo, in-vitro, and in-silico P(e)-methods cannot classify P(e) for moderately to highly permeable substances sufficiently well, and in-vitro data often underpredict the in-vivo dissolution potential and rate. Good in-vivo dissolution and absorption can be expected for most high P(e) drug products. It has not been possible to find a highly permeable product with a Dose number (D(o)) < 385 (< 2400 in the fed state) that is clearly incompletely absorbed, and near complete uptake has been shown for a drug product with a D(o) of 660000. The potential implication of these findings is that many true BCS Class I drug products are incorrectly classified. This could be a reason for the limited use of this system. On this basis, it has been suggested that: the limit for high for solubility/dissolution is decreased (to > 40 and > 95% dissolved within 30 min and 3 h, respectively); the limit for high P(e) is increased (to >P(e) of metoprolol); accurate P(e)-models or in-vivo fraction absorbed data are used; solubility/dissolution tests are performed using real or validated simulated gastrointestinal fluids; in-vitro/in-vivo dissolution relationships are established; the t(1/2) is considered; and the rate-limiting step for in-vivo absorption is determined. A major change could be to reduce the BCS into two classes: permeation-rate (Class I) or dissolution-rate (Class II) limited absorption. It is believed that this could give a better balance and increase the number of biowaivers.
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The influence of nifedipine, verapamil, diltiazem, metoprolol, and enalapril on the basal and angiotensin II (Ang II)-induced elevation of [3H]thymidine incorporation into vascular smooth muscle cell (VSMC) DNA was examined. Our results from four independent experiments, each performed in triplicate, are summarized by calculating the half-maximal inhibitory concentration (IC50) of the drugs. Nifedipine, verapamil, and diltiazem had IC50 values of 2.3 +/- 0.7 x 10(-6), 3.5 +/- 0.3 x 10(-6), and 6.6 +/- 2.8 x 10(-6) M, respectively. Metoprolol had an IC50 value of 49 +/- 16 x 10(-6) M, whereas enalapril was completely ineffective. All drugs used had no influence on the basal cell [3H]thymidine incorporation. This in vitro study allows one to conclude that the calcium-entry blockers can inhibit the Ang II-induced cell growth and thus may have beneficial effects on the development and regression of vascular growth, which is associated with the pathogenesis of cardiovascular diseases.