Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0012833 (dizziness)
 9,689 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

During the intervening years since metoprolol was first reviewed in the Journal (1977), it has become widely used in the treatment of mild to moderate hypertension and angina pectoris. Although much data have accumulated, its precise mechanisms of action in these diseases remain largely uncertain. Optimum treatment of hypertension and angina pectoris with metoprolol is achieved through dose titration within the therapeutic range. It has been clearly demonstrated that metoprolol is at least as effective as other beta-blockers, diuretics and certain calcium antagonists in the majority of patients. Although a twice daily dosage regimen is normally used, satisfactory control can be maintained in many patients with single daily doses of conventional or, more frequently, slow release formulations. Addition of a diuretic may improve the overall response rate in hypertension. Several controlled trials have studied the effects of metoprolol administered during the acute phase and after myocardial infarction. In early intervention trials a reduction in total mortality was achieved in one moderately large trial of prolonged treatment, but in another, which excluded patients already being treated with beta-blockers or certain calcium antagonists and where treatment was only short term, mortality was significantly reduced only in 'high risk' patients. Overall results with metoprolol have not demonstrated that early intervention treatment in all patients produces clinically important improvement in short term mortality. Thus, the use of metoprolol during the early stages of myocardial infarction is controversial, largely because of the requirement to treat all patients to save a small number at 'high risk'. This blanket coverage approach to treatment may be more justified during the post-infarction follow-up phase since it has been shown that metoprolol slightly, but significantly, reduces the mortality rate for periods of up to 3 years. Metoprolol is generally well tolerated and its beta 1-selectivity may facilitate its administration to certain patients (e.g. asthmatics and diabetics) in whom non-selective beta-blockers are contraindicated. Temporary fatigue, dizziness and headache are among the most frequently reported side effects. After a decade of use, metoprolol is well established as a first choice drug in mild to moderate hypertension and stable angina, and is beneficial in post-infarction patients. Further study is needed in less well established areas of treatment such as cardiac arrhythmias, idiopathic dilated cardiomyopathy and hypertensive cardiomegaly.
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PMID:Metoprolol. An updated review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy, in hypertension, ischaemic heart disease and related cardiovascular disorders. 294 80

The antihypertensive effects of oral labetalol, a new alpha- and beta-adrenergic blocking agent, and metoprolol, a relatively beta1 selective adrenergic blocker, were evaluated in 91 patients with mild to moderate hypertension (standing diastolic blood pressure of 90 to 115 mm Hg) in a double-blind parallel group multicenter clinical trial. The effects of the two drugs on plasma lipids and lipoprotein fractions were also assessed. Following a four-week placebo phase, 44 patients were randomized to receive labetalol and 47 metoprolol. During a four-week titration phase, the labetalol dose was increased from 100 mg twice daily to a maximum of 600 mg twice daily to achieve a standing diastolic blood pressure of 90 mm Hg that was decreased by 10 mm Hg or more. Metoprolol was titrated from 50 mg to 200 mg twice daily. An eight-week maintenance period followed during which hydrochlorothiazide could be added. At the end of the maintenance phase, the doses of labetalol and metoprolol were tapered over a two to four day period after which patients received a placebo for one week. Blood pressure in the supine and standing position was measured at each visit. Labetalol and metoprolol both significantly (p less than 0.01) lowered the supine and standing blood pressure from baseline with no significant difference found between the two treatment groups. Both drugs lowered the heart rate; however, the rate-lowering effect was significantly greater with metoprolol (p less than 0.01). There were no significant effects of either drug on plasma lipids or lipoprotein fractions. Fatigue was the most frequently reported complaint with both drugs. Dizziness, dyspepsia, and nausea were more common with labetalol; bradycardia was more common with metoprolol. There was no blood pressure "overshoot" after withdrawing drug treatment; however, a heart rate "overshoot" was seen after metoprolol was tapered off and stopped. Labetalol is as safe and effective as metoprolol in the treatment of patients with mild to moderate hypertension.
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PMID:Multiclinic comparison of labetalol to metoprolol in treatment of mild to moderate systemic hypertension. 635

The cardioselective betablocking agent metoprolol was used to treat 21 outpatients with essential arterial hypertension graded 1 and 2 of the OMS scale. The treatment was given orally for a mean duration of nine weeks at doses of 100 mg/day for two weeks and 200 mg/day for the remaining time. The treatment caused a significant reduction of systolic and diastolic arterial pressure (p less than 0.001), both in the erect and the lying down position. The heart rate was also significantly reduced both in the lying down (p less than 0.01) and the erect (p less than 0.05) positions. Metoprolol was shown to be effective and well tolerated as an antihypertensive agent; the treatment had to be interrupted in a single case because of dizziness, tiredness and dullness.
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PMID:[Metoprolol in the treatment of essential hypertension (author's transl)]. 720 75

Controlled clinical trials, performed in more than 16,000 patients to date, have consistently shown the beneficial effects of long-term beta-blocker therapy in patients with chronic heart failure. However, it is not clear whether this represents a class effect or it is specific only to some agents. Beneficial effects on the prognosis of the patients with mild to moderate heart failure have been shown with metoprolol, bisoprolol, and carvedilol. However, these beta-blockers differ in their pharmacological characteristics. Metoprolol and bisoprolol are selective for beta 1-adrenergic receptors and are devoid of ancillary properties. Carvediol, at doses of 50 mg daily, blocks all beta 1-, beta 2-, and alpha 1- adrenergic receptors, and has associated antiproliferative and antioxidant activities. These differences cause a different acute hemodynamic response with a reduction in cardiac output and a tendency to a rise in pulmonary wedge pressure with selective agents and no change in cardiac output and a slight decrease in pulmonary pressures with carvedilol. Accordingly, when the therapy is started, the most frequent side effects are worsening heart failure with metoprolol and bisoprolol and hypotension and dizziness with carvedilol. It is still controversial whether these differences may also influence the long-term effects of therapy. Differently from selective beta-blockers, carvedilol does not upregulate beta 1-receptors, blocks all adrenergic receptors, decreases cardiac norepinephrine release, thus providing a more comprehensive blockade of the cardiac adrenergic drive. These properties have caused a larger increase in LV function and a lack of improvement in maximal exercise capacity with carvedilol, compared to selective beta-blockers. It is however, unclear whether these differences may also influence the patients' outcome.
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PMID:[New and old beta-blockers in the treatment of heart failure]. 1188 45

Controlled clinical trials performed in more than 13 000 patients have, to date, consistently shown the beneficial effects of long term beta-adrenoceptor antagonist (beta-blocker) therapy in patients with chronic heart failure. It is not clear whether this represents a class effect or whether it is specific only to some agents. Beneficial effects on the prognosis of patients with mild to moderate heart failure have been shown with metoprolol, bisoprolol, and carvedilol. These beta-blockers, however, differ in their pharmacologic characteristics. Metoprolol and bisoprolol are selective for beta(1)-adrenergic receptors and are devoid of ancillary properties. Carvedilol, at a dosage of 50 mg/day, blocks all beta(1)-, beta(2)-, and alpha(1)-adrenergic receptors, and it has associated antiproliferative and antioxidant activities. These differences cause a varied acute hemodynamic response, with a reduction in cardiac output and a tendency toward a rise in pulmonary wedge pressure with selective agents and no change in cardiac output and a slight decrease in pulmonary pressures with carvedilol. Accordingly, when the therapy is started, the most frequent adverse effects are worsening heart failure with metoprolol and bisoprolol, and hypotension and dizziness with carvedilol. It remains controversial whether these differences also influence the long term effects of therapy. Carvedilol may provide a more comprehensive blockade of the cardiac adrenergic drive than selective beta-blockers because it does not upregulate beta(1)-adrenergic receptors, blocks all adrenergic receptors and decreases cardiac norepinephrine release. These properties may lead to a larger increase in left ventricular function and a lack of improvement in maximal exercise capacity with carvedilol, compared with selective beta-blockers. It is, however, unclear whether these differences also influence patient outcome. The long term effects of different beta-blockers on prognosis are currently being compared in the Carvedilol or Metoprolol European Trial (COMET) in which more than 3000 patients with chronic heart failure have been randomized in a 1 : 1 ratio to receive metoprolol or carvedilol.
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PMID:Beta-blockade in heart failure: selective versus nonselective agents. 1472 47

Metoprolol has not yet been systematically studied in terms of quality of life and incidence of adverse drug reactions (ADRs). Metoprolol is metabolized by polymorphic CYP2D6, therefore poor CYP2D6 metabolizers may be at higher risk of ADRs. Therefore, it is to be proven whether genotyping is useful to guide initial dose selection. In the ongoing UNAMET study, nonrandomized out-patients start treatment with metoprolol for various disorders. With the use of standard questionnaires, the patients are prospectively evaluated for common ADRs (headache, dizziness, tiredness, sleep disturbances, dyspnea, cold extremities, sexual dysfunction) and quality of life. The questionnaires are filled out before and until 6 weeks after initiating therapy; blood pressure and heart rate are also measured. The acquired data are then related to the patients' metoprolol dose and plasma concentrations, as well as to their metabolic ratio of metoprolol/alpha-OH-metoprolol and CYP2D6 genotype.
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PMID:[Rationale and methods of the UNAMET study (dose- and CYP2D6-genotype-dependent adverse drug reactions of metoprolol)--a contribution to quality improvement in pharmacotherapy]. 1564 32

Mahaim fiber tachycardia is an uncommon cause of palpitations among the pediatric population. This case report describes an adolescent female who presented with recurrent episodes of tachycardia with chest pain and dizziness. Her ECG showed tachycardia with wide QRS complexes and left bundle branch block pattern. Repeat ECG after adenosine treatment revealed sinus rhythm with persistence of the left bundle branch block pattern. Metoprolol was started however she continued to have episodes of sustained tachycardia.Electrophysiologic study then confirmed the diagnosis of Mahaim fiber tachycardia. Treatment was successful with mapping of the accessory pathways followed by radiofrequency ablation.
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PMID:Unusual source of tachycardia in an adolescent. 2146 64