Drugs online research references
Am Heart J. 1988 Jul;116(1 Pt 1):44-9.
Hemodynamic effects of intravenous metoprolol in acute myocardial infarction: the role of anatomic subsets in predicting patient response.
Breisblatt WM, Waldo DA, Burns MJ, Spaccavento LJ.
Cardiology Section, Wilford Hall USAF Medical Center, Lackland Air Force Base, Texas.
The acute effects of intravenous metoprolol were evaluated in 30 patients with myocardial infarction by means of serial hemodynamic and radionuclide measurements of left ventricular function. Within 1 hour of completion of the metoprolol dosing, 90% of the patients underwent cardiac catheterization to define anatomy and to assess patients for interventional therapy; the remainder had catheterization by 72 hours. All patients tolerated intravenous metoprolol without significant side effects. Patient responses to therapy were divided into two groups based on the angiographic findings. At catheterization, all group 1 patients had visible collaterals to or a patent vessel supplying the vascular distribution of the infarction. All group 2 patients had occluded coronary arteries without evidence of collaterals to the infarct zone. Group 1 (n = 13) improved both systolic and diastolic left ventricular function (mean ejection fraction [EF] = 46% to 55%, peak filling rate [PFR] = 2.1 to 3.2 Edv/sec), while group 2 (n = 17) patients were unchanged (EF = 43% to 42%, PFR = 2.0 to 1.9). Patient characteristics and time to treatment were similar in both groups, as were the hemodynamic effects of metoprolol. Heart rate decreased 20% in group 1 and 22% in group 2 and cardiac output fell 22% in group 1 and 32% in group 2. Acute improvement in ventricular function in these patients appears to be closely related to the coronary anatomy, and in those with flow to the infarct zone, intravenous metoprolol may be effective in preserving left ventricular function.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2839972&dopt=Abstract
Am J Cardiol. 1979 Nov;44(6):1195-200.
Hemodynamic effects of intravenous metoprolol.
Bourdillon PD, Canepa-Anson R, Rickards AF.
The hemodynamic effects of the cardioselective beta adrenergic blocking agent metoprolol, at a dose of 0.1 mg/kg body weight administered intravenously, were studied in 10 patients undergoing routine cardiac catheterization. The beta adrenergic blocking effect of the drug was confirmed by a highly significant reduction (53 percent, P less than 0.001) in the mean heart rate response to a challenge with isoproterenol, and by a mean heart rate rssponse to a challenge with isoproterenol, and by a highly significant reduction (73 percent, P less than 0.001) in the isoproterenol-induced increase in the first derivative of left ventricular pressure (dP/dt). An intrinsic negative inotropic effect was shown by a 43 percent reduction (P less than 0.05) in the response of mean left ventricular dP/dt when the heart rate was fixed by atrial pacing alone. With the combination of atrial pacing and isoproterenol, metoprolol produced a 48 percent reduction (P less than 0.01) in the response of mean left ventricular dP/dt, resulting from both the intrinsic depressor effect and the beta adrenergic blocking effect on the rate-independent beta agonist activity of isoproterenol. There was no significant change in right atrial, femoral arterial or left ventricular end-diastolic pressure; analysis of left ventricular angiograms performed during atrial pacing before and after metoprolol revealed no significant effect on angiographic ejection fraction, pressure-volume loops or diastolic compliance. In two patients improvement in segmental wall motion was noted, and no deterioration was seen in any patient. Metoprolol is an effective cardioselective beta adrenergic blocking agent that, under these conditions, reduces catecholamine-induced increases in heart rate and left ventricular dP/dt without significant alteration in ejection fraction, preload or afterload.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=495515&dopt=Abstract
Farmaco. 1995 Apr;50(4):281-4.
Spectrophotometric investigation of metoprolol-benzyl orange reaction and its application to the assay in pharmaceutical dosage forms.
Vujic Z, Radulovic D, Zivanovic L.
Institute of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Belgrade, Serbia.
A sensitive spectrophotometric method for the determination of metoprolol tartrate in tablets and ampoules is presented. Using spectrophotometric measurements, it was found that metoprolol tartrate and benzyl orange form a chloroform soluble ion-pair complex with an absorption maximum at 401 nm. The composition of the ion-pair complex was determined by applying Job's method to equimolar solutions of metoprolol tartrate: benzyl orange (1:2); molar absorptivity 7.39 x 10(3) mol-1 cm-1. Extraction of the ion-pair complex in chloroform was accomplished easily at a Britton-Robinson's buffered optimum pH = 5.2, mu = 0.1 mol/dm3. The relative stability constant, calculated according to the method of Sommer and Job's non-equimolar solutions, was log K = 9.72 (avg. value). Beer's law was obeyed up to 3.42 micrograms/ml of metoprolol tartrate (the detection limit was also 3.42 micrograms/ml). The precision of the method was checked at three different concentrations. The RSD (n = 7) varied from 0.51 to 2.03%. Reproducibility was examined by analysing Lopresor tablets and ampoules. Recoveries varied from 99-101%. The reported method, applied to the assay of metoprolol tartrate in tablets and ampoules, gives precise and reproducible results.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7669173&dopt=Abstract
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