Search results for "Anti-Arrhythmia Agents"
showing 10 items of 34 documents
Amiodarone pulmonary toxicity
2004
The amount of literature on amiodarone pulmonary toxicity (APT) peaked in 1983-1984 with several hundred cases reported cumulatively, and declined thereafter. Since the mid-1990s, publications have increased, which suggests that APT remains a current problem in clinical practice. Amiodarone remains difficult to diagnose noninvasively, and although the outcome is good in the majority of patients, not all cases of APT can be controlled satisfactorily.
Biowaiver monographs for immediate release solid oral dosage forms: quinidine sulfate.
2009
Literature data are reviewed relevant to the decision to allow a waiver of in vivo bioequivalence (BE) testing for the approval of new multisource and reformulated immediate release (IR) solid oral dosage forms containing quinidine sulfate. Quinidine sulfate's solubility and permeability, its therapeutic use and index, pharmacokinetics, excipient interactions and reported BE/bioavailability (BA) problems were taken into consideration. The available data are not fully conclusive, but do suggest that quinidine sulfate is highly soluble and moderately to highly permeable and would likely be assigned to BCS Class I (or at worst BCS III). In view of the inconclusiveness of the data and, more imp…
Metabolism of propafenone and verapamil by cryopreserved human, rat, mouse and dog hepatocytes: comparison with metabolism in vivo
2003
In the present study we examined the metabolism of [(14)C]propafenone (P) and [(14)C]verapamil (V) using cryopreserved human, dog (Beagle), rat (Sprague-Dawley) and mouse (NMRI) hepatocytes. The percentage ratios of the metabolites were identified after extraction by HPLC with UV and radioactivity detection. Phase-II metabolites were cleaved using beta-glucuronidase. Metabolism of the drugs by cryopreserved hepatocytes was compared with that in the respective species in vivo. All phase-I and -II metabolites known from in vivo experiments: 5-hydroxy-P (5-OH-P); 4'-hydroxy-P (4'-OH-P); N-despropyl-P (NdesP) and the respective glucuronides, were identified after incubation with cryopreserved h…
Vomilenine Reductase — a novel Enzyme catalyzing a crucial Step in the Biosynthesis of the Therapeutically applied Antiarrhythmic Alkaloid Ajmaline
2002
Delineation of the biochemical pathway leading to the antiarrhythmic Rauvolfia alkaloid ajmaline has been an important target in biosynthetic research for many years. The biosynthetic sequence starting with tryptamine and the monoterpene secologanin consists of about 10 different steps. Most of the participating enzymes have been detected and characterized previously, except those catalyzing the reduction of the intermediate vomilenine. A novel NADPH-dependent enzyme that reduces the intermediate has been isolated from Rauvolfia serpentina cell suspension cultures. Vomilenine reductase (M(r )43 kDa, temp opt 30 degrees C, pH opt 5.7-6.2), saturates the indolenine double bond of vomilenine w…
Polymorphism and solvates of flecainide base
2013
Flecainide base is pharmaceutically active substance used for production of flecainide acetate which is known in market as Tambacor, Almarytm, Apocard, Ecrinal or Flecaine. It is determined that flecainide base forms four polymorphic forms abbreviated as Ib, IIb, IIIb and IVb. Flecainide base form Ib is thermodynamically stable form at laboratory temperature while form IIIb is stable at higher temperatures. Flecainide form Ib absorbs water in its structure between layers and forms non-stoichiometric hydrate. Flecainide base binds with organic solvents and form monosolvates. Flecainide base form Ib crystallizes in orthorhombic crystals with lattice parameters a = 27.88 Å, b = 13.78 Å, c = 9.…
Effect of chronic exercise and ATP-sensitive potassium channel blockade on the spectral characteristics evolution of ventricular fibrillation in acut…
2013
Purpose: It has been proposed that chronic exercise produces a KATP channel blockade in ischemic myocardium. We have also reported that channel blockade and training exert very similar effects on energy required to defibrillate. In fact it is postulated that one mechanism by which exercise exerts an antiarrhythmic effect, is by blocking KATP channel. We have analyzed the evolution of spectrum characteristics of ventricular fibrillation (VF), in normoxic conditions and after acute myocardial ischemia, in isolated hearts from trained rabbits, and in hearts submitted to KATP channel blockade. Our hypothesis is that the spectrum characteristics of VF evolve similarly in trained hearts and in he…
Dofetilide effects on the inhibition by trains of subthreshold conditioning stimuli.
2004
We investigated the electrophysiological actions of dofetilide upon the ventricular myocardium to determine whether the drug modifies the inhibitory effects of subthreshold stimuli trains upon ventricular refractoriness. In nine Langendorff perfused rabbit hearts, ventricular epicardial electrodes were used to determine the following parameters at baseline and during dofetilide perfusion (0.5 micromolar): effective (ERP) and functional (FRP) refractory periods, conduction velocity (CV), wavelength (WL), and ERP prolongation (inhibitory effect) induced by subthreshold stimuli trains (STr) at pulse frequencies of 100, 300, and 600 Hz. Dofetilide significantly prolongs ventricular refractorine…
[Effect of flecainide on longitudinal and transverse conduction velocities in ventricular myocardium. An experimental study].
2007
It is known that the effect of flecainide on longitudinal and transverse ventricular conduction velocities depends on the coupling interval. If this is so, whether the longitudinal or transverse direction is predominantly affected could depend on the magnitude of the coupling interval. In order to investigate this hypothesis, we studied the effect of flecainide, 1 micromol/L, on conduction velocities in excised heart preparations from 11 rabbits using a basal cycle length of 250 ms and inserting two extrastimuli at a decreasing coupling interval. Flecainide significantly reduced both conduction velocities. However, the effect increased as the coupling interval decreased for only the longitu…
The role of the renin-angiotensin system in atrial fibrillation and the therapeutic effects of ACE-Is and ARBS
2008
Atrial fibrillation (AF) is the most common rhythm disturbance in medical practice and represents a very expensive health problem. AF can be managed with the prevention of thromboembolism and either a rate control of rhythm strategy. As both strategies have important limitations, probably a preventative strategy in patients at risk of developing arrhythmia can be a more attractive option. The renin-angiotensin system (RAS) seems to be involved in the genesis of arrhythmia by the following two mechanisms: 1. the induction of atrial fibrosis and structural remodelling by mitogen-activated protein kinase (MAPK) expression and reduction of collagenase activity; 2. the induction of electrical re…
Pharmacological Therapy in Children with Atrial Fibrillation and Atrial Flutter
2008
Heart rhythm disorders in children are not different, on electrocardiographic trace, from heart rhythm disorders in adults with the exception of incidence which is different according to the age. Paticularly, atrial flutter (FlA) and fibrillation (FA) are very uncommon arrhythmias in the general pediatric population. Generally atrial fibrillation and atrial flutter, in our experience, is a temporary heart rhythm disturbance connected to specifical and resovable reasons with the exception of Fontains surgical correction of congenital heart diseases or cardiopathies with dilatation of both atria. Presenting symptoms, symptom history (e.g., frequency, duration, and severity), risk assessment, …