CE coupling with end-column electrochemiluminescence detection for chiral separation of disopyramide

CE with electrochemiluminescence (ECL) detection technique was successfully applied for the chiral separation of a kind of class IA antiarrhythmic racemic drug. To the best of our knowledge, this is the first report of ECL detection used in chiral CE. To get better detection sensitivity and good enantioresolution at the same time, the conditions of capillary inlet and outlet buffer were systematically optimized. Unlike the traditional chiral separation method, the buffers we used in the capillary inlet and outlet differed from each other in terms of buffer pH, ionic strength, type of BGE as well as buffer composition. Under the optimum conditions, baseline enantioseparation and highly sensitive detection of the enantiomers were achieved. Wide linear relationship of each enantiomer was achieved in the range of 5 x 10(-7) to 2 x 10(-5) mol/L with relative coefficients of 0.996 and 0.997, respectively. The detection limits were estimated to be 8 x 10(-8) and 1.0 x 10(-7) mol/L (S/N = 3) for the enantiomers, respectively. In addition, a successful application of this new method to the chiral separation of the racemic drug in spiked plasma samples confirmed the validity and applicability of the chiral CE-ECL method.

Swelling studies and in vitro release of verapamil from calcium alginate and calcium alginate–chitosan beads

The aim of the present work was to investigate the swelling behavior and the in vitro release of the antihypertensive drug verapamil hydrochloride from calcium alginate and chitosan treated calcium alginate beads. Calcium-alginate beads, chitosan-coated alginate beads and alginate-chitosan mixed beads were synthesized and their morphology was investigated by scanning electron microscopy. The swelling ability of the beads in different media was found to be dependent on the presence of the polyelectrolyte complex between alginate and chitosan, the pH of the aqueous media and the initial physical state of the beads. The results revealed that the encapsulation of verapamil in both calcium-alginate and calcium alginate-chitosan mixed beads exceeded 80%. Considering the in vitro stability of verapamil encapsulating beads, 70% of the drug released from wet and dry plain calcium alginate beads within 1 and 3h, respectively. The presence of chitosan was found to retard significantly the release from wet beads. However, in the case of dry beads the presence of chitosan had no significant effect on the initial release stage and significantly increased the release on the later stage. The results were analyzed by using a semi-empirical equation and it was found that the drug release mechanisms were either "anomalous transport" or "case-II transport".

Level A in vitro-in vivo Correlation (IVIVC) Model with Bayesian Approach to Formulation Series

In vitro-in vivo correlation (IVIVC) models for formulation series are useful in drug development, but the current models are limited by their inability to include data variability in the predictions. Our goal was to develop a level A IVIVC model that provides predictions with probabilities. The Bayesian approach was used to describe uncertainty related to the model and the data. Three bioavailability studies of levosimendan were used to develop IVIVC model. Dissolution was tested at pH 5.8 with basket. The IVIVC model with Bayesian approach consisted of prior and observed data. All observed data were fitted to the one-compartment model together with prior data. Probability distributions of pharmacokinetic parameters and concentration time profiles were obtained. To test the external predictability of IVIVC model, only dissolution data of formulations E and F were used. The external predictability was good. The possibility to utilize all observed data when constructing IVIVC model, can be considered as a major strength of Bayesian approach. For levosimendan capsule data traditional IVIVC model was not predictable. The usefulness of IVIVC model with Bayesian approach was shown with our data, but the same approach can be used more widely for formulation optimization and for dissolution based biowaivers.

The Novel Antiarrhythmic Drug Dronedarone: Comparison with Amiodarone

Dronedarone is a noniodinated benzofuran derivative that has been developed to overcome the limiting iodine-associated adverse effects of the commonly used antiarrhythmic drug, amiodarone. It displays a wide cellular electrophysiological spectrum largely similar to amiodarone, inhibiting the potassium currents I(Kr), I(Ks), I(KI), I(KACh), and I(sus), as well as sodium currents and L-type calcium currents in isolated cardiomyocytes. In addition, dronedarone exhibits antiadrenergic properties. In vivo, dronedarone has been shown to be more effective than amiodarone in several arrhythmia models, particularly in preventing ischemia- and reperfusion-induced ventricular fibrillation and in reducing mortality. However, an increased incidence of torsades de pointes with dronedarone in dogs shows that possible proarrhythmic effects of dronedarone require further evaluation. The clinical trails DAFNE, EURIDIS, and ADONIS indicated safety, antiarrhythmic efficacy and low proarrhythmic potential of the drug in low-risk patients. In contrast, the increased incidence of death in the dronedarone group of the discontinued ANDROMEDA trial raises safety concerns for patients with congestive heart failure and moderate to severe left ventricular dysfunction. Dronedarone appears to be effective in preventing relapses of atrial fibrillation and atrial flutter. Torsades de pointes, the most severe adverse effect associated with amiodarone, has not yet been reported in humans with dronedarone. Unlike amiodarone, dronedarone had little effect on thyroid function and hormone levels in animal models and had no significant effects on human thyroid function in clinical trials. In conclusion, dronedarone could be a useful drug for prevention of atrial fibrillation and atrial flutter relapses in low-risk patients. However, further experimental studies and long-term clinical trials are required to provide additional evidence of efficacy and safety of dronedarone.

Antiarrhythmic activity of 4,6-di(het)aryl-5-nitro-3,4-dihydropyrimidin-(1H)-2-ones and its effects on arterial pressure in rats

The antiarrhythmic activity of 4,6-di(het)aryl-5-nitro-3,4-dihydropyrimidin-(1H)-2-ones toward two types of experimental rat arrhythmia has been studied. With CaCl(2) induced arrhythmia model, several agents have demonstrated high antiarrhythmic activity and the lack of influence on arterial pressure of rats.

Role of 1,4-benzothiazine derivatives in medicinal chemistry

1,4-Benzothiazine (1,4-BT) derivatives have been reported to exhibit a wide range of pharmacological properties including antifungal, immunostimulating, anti-aldoso-reductase, anti-rheumatic, anti-allergic, vasorelaxant, anti-arrhythmic, anti-hypertensive, neuroprotective and cytotoxic activities. These different effects indicate that 1,4-BT is a template potentially useful in medicinal chemistry research and therapeutic applications.

Flavonoids from ChineseViscum coloratum: antiarrhythmic efficacy and ionic mechanisms

Viscum coloratum flavonoids (VCF) have been demonstrated to produce a variety of biological actions. An accumulating line of evidence supported the view that VCF may exert protective effects on the cardiovascular system. The aim of the study was to assess the antiarrhythmic activity as well as the electrophysiological properties of VCF. The antiarrhythmic effects of VCF were observed in a rat model of arrhythmia induced by aconitine. VCF significantly and dose-dependently increased the dosage of aconitine required to induce the arrhythmia indexes. Electrophysiological experiment revealed that VCF shortened APD through inhibition of ICa-L.

[Comparative study of the antiarrhythmic activity of magnesium aspartate L-, D- and DL-aspartate stereoisomers]

It seems an established fact that magnesium (Mg) aspartate is effective in prophylaxis and adjuvant therapy of cardiac arrhythmia (e.g. prevention of toxic symptoms during therapy with digoxin). There are claims that L-aspartate salts are better delivery forms for cations such as Mg than D-aspartate salts, and Mg L-aspartate can be more beneficial in the treatment of several forms of primary Mg deficiency than Mg DL- and D-aspartate. Therefore, the purposes of the present work were to compare of antiarrhythmic action of Mg L-, D- and DL-aspartate stereoisomers using CaCl(2)- and aconitine-induced arrhythmia models in rats. It was found that intravenously administered Mg L-aspartate exhibited higher activity compared to Mg D- and DL-aspartate in calcium chloride and aconitine-induced arrhythmias. In rats with arrhythmias induced by calcium chloride Mg L-aspartate compared with Mg D-aspartate and Mg DL-aspartate produced greater decrease of incidence of arrhythmias, increase of time first arrhythmia onset, decrease of percentage of rats that died and increase of duration of life after onset of first arrhythmia. In rats with aconitine-induced arrhythmia Mg L-aspartate surpassed Mg D-aspartate and Mg DL-aspartate in parameters of acute toxicity (LD(50)), effective dose (ED(50)) and antiarrhythmic (therapeutic) ratio (LD(50)/ED(50)).

Drug Binding Interactions in the Inner Cavity of hERG Channels: Molecular Insights from Structure-Activity Relationships of Clofilium and Ibutilide Analogs

Block of human ether-a-go-go related gene (hERG) K(+) channels by otherwise useful drugs is the most common cause of long QT syndrome, a disorder of cardiac repolarization that predisposes patients to potentially fatal arrhythmias. This undesirable long QT side effect has been a major reason for the withdrawal of medications from the pharmaceutical market. Understanding the molecular basis of hERG block is therefore essential to facilitate the design of safe drugs. Binding sites for hERG blockers have been mapped within the inner cavity of the channel and include aromatic residues in the S6 helix (Tyr-652, Phe-656) and residues in the pore helix (Thr-623, Ser-624, Val-625). We used mutagenesis of these residues, combined with an investigation of hERG block by close analogs of clofilium and ibutilide, to assess how specific alterations in drug structure affected potency and binding interactions. Although changing the basic nitrogen from quaternary to tertiary accelerated the onset of block, the IC(50) and kinetics for recovery from block were similar. In contrast, analogs with different para-substituents on the phenyl ring had significantly different potencies for wild-type hERG block. The highest potency was achieved with polar or electronegative para-substituents, whereas neutral para-substituents had potencies more than 100-fold lower. Results from mutagenesis and molecular modeling studies suggest that phenyl ring para-substituents influence drug interactions with Thr-623, Ser-624, and Tyr-652 and strongly affect binding affinity. Together, these findings suggest that modifying the para-substituent could be a useful strategy for reducing hERG potency and increasing the safety margin of compounds in development.

Drug therapy for atrial fibrillation: where do we go from here?

Atrial fibrillation, the most common cardiac arrhythmia requiring medical attention, has effects that range from mild symptoms to devastating stroke. Although treatments have evolved since the foxglove plant (later identified as containing digitalis) was first administered to slow the heart rate, satisfactory drug therapy has not been developed. In this review we describe present-day medical options and developments of future therapies to treat atrial fibrillation and maintain normal sinus rhythm.

Synthesis of Biologically Active Amines via Rhodium−Bisphosphite-Catalyzed Hydroaminomethylation

[reaction: see text] We report the use of a highly regioselective rhodium-bisphosphite catalyst for olefin hydroaminomethylation. This catalyst system was successfully applied in the synthesis of two biologically active tertiary amines, ibutilide and aripiprazole.

Preparation and Evaluation of Verapamil Hydrochloride Microcapsules

Verapamil was encapsulated with ethylcellulose (EC) and cellulose acetate (CA) in various ratios of drug and polymer by the hot melt technique and the prepared microcapsules were evaluated for size range, drug content, drug release profiles, and kinetics of drug release. The microcapsules were compressed into tablets to study the variation of drug release between the 2 types of formulations (ie, microcapsules and tablets). The size analysis of prepared microcapsules was done by a standard sieving method and in vitro dissolution studies were carried out in USP XXI dissolution test apparatus in 0.1 N HCl as dissolution media to study the drug release profiles of the microcapsules. Scanning electron microscopy studies were carried out to investigate the surface characteristics of the microcapsules prepared from both type of polymers. Drug release profiles from the compressed non-disintegrating matrix tablets prepared from the microcapsules were also investigated. All the microcapsules were discrete, free flowing, and reproducible with respect to size distribution and drug content. Maximum percentage of the microcapsules belonged to the size range of 35/50. Drug release durations of VERCA1 (drug: CA 3:1), VERCA2 (drug: CA 2:1), and VERCA3 (drug: CA 1:1) microcapsules were extended up to 3, 5, and 6 hours, respectively, and those of VEREC1 (drug: EC 3:1), VEREC2 (drug: EC 2:1), and VEREC3 (drug: EC 1:1) microcapsules were extended up to 4, 5, and 7 hours, respectively. The microcapsules of both types having a drug:polymer ratio of 1:1 had the slowest release rate in their respective categories. The microcapsules were compressed into nondisintegrating matrix tablets. The hardness of the tablets was tested using the Monsanto Hardness Tester and was found to be 6-7 kg/cm. All the tablets contained the drug verapamil within 100% +/- 5%. The drug release data of both the microcapsules and tablets prepared were examined kinetically, and the ideal kinetic model was determined for the drug release. The tablets prepared by compressing the microcapsule formulations were more satisfactory in releasing the drug at a controlled and uniform rate following Higuchian kinetics and the formulations VCACRT3 and VECCRT3 were able to control release of drug up to 12 hours. Thus, it is possible to formulate a single-unit, controlled-release dosage form of verapamil for oral administration at least once every 12 hours using the polymers CA and EC.

Predictive models for hERG potassium channel blockers

We report here a general method for the prediction of hERG potassium channel blockers using computational models generated from correlation analyses of a large dataset and pharmacophore-based GRIND descriptors. These 3D-QSAR models are compared favorably with other traditional and chemometric based HQSAR methods.

Cardiac pacemaker I(f) current and its inhibition by heart rate-reducing agents

The 'funny' (I(f)) current, first described by Brown et al. in 1979 in pacemaker myocytes, is an inward current that slowly activates on hyperpolarization to the diastolic range of voltages. Extensive work has amply demonstrated its involvement in the generation of spontaneous activity. The extent of current activation determines the slope of diastolic depolarization and hence of pacemaker rate. Since I(f) is under cyclic adenosine monophosphate (cAMP)-mediated control by beta-adrenergic and muscarinic stimulation, this mechanism underlies neurotransmitter modulation of cardiac rate and is therefore of fundamental physiological relevance. Their key role in pacemaking makes f-channels a natural target for drugs aiming at regulation of pacemaker activity and cardiac rate. Both in the past and more recently, rate-reducing drugs that slow pacemaker activity by decreasing the rate of diastolic depolarization have been developed. These drugs act as specific f-channel inhibitors. One of the latest such molecules developed, ivabradine, has a highly specific inhibitory action on f-channels, which atypically depends on the current flow across the channel. These specific properties make the I(f) inhibition by ivabradine 'use-dependent,' a therapeutically beneficial property. Investigation of the interaction between rate-reducing molecules and specific regions of hyperpolarization-activated, cyclic nucleotidegated (HCN) channels, the molecular components of native f-channels, will provide new strategies for more specific and efficient drug design. This short review addresses the major basic properties of cardiac f-channels, with a focus on the mode of action of f-channel inhibitors and on its possible molecular interpretation.

Ibutilide – recent molecular insights and accumulating evidence for use in atrial flutter and fibrillation

Ibutilide is a 'pure' class III antiarrhythmic drug, used intravenously against atrial flutter and fibrillation. At a cellular level it exerts two main actions: induction of a persistent Na+ current sensitive to dihydropyridine Ca2+ channel blockers and potent inhibition of the cardiac rapid delayed rectifier K+ current, by binding within the channel pore cavity upon channel gating. Ibutilide has been shown to terminate atrial flutter and fibrillation in animal studies, with some risk of ventricular pro-arrhythmia. Experimental models of hypertrophy/heart failure show altered sensitivity to ibutilide, with increased dispersion of repolarisation and incidence of pro-arrhythmia. Patient trials show that ibutilide is effective at terminating atrial arrhythmias when given alone, and that it can increase effectiveness and reduce energy requirements of electrical cardioversion. The risk to patients of polymorphic ventricular tachycardia necessitates careful patient selection and monitoring during and after treatment. An ibutilide analogue, trecetilide, requires further investigation but may offer a less readily metabolised and pro-arrhythmic alternative to ibutilide.

Metabolism of antiarrhythmics

Antiarrhythmics are a group of drugs that manage the irregular electrical activity of the heart. Their use in the clinic is made difficult by their narrow therapeutic index. The disposition of antiarrhythmics is dependent on many factors, such as administration route, stereoselectivity in the first-pass effect, inhibition of enzymes, polymorphisms, etc. Consequently, the pharmacological activity of drugs may be interindividually variable. Experiments using organ homogenates or hepatic microsome fractions were used for simulating the biotransformation of the drug in vivo. The classical approaches, such as correlation analysis, specifically the inhibitory effect, or induction of chemicals, and immunoinhibition, may be combined with the use of recombinant enzymes for identifying the enzymes involved in the drug metabolism. The fate of the antiarrhythmics may also be investigated in live animals. A species-dependent metabolism was often observed. The pre-treatment with chemicals, which influences the change (inhibition or induction) in the drug disposition, may provide insights into the enzymes involved in vivo. However, published data indicated that the data obtained from animals should not be extrapolated directly to humans. Nevertheless, animal models are useful for investigating the mechanism of clinical observations. The clinical use of the antiarrhythmics becomes complex, when the drug metabolism is genetically/phenotypically dependent and active metabolites are formed. Furthermore, the stereoselectivity may also modify the disposition and the pharmacodynamic profile of a therapeutic agent. Only the knowledge of the drug metabolism and the status of each individual may allow the use of antiarrhythmics safely.

Effect of the antifibrillatory compound tedisamil (KC-8857) on transmembrane currents in mammalian ventricular myocytes

The cellular mechanism of action of tedisamil (KC-8857) (TED), a novel antiarrhythmic/antifibrillatory compound, was studied on transmembrane currents in guinea pig, rabbit and dog ventricular myocytes by applying the patch-clamp and the conventional microelectrode technique. In guinea pig myocytes the rapid component of the delayed rectifier potassium current (IKr) was largely diminished by 1 microM TED (from 0.88+/-0.17 to 0.23+/-0.07 pA/pF, n=5, p<0.05), while its slow component (IKs) was reduced only by 5 microM TED (from 8.1+/-0.3 to 4.23+/-0.07 pA/pF, n=5, p<0.05). TED did not significantly change the IKr and IKs kinetics. In rabbit myocytes 1 microM TED decreased the amplitude of the transient outward current (I(to)) from 20.3+/-4.9 to 13.9+/-2.8 pA/pF (n=5, p<0.05), accelerated its fast inactivation time constant from 8.3+/-0.6 to 3.5+/-0.5 ms (n=5, p<0.05) and reduced the ATP-activated potassium current (IKATP) from 38.2+/-11.8 to 18.4+/-4.7 pA/pF (activator: 50 microM cromakalim; n=5, p<0.05). In dog myocytes 2 microM TED blocked the fast sodium current (INa) with rapid onset and moderately slow offset kinetics, while the inward rectifier potassium (IK1), the inward calcium (ICa) and even the I(to) currents were not affected by TED in concentration as high as 10 microM. The differences in I(to) responsiveness between dog and rabbit are probably due to the different alpha-subunits of I(to) in these species. It is concluded that inhibition of several transmembrane currents, including IKr, IKs, I(to), IKATP and even INa, can contribute to the high antiarrhythmic/antifibrillatory potency of TED, underlying predominant Class III combined with I A/B type antiarrhythmic characteristics.

Dronedarone: an amiodarone analogue

Of the antiarrhythmic drugs in current use, amiodarone is one of the most effective and is associated with a comparatively low risk of drug-induced pro-arrhythmia, probably due to its multiple pharmacological actions on cardiac ion channels and receptors. However, amiodarone is associated with significant extra-cardiac side effects and this has driven development of amiodarone analogues. These analogues include short acting analogues (e.g., AT-2001) with similar acute effects to amiodarone, the thyroid receptor antagonist KB-130015 and dronedarone. Dronedarone, (SR-33589; Sanofi-Synthelabo), is a non-iodinated amiodarone derivative that inhibits Na +, K + and Ca 2+ currents. It is a potent inhibitor of the acetylcholine-activated K + current from atrial and sinoatrial nodal tissue, and inhibits the rapid delayed rectifier more potently than slow and inward rectifier K + currents and inhibits L-type calcium current. Dronedarone is an antagonist at alpha- and beta-adrenoceptors and unlike amiodarone, has little effect at thyroid receptors. Dronedarone is more potent than amiodarone in inhibiting arrhythmias and death in animal models of ischaemia- and reperfusion-induced arrhythmias. In the Dronedarone Atrial Fibrillation Study After Electrical Cardioversion (DAFNE) clinical trial, dronedarone 800 mg/day appeared to be effective and safe for the prevention of atrial fibrillation relapses after cardioversion. The Antiarrhythmic Trial with Dronedarone in Moderate-to-Severe Congestive Heart Failure Evaluating Morbidity Decrease (ANDROMEDA) trial was stopped due to a potential increased risk of death in the dronedarone group. Trials of dronedarone in the maintenance of sinus rhythm in patients with atrial fibrillation and a safety and tolerability study in patients with an implantable cardioverter defibrillator are ongoing. Further experimental and clinical studies are required before we have a definitive answer to whether dronedarone has advantages over amiodarone and other amiodarone analogues.

Two patterns of ion channelopathy in the myocardium: perspectives for development of anti-arrhythmic agents

Cardiac arrhythmia remains a significant problem, due to the high morbidity and mortality associated with cardiovascular diseases with prominent cardiac remodeling. There is still a lack of effective drugs with which to combat this life-threatening disorder. The abnormal electrophysiological properties of the heart can be explained in terms of ion channels and channelopathy and, in recent years, advances have been made in understanding these properties. There are two patterns of ion channelopathies in the diseased heart: Single insufficiency disorder, which is attributed to mutations in genes, and a multiple derangement of channels. Malignant arrhythmias in a diseased heart usually occur when ventricular hypertrophy is evident, and when they are associated with abnormal repolarization. Abnormalities in the ryanodine receptor-calcium release channel complex (RyR)2, FK-506 binding protein (FKBP 12.6), cardiac sarcoplasmic reticulum calcium ATPase (SERCA2a) and phospholamban (PLB) are involved in the initiation of cardiac arrhythmias, and can be identified as targets for therapeutic interventions.

Characterization of inward-rectifier K+ channel inhibition by antiarrhythmic piperazine

Strong inward-rectifier K(+) (Kir) channels play a significant role in shaping the cardiac action potential: they help produce its long plateau and accelerate its rate of repolarization. Consequently, genetic deletion of the gene encoding the strongly rectifying K(+) channel IRK1 (Kir2.1) prolongs the cardiac action potential in mice. In principle, broadening the action potential lengthens the refractory period, which may in turn be antiarrhythmogenic. Interestingly, previous studies showed that piperazine, an inexpensive and safe anthelmintic, both inhibits IRK1 channels and is antiarrhythmic in some animal preparations. This potential pharmacological benefit motivated us to further characterize the energetic, kinetic, and molecular properties of IRK1 inhibition by piperazine. We show how its blocking characteristics, in particular, its shallow voltage dependence, allow piperazine to be effective even in the presence of high-affinity polyamine blockers. We also examine the channel selectivity of piperazine and its molecular determinants.

In silico modelling--pharmacophores and hERG channel models

In computational drug design, modelling studies are undertaken following two main strategies that depend on which information is available. If experimental data exist only for the molecules displaying the biological property of interest, a so-called ligand-based approach is taken; if information is available on the macromolecular target(s) of the compounds (e.g. proteins' 3D structures), target-based studies can be carried out. Recently, in the field of hERG K+-channel blocking drugs, pharmacophoric (ligand-based) studies started appearing aimed at determining the physicochemical features associated with the channel block, and also at predicting the hERG blocking potential of compounds. However, partial homology models (target-based) of the hERG channel have also been built and used as working tools to interpret electrophysiological and mutagenesis studies. Here, we review some of the ligand- and target-based in silico studies carried out on hERG, focusing on both their main characteristics and their meaning. In addition, we discuss some methodological aspects of the computational work that in our opinion should be considered, in view of the construction of reliable models possibly able to predict the functional behaviour of the channel system and the blocking potential of drugs.

Mechanisms of photoinduced electron transfer reactions of lappaconitine with aromatic amino acids. Time-resolved CIDNP study

CIDNP techniques were applied to the investigation of the elementary mechanism of photoinduced interaction between anti-arrhythmic drug lappaconitine and amino acids tyrosine and tryptophan. It has been shown that the reactions involve the formation of lappaconitine radical anion. Lappaconitine radical anion is unstable and rapidly eliminates N-acetyl anthranilic acid via protonation and ether bond cleavage. The rate constant of ether bond cleavage was estimated to be equal to 4 x 10(5) s(-1). The role of single electron transfer is discussed in the light of the model of drug-receptor interactions.

Antiarrhythmic profile and endothelial action of novel decahydroquinoline derivatives

We tested antiarrhythmic and endothelial action of novel decahydroquinoline derivatives. Antiarrhythmic activity was analyzed using models of aconitine-, calcium chloride-, and adrenaline-induced arrhythmias in rats. Potency to induce nitric oxide (NO)-dependent coronary vasodilation was assessed in isolated guinea pig heart perfused according to Langendorff technique. Among 15 novel decahydroquinoline derivatives (D1-15), four of them displayed antiarrhythmic activity (D12-D15). D12-D15 compounds were more active in the model of aconitine-induced arrhythmias than in calcium chloride-induced arrhythmias and were inactive in the model of adrenaline-induced arrhythmias. Profile of antiarrhythmic activity of D12-D15 compounds was similar to that of quinidine and procainamide. Interestingly, in the isolated guinea pig heart D14 and D15 (10(-5) M) induced coronary vasodilation, that was mediated by endothelium-derived NO. In conclusion, novel decahydroquinoline derivatives described here (D12-D15) show antiarrhythmic activity typical of antiarrhythmic drugs of class I. Importantly, some of these compounds (D14, D15) release NO from coronary endothelium, which may provide an additional therapeutic benefit.