Dronedarone for the Treatment of Atrial Arrhythmias in Adults With Congenital Heart Disease

BACKGROUND

Atrial tachyarrhythmias are common and difficult to treat in adults with congenital heart disease. Dronedarone has proven effective in patients without congenital heart disease, but data are limited about its use in adults with congenital heart disease of moderate to great complexity.

METHODS

A single-center, retrospective chart review of 21 adults with congenital heart disease of moderate to great complexity who were treated with dronedarone for atrial tachyarrhythmias was performed.

RESULTS

The median (IQR) age at dronedarone initiation was 35 (27.5-39) years. Eleven patients (52%) were male. Ten patients (48%) had New York Heart Association class I disease, 10 (48%) had class II disease, and 1 (5%) had class III disease. Ejection fraction at initiation was greater than 55% in 11 patients (52%), 35% to 55% in 9 patients (43%), and less than 35% in 1 patient (5%). Prior treatments included β-blockers (71%), sotalol (38%), amiodarone (24%), digoxin (24%), and catheter ablation (38%). Rhythm control was complete in 5 patients (24%), partial in 6 (29%), and inadequate in 10 (48%). Two patients (10%) experienced adverse events, including nausea in 1 (5%) and cardiac arrest in 1 (5%), which occurred 48 months after initiation of treatment. There were no deaths during the follow-up period. The median (IQR) follow-up time for patients with complete or partial rhythm control was 20 (1-54) months.

CONCLUSION

Dronedarone can be effective for adult patients with congenital heart disease and atrial arrhythmias for whom more established therapies have failed, and with close monitoring it can be safely tolerated.

Involvement of Mitochondrial Mechanisms and Cyclooxygenase-2 Activation in the Effect of Desethylamiodarone on 4T1 Triple-Negative Breast Cancer Line

Novel compounds significantly interfering with the mitochondrial energy production may have therapeutic value in triple-negative breast cancer (TNBC). This criterion is clearly fulfilled by desethylamiodarone (DEA), which is a major metabolite of amiodarone, a widely used antiarrhythmic drug, since the DEA previously demonstrated anti-neoplastic, anti-metastasizing, and direct mitochondrial effects in B16F10 melanoma cells. Additionally, the more than fifty years of clinical experience with amiodarone should answer most of the safety concerns about DEA. Accordingly, in the present study, we investigated DEA’s potential in TNBC by using a TN and a hormone receptor positive (HR+) BC cell line. DEA reduced the viability, colony formation, and invasive growth of the 4T1 cell line and led to a higher extent of the MCF-7 cell line. It lowered mitochondrial transmembrane potential and induced mitochondrial fragmentation. On the other hand, DEA failed to significantly affect various parameters of the cellular energy metabolism as determined by a Seahorse live cell respirometer. Cyclooxygenase 2 (COX-2), which was upregulated by DEA in the TNBC cell line only, accounted for most of 4T1’s DEA resistance, which was counteracted by the selective COX-2 inhibitor celecoxib. All these data indicate that DEA may have potentiality in the therapy of TNBC.

Amiodarone's major metabolite, desethylamiodarone inhibits proliferation of B16-F10 melanoma cells and limits lung metastasis formation in an in vivo experimental model

Previously, we demonstrated the in vitro anti-tumor effects of desethylamiodarone (DEA) in bladder and cervix cancer cell lines. In the present study, we intended to establish its potentiality in B16-F10 metastatic melanoma cells in vitro and in vivo. We assessed cell proliferation, apoptosis and cell cycle by using sulforhodamine B assay, Muse™ Annexin V & Dead Cell and Muse® Cell Cycle assays, respectively. We determined colony formation after crystal violet staining. For studying mechanistic aspects, immunoblotting analysis was performed. We used a C57BL/6 experimental lung metastasis model for demonstrating in vivo anti-metastatic potential of DEA. DEA inhibited in vitro proliferation and colony formation, and in vivo lung metastasizing properties of B16-F10 cells. It arrested the cells in G0/G1 phase of their cycle likely via p21 in a p53-dependent fashion, and induced caspase mediated apoptosis likely via inversely regulating Bcl-2 and Bax levels, and reducing Akt and ERK1/2 activation. In this study, we provided in vitro and in vivo experimental evidences for DEA’s potentiality in the therapy of metastatic melanomas. Since DEA is the major metabolite of amiodarone, a worldwide used antiarrhythmic drug, safety concerns could be resolved more easily for it than for a novel pharmacological agent.

DNA damage-induced apoptosis and mitogen-activated protein kinase pathway contribute to the toxicity of dronedarone in hepatic cells

Dronedarone, an antiarrhythmic drug, has been marketed as an alternative to amiodarone. The use of dronedarone has been associated with severe liver injury; however, the mechanisms remain unclear. In this study, the possible mechanisms of dronedarone induced liver toxicity were characterized in HepG2 cells. Dronedarone decreased cells viability and induced apoptosis and DNA damage in a concentration- and time-dependent manner. Pretreatment of the HepG2 cells with apoptosis inhibitors (caspase-3, -8, and -9) or the necrosis inhibitor (Necrox-5), partially, but significantly, reduced the release of lactate dehydrogenase. Dronedarone caused the release of cytochrome c from mitochondria to cytosol, a prominent feature of apoptosis. In addition, the activation of caspase-2 was involved in dronedarone induced DNA damage and the activation of JNK and p38 signaling pathways. Inhibition of JNK and p38 by specific inhibitors attenuated dronedarone-induced cell death, apoptosis, and DNA damage. Additionally, suppression of caspase-2 decreased the activities of JNK and p38. Dronedarone triggered DNA damage was regulated by downregulation of topoisomerase IIα at both transcriptional and post-transcriptional levels. Taken together, our data show that DNA damage, apoptosis, and the activation of JNK and p38 contribute to dronedarone-induced cytotoxicity. Environ. Mol. Mutagen. 59:278-289, 2018. © 2018 Wiley Periodicals, Inc.

Association between N-desethylamiodarone/amiodarone ratio and amiodarone-induced thyroid dysfunction

PURPOSE

We used a retrospective data mining approach to explore the association between serum amiodarone (AMD) and N-desethylamiodarone (DEA) concentrations and thyroid-related hormone levels.

METHODS

Laboratory data sets from January 2012 to April 2016 were extracted from the computerized hospital information system database at the National Cerebral and Cardiovascular Center (NCVC). Data sets that contained serum AMD and DEA concentrations and thyroid function tests, including thyroid-stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3), were analyzed.

RESULTS

A total of 1831 clinical laboratory data sets from 330 patients were analyzed. Data sets were classified into five groups (euthyroidism, hyperthyroidism, subclinical hyperthyroidism, hypothyroidism, and subclinical hypothyroidism) based on the definition of thyroid function in our hospital. Most abnormal levels of thyroid hormones were observed within the therapeutic range of serum AMD and DEA concentrations. The mean DEA/AMD ratio in the hyperthyroidism group was significantly higher than that in the euthyroidism group (0.95 ± 0.42 vs. 0.87 ± 0.28, p = 0.0209), and the mean DEA/AMD ratio in the hypothyroidism group was significantly lower than that in the euthyroidism group (0.77 ± 0.26 vs. 0.87 ± 0.28, p = 0.0038). The suppressed TSH group (0.98 ± 0.41 vs. 0.87 ± 0.28, p < 0.001) and the elevated FT4 level group (0.90 ± 0.33 vs. 0.84 ± 0.27, p = 0.0037) showed significantly higher DEA/AMD ratios compared with normal level groups. The elevated TSH group showed a significantly lower DEA/AMD ratio compared with the normal group (0.81 ± 0.25 vs. 0.87 ± 0.28, p < 0.0001).

CONCLUSIONS

High and low DEA/AMD ratios were associated with AMD-induced hyperthyroidism and hypothyroidism, respectively. The DEA/AMD ratio may be a predictive marker for AMD-induced thyroid dysfunction.

Bioanalytical Method Validation for Dronedarone and Duloxetine in Blood Serum

The present work relates to the development and validation of reversed-phase HPLC-UV-photodiode array methods for the estimation of two drugs in blood serum: dronedarone hydrochloride (DDN), a class III antiarrhythmic drug, and duloxetine hydrochloride (DLX), an antidepressant. Chromatographic analysis of DLX was carried out on a Nucleodur C18 column (250 × 4.6 mm, 5 μm) using ammonium acetate buffer (32 mM, pH 5.5) and acetonitrile (40 + 60, v/v; flow rate of 1.0 mL/min; detection wavelength of 290 nm) as the mobile phase. A Waters XTerra C18 column (250 × 4.6 mm, 5 μm) was used for the chromatographic analysis of DDN using an acetonitrile-ammonium formate buffer (20 mM, pH 3.0, with formic acid; 45 + 55, v/v; flow rate 1.0 mL/min) as the mobile phase. Pentazocine and bupropion HCl were used as the internal reference standards for DLX and DDN, respectively. Excellent linearity was observed for DLX (r2 = 0.9996; concentration range 0.2-10.0 μg/mL) and DDN (r2 = 0.9997; concn. range 2.0-50.0 μg/mL). The LODs for DLX and DDN were 0.022 and 0.78 μg/mL, respectively, and the LOQs 0.066 and 2.4 μg/mL, respectively.

Dronedarone: An Amiodarone Analog for the Treatment of Atrial Fibrillation and Atrial Flutter

Objective:

To review the pharmacology, pharmacokinetics, clinical efficacy, and safety profile of dronedarone for the treatment of atrial fibrillation.

Data Sources:

A literature search was conducted using the search terms dronedarone, SR 33589, atrial fibrillation, and antiarrhythmic medication in MEDLINE (1966–February 2007), International Pharmaceutical Abstracts (1970–February 2007), and EMBASE (1990–February 2007). References from the identified trials and selected review articles were evaluated. Additional information, including abstracts and posters, was obtained from Sanofi-Aventis.

Study Selection and Data Extraction:

Published studies and meeting abstracts evaluating the effects of dronedarone in humans and animals were reviewed.

Data Synthesis:

Dronedarone is a novel antiarrhythmic medication to treat atrial fibrillation. Dronedarone has a multifaceted mechanism of action similar to that of amiodarone. Dronedarone works by blocking potassium, sodium, and calcium channels and exhibits antiadrenergic properties. The drug has been evaluated at doses of 400, 600, and 800 mg twice daily. It prolonged the time to atrial fibrillation recurrence to 60–158 days compared with 5–59 days with placebo and decreased heart rate during atrial fibrillation by 12–25 beats/min in clinical trials. Major adverse events include gastrointestinal side effects and risk of proarrhythmia. Dronedarone may increase the risk of mortality in patients with congestive heart failure.

Conclusions:

Dronedarone is a new antiarrhythmic agent for the treatment of atrial fibrillation. Further studies are needed to better define dronedarone's safety profile and place in therapy.

Dronedarone: Basic Pharmacology and Clinical Use

Dronedarone is the newest antiarrhythmic drug approved for the maintenance of sinus rhythm in patients with nonpermanent atrial fibrillation (AF). It is a multi-channel blocker with diverse electrophysiologic properties. Dronedarone decreases the incidence of AF recurrence and the ventricular rate during recurrence. Dronedarone decreases rates of cardiovascular hospitalizations in patients with paroxysmal and persistent AF. Dronedarone increases mortality in patients with permanent AF and those with moderate-severe heart failure, and should thus be avoided in these populations. Dronedarone is less effective than amiodarone but also has less toxicity. Direct comparison with other antiarrhythmic drugs is not available.

Dronedarone and Amiodarone Induce Dyslipidemia and Thyroid Dysfunction in Rats

BACKGROUND/AIMS

Amiodarone, a thyroid hormone-like molecule, can induce dyslipidemia and thyroid dysfunction. However, the effects of dronedarone on lipid metabolism and of both dronedarone and amiodarone on thyroid function and lipid metabolism remain unknown.

METHODS

Fifty male Sprague-Dawley rats were randomly divided into 5 groups (10 in each group): normal control (NC), amiodarone-treated (AMT), dronedarone-treated (DRT), rats treated with amiodarone combined with polyene phosphatidylcholine (AC), and rats treated with dronedarone combined with polyene phosphatidylcholine (DC). Rats were given amiodarone (120 mg/kg/d), dronedarone (120 mg/kg/d), and polyene phosphatidylcholine (200 mg/kg/d) for 13 weeks. At the end of weeks 4, 8, 12, and 13, plasma-free triiodothyronine (FT3), free thyroxine (FT4), triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), and high-density lipoprotein cholesterol (HDL-c) were determined. At the end of this protocol, rats were sacrificed and the thyroid glands were isolated, weighed, and examined histopathologically. The protein expression of Bcl-2 was measured by immunochemical staining. The mRNA expression of thyroglobulin (Tg), type-1 deiodinase (D1), and thyroid peroxidase (TPO) were detected by polymerase chain reaction (PCR).

RESULTS

Compared with the NC group, FT3 and FT4 levels in the DRT and DC groups significantly increased at week 4 but declined thereafter. The AMT and AC groups had lower FT3 levels but comparable FT4 levels. The levels of TG, LDL-c, and HDL-c in the NC group were lower than those in the other groups whereas the LDL-c/HDL-c ratio was lowest in the AMT group. Bcl-2 expression significantly increased in the DRT group. The mRNA expression of Tg increased whereas the mRNA expression of D1 decreased. Dronedarone induced hyperthyroidism at the early stage and hypothyroidism at the late stage whereas amiodarone only caused hypothyroidism.

CONCLUSION

Both dronedarone and amiodarone can induce dyslipidemia and increase the levels of TC, LDL-c, and HDL-c, and these effects may be associated with thyroid dysfunction.

[AMIODARONE AND THE THYROID FUNCTION]

Amiodarone is a benzofuran derivative that contains up to 40% of iodine. Amiodarone is used for treatment and prevention of life threatening supraventricular and ventricular tachyarrhythmias. The effects on thyroid gland vary from abnormalities in thyroid function tests to overt amiodarone induced hypothyroidism (AIH) and thyrotoxicosis (AIT). Patients with AIH are treated with L-thyroxine and may continue treatment with amiodarone. Two different forms of AIT have to be distinguished: amiodarone induced hyperthyroidism (AIT I) and thyroiditis (AIT II). AIT I is treated with antithyroid drugs, while total thyroidectomy and iodine-131 are used for definitive treatment. AIT II is treated with glucocorticoids. Patients with AIT have to stop treatment with amiodarone. Dronedarone is a less potent antiarrhythmic agent with structural and pharmacological properties similar to amiodarone. Dronedarone is devoid of iodine with fewer adverse effects and therefore it may be used in high risk patients for development of AIT or AIH.

Organising pneumonia due to dronedarone

Organising pneumonia is one of the responses of the lung to injury and can mimic bacterial pneumonia but importantly it does not respond to antibiotic therapy. We present the case of a 67-year-old male who was diagnosed with organising pneumonia secondary to dronedarone. Drug reactions are a common cause and early identification of the culprit is mandatory to prevent further morbidity and ensure a favourable outcome. On chest radiography there may be fleeting peripheral consolidation, while computed tomography can show a range of stereotyped patterns including perilobular consolidation. Bronchoscopic biopsy may not always be possible but response to steroids is often rapid following removal of the culprit drug. Dronedarone should be included in the list of possible drugs and the Pneumotox database remains a useful resource for the clinician when acute drug-related pneumotoxicity is suspected.

Developing a list of high-alert medications for patients with chronic diseases

BACKGROUND

Patients with chronic diseases often receive multiple medications and are associated with increased vulnerability to medication errors. Identifying high-alert medications for them would help to prioritize the interventions with greatest impact for improving medication safety. The aim of this study was to develop a list of high-alert medications for patients with chronic illnesses (HAMC list) that would prove useful to the Spanish National Health Service strategies on chronicity.

METHODS

The RAND/UCLA appropriateness method was used. Drug classes/drugs candidates to be included on the HAMC list were identified from a literature search in MedLine, bulletins issued by patient safety organizations, incidents recorded in Spanish incident reporting systems, and previous lists. Eighteen experts in patient/medication safety or in chronic diseases scored candidate drugs for appropriateness according to three criteria (evidence, benefit and feasibility of implementing safety practices). Additionally they rated their priority of inclusion on a Likert scale.

RESULTS

The final HAMC list includes 14 drug classes (oral anticoagulants, narrow therapeutic range antiepileptics, antiplatelets - including aspirin -, antipsychotics, β-blockers, benzodiazepines and analogues, corticosteroids long-term use, oral cytostatics, oral hypoglycemic drugs, immunosuppressants, insulins, loop diuretics, nonsteroidal anti-inflammatory drugs, and opioid analgesics), and 4 drugs or pairs of drugs (amiodarone/ dronedarone, digoxin, oral methotrexate and spironolactone/eplerenone).

CONCLUSIONS

An initial list of high-alert medications for patients with chronic diseases has been developed, which can be built into the medication management strategies for chronicity to guide the implementation of efficient safety strategies and to identify those patients at greater risk for preventable adverse drug events.

Evaluation of dronedarone as a therapeutic option for patients with atrial fibrillation

WHAT IS KNOWN AND OBJECTIVE

Atrial fibrillation (AF) is the predominant dysrhythmia affecting approximately 2·4 million people in the United States and over 6 million Europeans. Dronedarone is a benzofuran derivative of amiodarone newly approved in 2009 for the treatment of AF. Here, we comment on the efficacy and safety of dronedarone in patients with AF.

COMMENT

Eight randomized controlled trials were analysed in this article. Several trials showed that dronedarone therapy delayed AF recurrence, controlled ventricular rate and reduced incidences of hospitalization or death. However, some of the studies were terminated early due to an excess mortality rate. Further studies on long-term safety and trials on direct comparison to rate controlling medications are suggested to obtain additional insight of dronedarone.

WHAT IS NEW AND CONCLUSION

Dronedarone reduces the incidence of AF recurrences, hospitalization and death in patients with paroxysmal or persistent AF. However, dronedarone should not be used in high-risk patients with permanent AF or patients with unstable chronic heart failure (HF) due to safety concerns.

Editorial: advances in the therapy of atrial fibrillation: incrementally progressive but not without missteps

Advances in the therapy of atrial fibrillation (AF) have not come easily or quickly, despite the recognized need for significantly better antiarrhythmic agents for AF termination and prevention as well as for more user-friendly anticoagulants for the prevention of emboli in patients with AF. Rather, the road has been only slowly progressive and bumpy. This manuscript will introduce the recent issues with dronedarone, the complex development story for vernakalant, and the appearance of the new oral anticoagulants. Each of these three considerations will then be explored in more depth by the invited experts for this "mini-Thematic issue" in Current Cardiology Reviews.

The role of dronedarone in the treatment of atrial fibrillation/flutter in the aftermath of PALLAS

Dronedarone is an amiodarone analog that differs structurally from amiodarone in that the iodine moiety was removed and a methane-sulfonyl group was added. These modifications reduce thyroid and other end-organ adverse effects and makes dronedarone less lipophilic, with a shorter half-life. Dronedarone has been shown to prevent atrial fibrillation/ flutter (AF/AFl) recurrences in several multi-center trials. In addition to its rhythm control properties, dronedarone has rate control properties. In patients with decompensated heart failure, dronedarone treatment increased mortality and cardiovascular hospitalizations. When dronedarone was used in elderly high risk AF/AFl patients, excluding those with advanced heart failure, cardiovascular hospitalizations were significantly reduced. The results of the PALLAS trial suggest that dronedarone should not be used in the long-term treatment of patients with permanent AF. Post-marketing data have demonstrated rare hepatic toxicity to be associated with dronedarone use. Updated practice and regulatory guidelines have positioned dronedarone as a front-line antiarrhythmic in many patients with AF/Fl. However, the drug should not be used in patients with advanced heart failure and in patients who develop permanent AF.

[New developments in the antiarrhythmic therapy of atrial fibrillation]

Atrial fibrillation often affects elderly people with cardiovascular disease and takes a progressive course with increasing resistance to treatment. For the latter, electrical and structural changes (remodelling) seem to be responsible that are directly related to the high excitatory rate in the atria. Therapeutic strategies for atrial fibrillation consist of (i) treating the underlying cardiovascular disease, (ii) re-establishing sinus rhythm and (iii) reducing ventricular rate. Rapid pharmacological or electrical cardioversion is expected to prevent remodelling. Classical antiarrhythmic drugs are notoriously ineffective and burdened with serious cardiac and extracardiac side effects so that there is an urgent need for effective and safe novel compounds. In this review the three recently introduced drugs dronedarone, vernakalant and ranolazine are discussed with respect to the use in atrial fibrillation. Other new antiarrhythmic agents are still in the developmental phase and aim at atria-selective mechanisms thereby excluding ventricular proarrhythmic effects. The mechanisms of action will be discussed in the context of the present understanding of the pathophysiology of onset and maintenance of atrial fibrillation.

Impact of dronedarone treatment on healthcare resource utilization in patients with atrial fibrillation/flutter

BACKGROUND

The ATHENA (A Placebo-Controlled, Double-Blind, Parallel Arm Trial to Assess the Efficacy of Dronedarone 400 mg bid for the Prevention of Cardiovascular Hospitalization or Death from Any Cause in Patients with Atrial Fibrillation/Atrial Flutter) trial demonstrated a significant reduction (26%) in the rate of first cardiovascular (CV) hospitalization in dronedarone-treated patients with paroxysmal or persistent atrial fibrillation/flutter (AF/AFL). ATHENA was the first trial to demonstrate a CV outcomes benefit, specifically reduced CV hospitalizations, with an antiarrhythmic drug. The objective of this study was to assess the impact of dronedarone treatment on healthcare resource utilization among real-world patients with AF/AFL in United States clinical practice.

METHODS

This retrospective cohort study used claims data from the MarketScan® databases (Truven Health, Durham, NC, USA) to identify patients with ≥2 concurrent de novo pharmacy claims for dronedarone (≥180 days' total supply) between June 2009 and March 2011, and with an AF/AFL diagnosis and no heart failure-related hospitalization during the 12 months preceding the initial (index) dronedarone claim. Annualized inpatient and outpatient resource utilization were compared between the pre-index (baseline) and post-index (follow-up) periods.

RESULTS

In total, 5,656 AF/AFL patients were prescribed dronedarone for ≥6 months and were followed for mean (standard deviation) 11.9 (4.7) months. Reductions in mean numbers of annualized all-cause, CV- and AF-related hospitalizations (~40-45%), and emergency department visits (~30-45%) were realized. These benefits were offset by increases in office visits (~10-30%) and AF-related prescription claims (74%) after dronedarone initiation. The sub-cohort of patients switching to dronedarone from Prior Rhythm-Control therapy (n=2,080) showed similar reductions in hospital and emergency department events.

CONCLUSIONS

This study suggests that dronedarone use in real-world practice, as in the ATHENA trial, results in substantial reductions in hospital admissions, both in first-line and second-line antiarrhythmic treatment settings.

Metabolite identification studies on amiodarone in in vitro (rat liver microsomes, rat and human liver S9 fractions) and in vivo (rat feces, urine, plasma) matrices by using liquid chromatography with high-resolution mass spectrometry and multiple-stage mass spectrometry: characterization of the diquinone metabolite supposedly responsible for the drug's hepatotoxicity

RATIONALE

Several mechanisms have been anticipated for the toxicity of amiodarone, such as oxidative stress, lipid peroxidation, phospholipidosis, free radical generation, etc. Amiodarone is structurally similar to benzbromarone, an uricosuric agent, which was withdrawn from European markets due to its idiosyncratic hepatotoxicity. A proposed reason behind the toxicity of benzbromarone was the production of a reactive ortho-diquinone metabolite, which was found to form adducts with glutathione. Therefore, taking a clue that a similar diquinone metabolite of amiodarone may be the reason for its hepatotoxicity, metabolite identification studies were carried out on the drug using liquid chromatography/mass spectrometry (LC/MS) tools.

METHODS

The studies involved in vitro (rat liver microsomes, rat liver S9 fraction, human liver S9 fraction) and in vivo (rat feces, urine, plasma) models, wherein the samples were analyzed by employing LC/HRMS, LC/MS(n) and HDE-MS.

RESULTS AND CONCLUSIONS

A total of 26 metabolites of amiodarone were detected in the investigated in vitro and in vivo matrices. The suspected ortho-diquinone metabolite was one of them. The formation of the same might be an added reason for the hepatotoxicity shown by the drug.

[Every sixth patient in amiodarone treatment develops thyrotoxicosis or hypothyreosis]

Amiodarone is associated with multiple side effects among which a substantial number of patients are suffering from amiodarone-induced thyroid disease. In this review we present difficulties in diagnosing, sub typing and treating amiodarone-induced thyroid disease and give views on the future of this drug and one of the alternatives, dronedarone. Amiodarone holds a place in modern medicine due to its unique antiarrhythmic effects and associated thyroid diseases requires collaboration between cardiologists and endocrinologists due to the complexity hereof.

[Appropriateness criteria for the treatment of atrial fibrillation with dronedarone: practical issues. An Italian cardiologists' expert opinion]

Antiarrhythmic agents are among the therapeutic options available for the treatment of atrial fibrillation when a rhythm control strategy is required. Although their efficacy seems to be generally comparable to that of nonpharmacological interventions, the use of these agents remains controversial. In particular, among this class of drugs, the use of dronedarone in clinical practice is a matter of debate. In this paper, the authors aimed to address these issues, involving a team of expert cardiologists who discussed about the potential use of dronedarone in different clinical scenarios. The RAND/UCLA appropriateness method was used to develop appropriateness measures for the optimal management of patients treated with dronedarone, by combining the best available scientific evidence with the collective judgment of experts. To this purpose, a group of experts was identified and asked to rate the benefit-to-harm ratio of 52 clinical scenarios. Each indication was classified as "appropriate", "uncertain" or "inappropriate" in accordance with the panelists' median score. The classification of each scenario has led to the development of several recommendations for clinical practice. The use of dronedarone for the management of paroxysmal and persistent atrial fibrillation has evolved over time: this antiarrhythmic drug appears to be useful not only in monitoring symptoms, but also in reducing hospitalization and mortality rates in patients with atrial fibrillation.

Dronaderone-induced phototoxicity

Phototoxicity is a skin reaction that occurs in patients using photosensitizing drugs in combination with exposure to ultraviolet light. Common photosensitizing pharmacologic agents include antibiotics, non-steroidal anti-inflammatory drugs, diuretics, neuroleptics, retinoids, and amiodarone. Dronaderone is a novel antiarrhythmic that is similar in composition to amiodarone, but is non-iodinated and also has a methane-sulfonyl group, significantly decreasing its incidence of adverse effects as compared to amiodarone. While phototoxicity is a commonly reported complication of amiodarone, this reaction has rarely been documented in patients using dronaderone. We report the case of a 63 year-old woman with a history of atrial fibrillation that presented with a phototoxic drug eruption following use of dronaderone for maintenance of normal sinus rhythm.

Amiodarone inhibits apamin-sensitive potassium currents

BACKGROUND

Apamin sensitive potassium current (I KAS), carried by the type 2 small conductance Ca(2+)-activated potassium (SK2) channels, plays an important role in post-shock action potential duration (APD) shortening and recurrent spontaneous ventricular fibrillation (VF) in failing ventricles.

OBJECTIVE

To test the hypothesis that amiodarone inhibits I KAS in human embryonic kidney 293 (HEK-293) cells.

METHODS

We used the patch-clamp technique to study I KAS in HEK-293 cells transiently expressing human SK2 before and after amiodarone administration.

RESULTS

Amiodarone inhibited IKAS in a dose-dependent manner (IC50, 2.67 ± 0.25 µM with 1 µM intrapipette Ca(2+)). Maximal inhibition was observed with 50 µM amiodarone which inhibited 85.6 ± 3.1% of IKAS induced with 1 µM intrapipette Ca(2+) (n = 3). IKAS inhibition by amiodarone was not voltage-dependent, but was Ca(2+)-dependent: 30 µM amiodarone inhibited 81.5±1.9% of I KAS induced with 1 µM Ca(2+) (n = 4), and 16.4±4.9% with 250 nM Ca(2+) (n = 5). Desethylamiodarone, a major metabolite of amiodarone, also exerts voltage-independent but Ca(2+) dependent inhibition of I KAS.

CONCLUSION

Both amiodarone and desethylamiodarone inhibit I KAS at therapeutic concentrations. The inhibition is independent of time and voltage, but is dependent on the intracellular Ca(2+) concentration. SK2 current inhibition may in part underlie amiodarone's effects in preventing electrical storm in failing ventricles.

Cost-effectiveness analysis of dronedarone versus other anti-arrhythmic drugs for the treatment of atrial fibrillation--results for Canada, Italy, Sweden and Switzerland

The ATHENA clinical trial enrolled 4,628 patients in 37 countries and evaluated the efficacy of dronedarone 400 mg twice daily versus placebo for the prevention of cardiovascular hospitalisation or death from any cause in patients with paroxysmal or persistent atrial fibrillation or atrial flutter. The trial showed a statistically significant 24% reduction in the primary endpoint cardiovascular hospitalisations or all-cause death. In the current paper, parameters that drive the cost-effectiveness of dronedarone on top of standard therapy versus likely comparators, i.e. amiodarone, sotalol and flecainide, were investigated by means of a health economic model based on the ATHENA clinical trial. Dronedarone is cost-effective, and ICERs are low versus amiodarone with €5,340; €4,620; €3,850 and €5,630 per QALY gained for Canada, Italy, Sweden and Switzerland, respectively. The most significant driving factor for the cost-effectiveness of dronedarone is the increased survival rate for patients on dronedarone.

Usefulness of dronedarone in patients with atrial arrhythmias

Dronedarone is a novel class III antiarrhythmic drug with moderate efficacy in preventing atrial arrhythmias. However, only few data from the real-world use of dronedarone with limited electrocardiographic monitoring are available. The investigators report the incidence, timing, and reasons for discontinuation of dronedarone; maintenance of sinus rhythm; and atrial arrhythmia recurrence patterns in 120 consecutive patients with atrial fibrillation (AF; n = 91) or non-isthmus-dependent atrial flutter (n = 29) treated with dronedarone (400 mg twice daily). Rhythm control was assessed with serial 7-day Holter electrocardiography after 4 weeks and after 6 to 9 months. After drug initiation, dronedarone was discontinued in 19 patients (16%) because of inefficacy (n = 7 [6%]) or adverse events (n = 12 [10%]). At 4 weeks, 44 patients (37%) had stopped taking dronedarone because of inefficacy (n = 27 [23%]) or adverse events (n = 17 [14%]). After 6 to 9 months, 25 patients (21%) had discontinued dronedarone because of clinical inefficacy (n = 16 [13%]) or adverse events (n = 9 [8%]). Overall, dronedarone was still used after 6 to 9 months in 32 patients (27%). Maintenance of sinus rhythm was achieved in 40 patients (33%) after 4 weeks and in 24 patients (20%) after 6 to 9 months. Reversal from persistent to paroxysmal arrhythmias was observed in 23 patients, (29%) whereas progression from paroxysmal to persistent arrhythmias occurred in 6 patients (15%). Conversion from AF to non-isthmus-dependent atrial flutter was noted in 10 patients (13%). In conclusion, dronedarone is associated with frequent adverse events and moderate antiarrhythmic efficacy requiring discontinuation in most patients within the first 9 months of use, and there is a prevalent reversal from persistent to paroxysmal but also from paroxysmal to persistent atrial arrhythmias and from AF to non-isthmus-dependent atrial flutter.

A Pharmacokinetic Study of the Combined Administration of Amiodarone and Ximelagatran, an Oral Direct Thrombin Inhibitor

The oral direct thrombin inhibitor ximelagatran is being developed for the prevention and treatment of thromboembolism. This single-blind, randomized, placebo-controlled, parallel-group study investigated the potential for the interaction of ximelagatran (36 mg every 12 hours for 8 days, measured as its active form melagatran in blood) and amiodarone (single 600-mg oral dose on day 4) in healthy male subjects (n = 26). For amiodarone + ximelagatran versus amiodarone + placebo, geometric mean ratios (90% confidence intervals for amiodarone AUC(0-120) and C(max) were 0.87 (0.69-1.08) and 0.86 (0.66-1.11), respectively. For desethylamiodarone, the principal metabolite of amiodarone, the corresponding ratios were 1.00 (0.89-1.12) for AUC(0-120) and 0.92 (0.77-1.09) for C(max). The geometric mean ratios (90% confidence intervals) for ximelagatran + amiodarone versus ximelagatran were 1.21 (1.17-1.25) for melagatran AUC(0-12) and 1.23 (1.18-1.28) for melagatran C(max). These confidence intervals were within or only slightly outside the interval, suggesting no interaction (0.8-1.25 for the effect of amiodarone on melagatran and 0.7-1.43 for the effect of melagatran on amiodarone or desethylamiodarone). Amiodarone did not affect the concentration-effect relationship of melagatran on activated partial thromboplastin time. Ximelagatran was well tolerated when coadministered with a single dose of amiodarone. Evaluation of the safety of the combination is needed to confirm that the relatively small pharmacokinetic changes in this study are of no clinical significance.

Ventricular tachycardia in "end stage" hypertrophic cardiomyopathy: a role of dronedarone

Hypertrophic cardiomyopathy (HCM) occurs in 1 in every 500 individuals. It represents the most common cause of sudden cardiac death in those under the age of twenty-five. 3-5% patients with HCM go on to develop the dilated, hypokinetic end stage (ES) HCM with systolic failure. They have a higher incidence of heart failure, sudden deaths and defibrillator shocks. To the best of our knowledge this is first report of successful use of dronedarone for suppression of VT associated with ES HCM.

[New antiarrhythmic drugs for the treatment of atrial fibrillation]

Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice and a difficult-to-treat arrhythmia. Conventional antiarrhythmic drugs, including flecainide, propafenone, sotalol and amiodarone, have several limitations in terms of efficacy and tolerability, and have made new drug development crucial. In the last decade, intensive research was undertaken to find new pharmacological options for the treatment of AF, and two new drugs are now available. Vernakalant is an atrial-selective drug specifically designed to block sodium channels at the atrial level, and its intravenous formulation has recently been recommended for approval by the Food and Drug Administration for pharmacological conversion of AF. Dronedarone is a chemical derivative of amiodarone (though having a significantly different clinical profile) with effects on multiple ion channels that proved effective in reducing the rate of the combined endpoint of death from any cause and cardiovascular hospitalization in patients with non-permanent AF enrolled in the ATHENA study. The available evidence on the efficacy of dronedarone has led to approval for recommendation in many clinical situations in which rhythm control is desirable. The complexity of the mechanisms underlying AF and the large variability of associated comorbidities render the AF patient a unique entity, making the identification of patients who may benefit from these novel approaches challenging.

Efficacy and safety profile of dronedarone in clinical practice. Results of the Magdeburg Dronedarone Registry (MADRE study)

BACKGROUND

Dronedarone is a new antiarrhythmic agent that has only recently been approved for the therapy of atrial fibrillation (AF). Results regarding a broader spectrum of patients and experience accumulated in clinical practice are still very scarce. Therefore, we prospectively investigated the efficacy and tolerance of dronedarone in a real life setting.

METHODS AND RESULTS

The study included 191 patients (85 women) aged 63 ± 9.9 years with a history of paroxysmal or persistent AF. Follow-up time was 14.3 ± 4.9 months. In patients with persistent AF, sinus rhythm was restored using electrical cardioversion prior to dronedarone administration. Each patient underwent standard ECG on a daily basis during the first 4 days of treatment, and on days 7, 30 and 90, resp. After that, the patients had a follow-up visit every three months. Creatinine, creatine kinase, and hepatic enzymes were closely monitored. Clinical history was meticulously taken at multiple follow-up visits. Dronedarone maintained sinus rhythm in 33.5% (95% CI: 27%-40%), and AF recurrence rate was high: 66.5% (95% CI: 60%-73%). Adverse effects occurred in 31.9% (95% CI: 27%-38%) of the patients and necessitated permanent discontinuation of dronedarone in 22% (95% CI: 17%-27%).

CONCLUSIONS

The results suggest that dronedarone may not be superior to available antiarrhythmic agents and caution against its use as a first line therapy in AF.

Pharmacology of myocardial calcium-handling

Disturbed myocardial calcium (Ca(+)) handling is one of the pathophysiologic hallmarks of cardiovascular diseases such as congestive heart failure, cardiac hypertrophy, and certain types of tachyarrhythmias. Pharmacologic treatment of these diseases thus focuses on restoring myocardial Ca(2+) homeostasis by interacting with Ca(2+)-dependent signaling pathways. In this article, we review the currently used pharmacologic agents that are able to restore or maintain myocardial Ca(2+) homeostasis and their mechanism of action as well as emerging new substances.

Dronedarone prevents microcirculatory abnormalities in the left ventricle during atrial tachypacing in pigs

BACKGROUND AND PURPOSE

Atrial fibrillation induces ischaemic microcirculatory flow abnormalities in the ventricle, contributing to the risk for acute coronary syndromes. We evaluated the effect of dronedarone on ventricular perfusion during rapid atrial pacing (RAP).

EXPERIMENTAL APPROACH

Coronary and fractional flow reserve (CFR/FFR) were measured in the left anterior descending artery in 29 pigs. Six received RAP, six received RAP with dronedarone (RAP/D), seven received dronedarone alone, four received RAP with amiodarone (RAP/A), and six received neither (sham). In ventricular tissue, oxidative stress/ischaemia-related gene and protein expression was evaluated by RT-PCR and Western blotting; Isoprostanes were measured by GC-MS procedures.

KEY RESULTS

CFR was decreased in the RAP group, compared with other groups. FFR was not different between groups. Effective refractory period was reduced in RAP compared with RAP/D. RAP-activated PKC phosphorylation tended to be decreased by dronedarone (P= 0.055) RAP induced NOX-1 and NOX-2 protein and the mRNA for hypoxia-inducible factor-1α (HIF-1α). Dronedarone reduced the pacing-dependent increase in the expression of NOX-2 protein and of HIF-1α mRNA. The oxidative stress marker, F(2)-isoprostane, was increased by RAP and this increase was attenuated by dronedarone. Other oxidative stress/ischaemia-related genes were induced by RAP compared with sham and were decreased by dronedarone treatment. In HL1 cells, dronedarone significantly inhibited the increased phosphorylation of PKCα after oxidative stress, with an almost significant effect (P= 0.059) on that after RAP.

CONCLUSIONS AND IMPLICATIONS

Dronedarone abolished RAP-induced ventricular microcirculatory abnormalities by decreasing oxidative stress/ischaemia-related gene and protein expression in the ventricle.

Dronedarone for the treatment of atrial fibrillation: a NICE single technology appraisal

The National Institute for Health and Clinical Excellence (NICE) invited the manufacturer of dronedarone (Multaq®, Sanofi-Aventis Limited, UK) to submit evidence on the clinical and cost effectiveness of the anti-arrhythmic drug (AAD) for the treatment of atrial fibrillation (AF) and atrial flutter, as part of the Institute's single technology appraisal (STA) process. The Centre for Reviews and Dissemination and the Centre for Health Economics, both at the University of York, were commissioned to act as the independent Evidence Review Group (ERG). This article provides a description of the company submission, the ERG review and NICE's subsequent decisions regarding the use of dronedarone within the UK NHS. The ERG review comprised a critique of the submitted evidence on the clinical effectiveness and cost effectiveness of dronedarone. The ERG examined the search strategy used to obtain relevant evidence, the selection of studies included in the assessment, outcome measures chosen and statistical methods employed. The ERG also validated the manufacturer's decision analytic model and used it to explore the robustness of the cost-effectiveness results to key assumptions. The main clinical effectiveness evidence supporting the use of dronedarone as a treatment for AF came from four randomized controlled trials. These trials were compared with a broader set of trials examining the effectiveness of other AADs for AF: amiodarone, sotalol and class 1c agents (flecainide and propafenone). The evidence suggested that all AADs decreased the recurrence of AF but dronedarone had the smallest effect. A mixed treatment comparison analysis of the trials showed that dronedarone was associated with a lower risk of all-cause mortality than other AADs, but this was highly uncertain. There was limited evidence to assess the effect of dronedarone on stroke, and no statistically significant differences between dronedarone and other AADs were found for treatment discontinuation. From the evidence presented by the manufacturer, dronedarone appeared highly cost effective in each of the population groups examined compared with using standard baseline therapy alone as first-line treatment, or compared with sotalol or amiodarone as first-line AAD, with incremental cost-effectiveness ratios (ICERs) well below £20,000 per QALY gained. The ICER for dronedarone relative to class 1c agents was around £19,000 per QALY. Although the evidence presented by the manufacturer indicated that dronedarone was cost effective, the estimates of treatment effect relative to other AADs and safety in the longer term were highly uncertain. The NICE Appraisal Committee in its preliminary guidance did not recommend the use of dronedarone for AF. However, following the response from a large number of consultees and commentators, NICE revised its preliminary guidance to allow the use of the drug in a specific subgroup of AF patients with additional cardiovascular risk factors.

Käypä hoito -suosituksen päivitystiivistelmä. [Update on current care guidelines: atrial fibrillation]

According to the update of the Finnish guidelines for management of patients with atrial fibrillation (AF) dronedarone should be used only in patients with non-permanent AF as a second line medication. It is recommended to monitor the patients regularly and stop dronedarone if permanent AF, heart failure or other adverse events are detected. Dabigatran and rivaroxaban can be used as an alternative to warfarin in patients requiring oral anticoagulation therapy. The selection between warfarin and the new anticoagulants should be based on careful evaluation of the benefits and disadvantages of the drugs in a given patient.

[Amiodarone and thyroid dysfunction]

Amiodarone is a structural analogue of thyroid hormone, and some of its anti-arrhythmic actions and toxicity are attributable to its interaction with nuclear receptors of thyroid hormones. Being highly lipophilic, amiodarone is concentrated in many tissues and is eliminated, consequently, very slowly. It is preferably employed to manage life-threatening arrhythmias, including ventricular fibrillation and unstable ventricular tachycardia. Other indications include atrial fibrillation and flutter, severe congestive heart failure, prevention of atrial fibrillation recurrence, and even in emergency medical situations to prevent sudden cardiac death. The aim of this review is to provide an updated approach on amiodarone and its influence on thyroid physiology and to discuss and analyze in depth its potential and not infrequent thyroidal adverse effects such as hypothyroidism and thyrotoxicosis.

[Effect of amiodarone on the thyroid function and safety of the therapy--what's new]

This paper presents the current state of knowledge on the effects of amiodarone (AM) on the thyroid gland function, including the question of epidemiology, pathogenesis and prognostic factors. Of all the antiarrhythmic drugs hitherto used, AM has the most adverse effects on the thyroid gland. In patients receiving AM, it may lead to a development of a full- symptomatic hyperthyroidism (AIT-Amiodarone-induced thyrotoxicosis) and hypothyroidism (AIH - Amiodarone-induced hypothyroidism). The time from the start of the treatment of AM to the onset of symptoms of thyrotoxicosis is varied and amounts approximately to 3 years. The AIT may develop up to 2 years after the cessation of the AM treatment because of the accumulation of the drug and its metabolites in the body. The AIT treatment is complicated and often requires multiple treatment methods, such as: antithyroid drugs, glucocorticoids, iopanic acid, plasmapheresis, thyroidectomy and radioiodine. AIH is associated with the Wolff-Chaikoffa phenomenon. Thyroid hormone synthesis is impaired by blocking iodine organification. Hypothyroidism can also arise and be exacerbated by the output of thyroid disease - autoimmune diseases. The paper also devotes much attention to the relationship between smoking and the toxicity of AM. The components of tobacco smoke increase the activity of enzymes involved in the metabolism of AM. Increased concentrations of desetyloamiodarone in lung tissue may be responsible for the increased toxicity in the lungs in smokers. In addition, the paper presents a new antiarrhythmic drug - dronedarone (DN), an attractive alternative, but, because of the high risk of heart failure, stroke and death from cardiovascular disease, with a limited potential.

Mitochondrial oxidative stress and respiratory chain dysfunction account for liver toxicity during amiodarone but not dronedarone administration

The role played by oxidative stress in amiodarone-induced mitochondrial toxicity is debated. Dronedarone shows pharmacological properties similar to those of amiodarone but several differences in terms of toxicity. In this study, we analyzed the effects of the two drugs on liver mitochondrial function by administering an equivalent human dose to a rat model. Amiodarone increased mitochondrial H(2)O(2) synthesis, which in turn induced cardiolipin peroxidation. Moreover, amiodarone inhibited Complex I activity and uncoupled oxidative phosphorylation, leading to a reduction in the hepatic ATP content. We also observed a modification of membrane phospholipid composition after amiodarone administration. N-acetylcysteine completely prevented such effects. Although dronedarone shares with amiodarone the capacity to induce uncoupling of oxidative phosphorylation, it did not show any of the oxidative effects and did not impair mitochondrial bioenergetics. Our data provide important insights into the mechanism of mitochondrial toxicity induced by amiodarone. These results may greatly influence the clinical application and toxicity management of these two antiarrhythmic drugs.

Dronedarone in high-risk permanent atrial fibrillation

BACKGROUND

Dronedarone restores sinus rhythm and reduces hospitalization or death in intermittent atrial fibrillation. It also lowers heart rate and blood pressure and has antiadrenergic and potential ventricular antiarrhythmic effects. We hypothesized that dronedarone would reduce major vascular events in high-risk permanent atrial fibrillation.

METHODS

We assigned patients who were at least 65 years of age with at least a 6-month history of permanent atrial fibrillation and risk factors for major vascular events to receive dronedarone or placebo. The first coprimary outcome was stroke, myocardial infarction, systemic embolism, or death from cardiovascular causes. The second coprimary outcome was unplanned hospitalization for a cardiovascular cause or death.

RESULTS

After the enrollment of 3236 patients, the study was stopped for safety reasons. The first coprimary outcome occurred in 43 patients receiving dronedarone and 19 receiving placebo (hazard ratio, 2.29; 95% confidence interval [CI], 1.34 to 3.94; P=0.002). There were 21 deaths from cardiovascular causes in the dronedarone group and 10 in the placebo group (hazard ratio, 2.11; 95% CI, 1.00 to 4.49; P=0.046), including death from arrhythmia in 13 patients and 4 patients, respectively (hazard ratio, 3.26; 95% CI, 1.06 to 10.00; P=0.03). Stroke occurred in 23 patients in the dronedarone group and 10 in the placebo group (hazard ratio, 2.32; 95% CI, 1.11 to 4.88; P=0.02). Hospitalization for heart failure occurred in 43 patients in the dronedarone group and 24 in the placebo group (hazard ratio, 1.81; 95% CI, 1.10 to 2.99; P=0.02).

CONCLUSIONS

Dronedarone increased rates of heart failure, stroke, and death from cardiovascular causes in patients with permanent atrial fibrillation who were at risk for major vascular events. Our data show that this drug should not be used in such patients. (Funded by Sanofi-Aventis; PALLAS ClinicalTrials.gov number, NCT01151137.).

Safety of dronedarone (Multaq)

Dronedarone (Multaq-Sanofi), an analog of amiodarone, was approved by the FDA in 2009 for oral treatment of paroxysmal or persistent (non-permanent) atrial fibrillation or atrial flutter. Amiodarone (Cordarone, and others) is more effective for this indication, but its use is often limited by its adverse effects, including thyroid and pulmonary toxicity.