Structure-Activity Relationship and Voltage Dependence for the Drug-Drug Interaction between Amiodarone Analogs and MNI-1 at the L-type Cav Channel.

The drug-drug interaction (DDI) between amiodarone (AMIO) and sofosbuvir (SOF), a direct-acting hepatitis-C NS5B nucleotide polymerase inhibitor, has been associated with severe bradyarrhythmia in patients. Recent cryo-EM data has revealed that this DDI occurs at the α-subunit of L-type Cav channels, with AMIO binding at the fenestration site and SOF [or MSD nucleotide inhibitor #1 (MNI-1): analog of SOF] binding at the central cavity of the conductance pathway. In this study, we investigated the DDI between 21 AMIO analogs, including dronedarone (DRON) and MNI-1 (or SOF) in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and hCav1.2 models. Our findings indicate that among the tested AMIO analogs in hiPSC-CMs at clinically relevant concentrations, only three analogs (AA-9, AA-10, and AA-17) were able to effectively substitute for AMIO in this DDI with 1 µM MNI-1. This highlights the importance of the diethyl amino group of AMIO for interacting with MNI-1. In the hCav1.2 model, desethylamiodarone (AA-12) demonstrated synergy with 90 µM MNI-1, while three other analogs with modifications to the position of the diethyl amino group or removal of iodo groups showed weaker synergy with 90 µM MNI-1. Interestingly, DRON did not exhibit any interaction with 270 µM SOF or 90 µM MNI-1, suggesting that it could safely replace AMIO in patients requiring SOF treatment, other clinically relevant differences considered. Overall, our functional data align with the cryo-EM data, highlighting that this DDI is dependent on the structure of AMIO and cardiomyocyte resting membrane potential. SIGNIFICANCE STATEMENT: Our findings point to specific residues in the AMIO molecule playing a critical role in the DDI between AMIO and MNI-1 (SOF analog), confirming cryo-EM results. Applied at clinically relevant AMIO's concentrations or projected MNI-1's concentrations at the resting potentials mimicking the sinoatrial node, this DDI significantly slowed down or completely inhibited the beating of hiPSC-CMs. Finally, these in vitro results support the safe replacement of AMIO (Cordarone) with DRON (Multaq) for patients requiring SOF treatment, other clinical caveats considered.

Amiodarone inhibits the Toll-like receptor 3-mediated nuclear factor κB signaling pathway by blocking organelle acidification.

Toll-like receptor (TLR) agonists or pro-inflammatory cytokines converge to activate the nuclear factor κB (NF-κB) signaling pathway, which provokes inflammatory responses. In the present study, we identified amiodarone hydrochloride as a selective inhibitor of the TLR3-mediated NF-κB signaling pathway by screening the RIKEN NPDepo Chemical Library. In human umbilical vein endothelial cells (HUVEC), amiodarone selectively inhibited the expression of intercellular adhesion molecule-1 (ICAM-1) induced by polyinosinic-polycytidylic acid (Poly(I:C)), but not tumor necrosis factor-α, interleukin-1α, or lipopolysaccharide. In response to a Poly(I:C) stimulation, amiodarone at 20 µM reduced the up-regulation of mRNA expression encoding ICAM-1, vascular cell adhesion molecule-1, and E-selectin. The nuclear translocation of the NF-κB subunit RelA was inhibited by amiodarone at 15-20 µM in Poly(I:C)-stimulated HUVEC. Amiodarone diminished the fluorescent dots of LysoTracker® Red DND-99 scattered over the cytoplasm of HUVEC. Therefore, the present study revealed that amiodarone selectively inhibited the TLR3-mediated NF-κB signaling pathway by blocking the acidification of intracellular organelles.

Microfluidic production of amiodarone loaded nanoparticles and application in drug repositioning in ovarian cancer.

Amiodarone repositioning in cancer treatment is promising, however toxicity limits seem to arise, constraining its exploitability. Notably, amiodarone has been investigated for the treatment of ovarian cancer, a tumour known for metastasizing within the peritoneal cavity. This is associated with an increase of fatty acid oxidation, which strongly depends on CPT1A, a transport protein which has been found overexpressed in ovarian cancer. Amiodarone is an inhibitor of CPT1A but its role still has to be explored. Therefore, in the present study, amiodarone was tested on ovarian cancer cell lines with a focus on lipid alteration, confirming its activity. Moreover, considering that drug delivery systems could lower drug side effects, microfluidics was employed for the development of drug delivery systems of amiodarone obtaining simultaneously liposomes with a high payload and amiodarone particles. Prior to amiodarone loading, microfluidics production was optimized in term of temperature and flow rate ratio. Moreover, stability over time of particles was evaluated. In vitro tests confirmed the efficacy of the drug delivery systems.

State-independent inhibition of the oncogenic Kv10.1 channel by desethylamiodarone, a comparison with amiodarone.

Kv10.1 is a voltage-dependent K channel whose ectopic expression is associated with several human cancers. Additionally, Kv10.1 has structure-function properties which are not yet well understood. We are using drugs of clinical importance in an attempt to gain insight on the relationship between pharmacology and characteristic functional properties of this channel. Herein, we report the interaction of desethylamiodarone (desAd), the active metabolic product of the antiarrhythmic amiodarone with Kv10.1: desAd binds to both closed and open channels, with most inhibition taking place from the open state, with affinity ~ 5 times smaller than that of amiodarone. Current inhibition by desAd and amiodarone is not synergistic. Upon repolarization desAd becomes trapped in Kv10.1 and thereafter dissociates slowly from closed-and-blocked channels. The addition of the Cole-Moore shift plus desAd open-pore-block time courses yields an increasing phase on the steady-state inhibition curve (H∞) at hyperpolarized holding potentials. In contrast to amiodarone, desAd does not inhibit the Kv10.1 Cole-Moore shift, suggesting that a relevant hydrophobic interaction between amiodarone and Kv10.1 participates in the inhibition of the Cole-Moore shift, which is lost with desAd.

Influence of quercetin on amiodarone pharmacokinetics and biodistribution in rats.

OBJECTIVE: Amiodarone (AMD), a drug of choice to treat cardiac arrhythmias, has a narrow therapeutic index (NTI). It inhibits CYP3A4, CYP2C9, and CYP2D6 enzymes. Quercetin (QUE), a pharmacologically important bioflavonoid in vegetables and fruits, is important in treating cardiovascular comorbidities. QUE alters the bioavailability of drugs used concurrently by dual inhibition of P-glycoproteins (P-gp) and cytochrome (CYP) enzyme systems. The current study aimed to investigate the pre-treatment and co-administration effect of QUE on AMD pharmacokinetics in rats. MATERIALS AND METHODS: Two separate animal trials (I and II) were planned to probe the effect of QUE on AMD pharmacokinetics by following previously cited studies. The pre-treatment group received oral doses of QUE for 14 days, and a single dose of AMD on the 15th day. Rats were administered single doses of QUE (20 mg/kg) and AMD (50 mg/kg) concurrently in a carboxymethylcellulose (CMC) in the co-administration study. Blood was collected at pre-determined time points. AMD was quantified by HPLC, and data was analyzed by PK solver software. RESULTS: In the pre-treated group, peak plasma concentration (Cmax) and area under the curve (AUC0-∞) of AMD were increased by 45.52% and 13.70%, respectively, while time to achieve maximum concentration (tmax), half-life (t1/2) and clearance (CL) were declined by 35.72%, 16.75%, and 11.0% respectively compared to the control. In the co-administered group, compared to controls, Cmax and AUC0-∞ were elevated to 12.90% and 7.80%, respectively, while tmax, t1/2, and CL declined by 16.70%, 2.35%, and 13.40%. Further, AMD was increased in lung tissue of both treated groups, relative to the respective controls. CONCLUSIONS: A notable pharmacokinetic drug interaction between QUE and AMD was observed in rats and warrants possible drug interaction study in humans, suggesting AMD dose adjustment specifically in patients with arrhythmia having a pre-treatment history and simultaneous administration of QUE-containing products.

Interaction of the antiarrhythmic drug Amiodarone with the sodium channel Nav1.5 depends on the extracellular pH.

INTRODUCTION: Amiodarone (AMD) is a clinically used drug to treat arrhythmias with significant effect upon the cardiac sodium channel Nav1.5. AMD has a pKa of 6.56, and changes in extracellular pH (pHe) may alter its pharmacological properties. Here we explored how changes in pHe impacts the pharmacological properties of AMD upon human-Nav1.5-sodium-current (INa) and in ex vivo rat hearts. METHODS: Embryonic-human-kidney-cells (HEK293) were used to transiently express the human alpha-subunit of NaV1.5 channels and the isolated heart of Wistar rats were used. Patch-Clamp technique was deployed to study INa and for electrocardiogram (ECG) evaluation the ex vivo heart preparation in the Langendorff system was applied. RESULTS: The potency of AMD upon peak INa was ∼25x higher in pHe 7.0 when compared to pHe 7.4. Voltage dependence for activation did not differ among all groups. AMD shifted the steady-state inactivation curve to more hyperpolarized potentials, with similar magnitudes for both pHes. The recovery from INa inactivation was delayed in the presence of AMD with similar profile in both pHes. Interestingly, the use-dependent properties of AMD was distinct at pHe 7.0 and 7.4. Finally, AMD was able to change the ex vivo ECG profile, however at pHe 7.0+AMD a larger increase in the RR and QRS duration and in the QT interval when compared to pHe 7.4 was found. CONCLUSIONS: The pharmacological properties of AMD upon NaV1.5 and isolated heart preparation depends on the pHe and its use in vivo during extracellular acidosis may cause a distinct biological response in the heart tissue.

Amiodarone prevents wave front-tail interactions in patients with heart failure: an in silico study.

Amiodarone (AM) is an antiarrhythmic drug whose chronic use has proved effective in preventing ventricular arrhythmias in a variety of patient populations, including those with heart failure (HF). AM has both class III [i.e., it prolongs the action potential duration (APD) via blocking potassium channels) and class I (i.e., it affects the rapid sodium channel) properties; however, the specific mechanism(s) by which it prevents reentry formation in patients with HF remains unknown. We tested the hypothesis that AM prevents reentry induction in HF during programmed electrical stimulation (PES) via its ability to induce postrepolarization refractoriness (PRR) via its class I effects on sodium channels. Here we extend our previous human action potential model to represent the effects of both HF and AM separately by calibrating to human tissue and clinical PES data, respectively. We then combine these models (HF + AM) to test our hypothesis. Results from simulations in cells and cables suggest that AM acts to increase PRR and decrease the elevation of takeoff potential. The ability of AM to prevent reentry was studied in silico in two-dimensional sheets in which a variety of APD gradients (ΔAPD) were imposed. Reentrant activity was induced in all HF simulations but was prevented in 23 of 24 HF + AM models. Eliminating the AM-induced slowing of the recovery of inactivation of the sodium channel restored the ability to induce reentry. In conclusion, in silico testing suggests that chronic AM treatment prevents reentry induction in patients with HF during PES via its class I effect to induce PRR.NEW & NOTEWORTHY This work presents a new model of the action potential of the human, which reproduces the complex dynamics during premature stimulation in heart failure patients with and without amiodarone. A specific mechanism of the ability of amiodarone to prevent reentrant arrhythmias is presented.

Exploring the inhibitory potential of the antiarrhythmic drug amiodarone against Clostridioides difficile toxins TcdA and TcdB.

The intestinal pathogen Clostridioides difficile is the leading cause of antibiotic-associated diarrhea and pseudomembranous colitis in humans. The symptoms of C. difficile-associated diseases (CDADs) are directly associated with the pathogen's toxins TcdA and TcdB, which enter host cells and inactivate Rho and/or Ras GTPases by glucosylation. Membrane cholesterol is crucial during the intoxication process of TcdA and TcdB, and likely involved during pore formation of both toxins in endosomal membranes, a key step after cellular uptake for the translocation of the glucosyltransferase domain of both toxins from endosomes into the host cell cytosol. The licensed drug amiodarone, a multichannel blocker commonly used in the treatment of cardiac dysrhythmias, is also capable of inhibiting endosomal acidification and, as shown recently, cholesterol biosynthesis. Thus, we were keen to investigate in vitro with cultured cells and human intestinal organoids, whether amiodarone preincubation protects from TcdA and/or TcdB intoxication. Amiodarone conferred protection against both toxins independently and in combination as well as against toxin variants from the clinically relevant, epidemic C. difficile strain NAP1/027. Further mechanistic studies suggested that amiodarone's mode-of-inhibition involves also interference with the translocation pore of both toxins. Our study opens the possibility of repurposing the licensed drug amiodarone as a novel pan-variant antitoxin therapeutic in the context of CDADs.

What determines the optimal pharmacological treatment of atrial fibrillation? Insights from in silico trials in 800 virtual atria.

The best pharmacological treatment for each atrial fibrillation (AF) patient is unclear. We aim to exploit AF simulations in 800 virtual atria to identify key patient characteristics that guide the optimal selection of anti-arrhythmic drugs. The virtual cohort considered variability in electrophysiology and low voltage areas (LVA) and was developed and validated against experimental and clinical data from ionic currents to ECG. AF sustained in 494 (62%) atria, with large inward rectifier K+ current (IK1 ) and Na+ /K+ pump (INaK ) densities (IK1 0.11 ± 0.03 vs. 0.07 ± 0.03 S mF-1 ; INaK 0.68 ± 0.15 vs. 0.38 ± 26 S mF-1 ; sustained vs. un-sustained AF). In severely remodelled left atrium, with LVA extensions of more than 40% in the posterior wall, higher IK1 (median density 0.12 ± 0.02 S mF-1 ) was required for AF maintenance, and rotors localized in healthy right atrium. For lower LVA extensions, rotors could also anchor to LVA, in atria presenting short refractoriness (median L-type Ca2+ current, ICaL , density 0.08 ± 0.03 S mF-1 ). This atrial refractoriness, modulated by ICaL and fast Na+ current (INa ), determined pharmacological treatment success for both small and large LVA. Vernakalant was effective in atria presenting long refractoriness (median ICaL density 0.13 ± 0.05 S mF-1 ). For short refractoriness, atria with high INa (median density 8.92 ± 2.59 S mF-1 ) responded more favourably to amiodarone than flecainide, and the opposite was found in atria with low INa (median density 5.33 ± 1.41 S mF-1 ). In silico drug trials in 800 human atria identify inward currents as critical for optimal stratification of AF patient to pharmacological treatment and, together with the left atrial LVA extension, for accurately phenotyping AF dynamics. KEY POINTS: Atrial fibrillation (AF) maintenance is facilitated by small L-type Ca2+ current (ICaL ) and large inward rectifier K+ current (IK1 ) and Na+ /K+ pump. In severely remodelled left atrium, with low voltage areas (LVA) covering more than 40% of the posterior wall, sustained AF requires higher IK1 and rotors localize in healthy right atrium. For lower LVA extensions, rotors can also anchor to LVA, if the atria present short refractoriness (low ICaL ) Vernakalant is effective in atria presenting long refractoriness (high ICaL ). For short refractoriness, atria with fast Na+ current (INa ) up-regulation respond more favourably to amiodarone than flecainide, and the opposite is found in atria with low INa . The inward currents (ICaL and INa ) are critical for optimal stratification of AF patient to pharmacological treatment and, together with the left atrial LVA extension, for accurately phenotyping AF dynamics.

Oxidative Brain Injury Induced by Amiodarone in Rats: Protective Effect of S-methyl Methionine Sulfonium Chloride.

Amiodarone (AMD) is a powerful antiarrhythmic drug preferred for treatments of tachycardias. Brain can be affected negatively when some drugs are used, including antiarrhythmics. S-methyl methionine sulfonium chloride (MMSC) is a well-known sulfur containing substance and a novel powerful antioxidant. It was intended to investigate the protective effects of MMSC on amiodarone induced brain damage. Rats were divided to four groups as follows, control (given corn oil), MMSC (50 mg/kg per day), AMD (100 mg/kg per day), AMD (100 mg/kg per day) + MMSC (50 mg/kg per day). The brain glutathione and total antioxidant levels, catalase, superoxide dismutase, glutathione peroxidase, paraoxonase, and Na+/K+-ATPase activities were decreased, lipid peroxidation and protein carbonyl, total oxidant status, oxidative stress index and reactive oxygen species levels, myeloperoxidase, acetylcholine esterase and lactate dehydrogenase activities were increased after AMD treatment. Administration of MMSC reversed these results. We can conclude that MMSC ameliorated AMD induced brain injury probably due to its antioxidant and cell protective effect.

Antiviral activity of amiodarone in SARS-CoV-2 disease.

Amiodarone seems to exhibit some antiviral activity in the disease caused by SARS-CoV-2. Here we have examined the SARS-CoV-2 disease course in the entire population of the Czech Republic and compared it with the course of the disease in patients treated with amiodarone in two major Prague's hospitals. In the whole population of the Czech Republic SARS-CoV-2 infected 1665070 persons (15.6 %) out of 10694000 (100 %) between 1 April 2020 and 30 June 2021. In the same time period only 35 patients (3.4 %) treated with amiodarone were infected with SARS-CoV-2 virus out of 1032 patients (100 %) who received amiodarone. It appears that amiodarone can prevent SARS-CoV-2 virus infection by multiple mechanisms. In in-vitro experiments it exhibits SARS-CoV-2 virus replication inhibitions. Due to its anti-inflammatory and antioxidant properties, it may have beneficial effect on the complications caused by SARS-CoV-2 as well. Additionally, inorganic iodine released from amiodarone can be converted to hypoiodite (IO-), which has antiviral and antibacterial activity, and thus can affect the life cycle of the virus.

Structural basis for the severe adverse interaction of sofosbuvir and amiodarone on L-type Cav channels.

Drug-drug interaction of the antiviral sofosbuvir and the antiarrhythmics amiodarone has been reported to cause fatal heartbeat slowing. Sofosbuvir and its analog, MNI-1, were reported to potentiate the inhibition of cardiomyocyte calcium handling by amiodarone, which functions as a multi-channel antagonist, and implicate its inhibitory effect on L-type Cav channels, but the molecular mechanism has remained unclear. Here we present systematic cryo-EM structural analysis of Cav1.1 and Cav1.3 treated with amiodarone or sofosbuvir alone, or sofosbuvir/MNI-1 combined with amiodarone. Whereas amiodarone alone occupies the dihydropyridine binding site, sofosbuvir is not found in the channel when applied on its own. In the presence of amiodarone, sofosbuvir/MNI-1 is anchored in the central cavity of the pore domain through specific interaction with amiodarone and directly obstructs the ion permeation path. Our study reveals the molecular basis for the physical, pharmacodynamic interaction of two drugs on the scaffold of Cav channels.

Amiodarone-drove XBP1s aggravates endoplasmic reticulum stress and apoptosis in Hashimoto's thyroiditis through regulating LINC00842/miR-214/FASL axis.

Hashimoto's thyroiditis (HT) is an organ-specific autoimmune disease, that eventually lead to hypothyroidism. XBP1s is an endoplasmic reticulum stress related protein and participates in the pathogenesis of several diseases. Nevertheless, the potential role of XBP1s in amiodarone (AMIO)-treated HT patients remains unknown. In this study, AMIO aggravated the endoplasmic reticulum stress responses in HT patients and thyroid epithelial follicular cells. Moreover, MTT assay and flow cytometry analysis revealed that knockdown of XBP1s suppressed AMIO-induced thyroid epithelial follicular cells apoptosis. Mechanically, the Chromatin Immunoprecipitation (ChIP) and luciferase activity assay proved that XBP1s enhanced LINC00842 expression in HT patients and thyroid epithelial follicular cells via binding to LINC00842 promoter. LINC00842 functioned as a miR-214 sponge in HT patients and thyroid epithelial follicular cells. Besides, LINC00842 up-regulated Fas ligand (FASL) expression via inhibition of miR-214. In rescue experiments, overexpression of FASL reversed shXBP1s-induced suppression of cell apoptosis in AMIO-treated thyroid epithelial follicular cells. These findings concluded that AMIO-drove XBP1s aggravated endoplasmic reticulum stress and apoptosis in HT via modulating LINC00842/miR-214/FASL axis, providing a new sight for the therapeutic strategy of AMIO-induced HT.

Interaction of Amiodarone with Azoles Against Aspergillus Planktonic Cells and Biofilms in vitro.

Aspergillus spp. is the most common clinical pathogen of invasive fungal infection with high mortality. Existing treatments for Aspergillus spp. infection are still inefficient and accompanied by drug resistance, so it is still urgent to find new treatment approaches. The antiarrhythmic drug amiodarone (AMD) has demonstrated antifungal activity against a range of fungi. This study evaluated the efficacy of AMD in combination with triazoles for Aspergillus spp. infection. We tested the combined effect of AMD and three triazole drugs, namely, itraconazole (ITR), voriconazole (VRC), and posaconazole (POS), on the planktonic cells and biofilms of 20 strains of Aspergillus spp. via a checkerboard microdilution assay derived from 96-well plate-based method. Our results reveal that the combination of AMD with ITR or POS against Aspergillus biofilms has synergistic fungicidal effects. By contrast, the combination of AMD with VRC exhibits no antagonistic and synergistic effects. In this way, the use of AMD in combination with ITR or POS could be an effective adjunctive treatment for Aspergillus spp. infection.

Amiodarone improves anemia in a murine model of sickle cell disease and is associated with increased erythrocyte bis(monoacylglycerol) phosphate.

Sickle cell disease (SCD) is associated with altered plasma and erythrocyte lipid profiles. In a previous study, SCD mice with deficiency of proprotein convertase subtilisin/kexin type 9 (PCSK9) were observed to have more severe anemia and increased sickling compared to control SCD mice. Although PCSK9 affects circulating low density lipoprotein (LDL) by regulation of the LDL receptor, the effect of PCSK9 on anemia was independent of LDL receptor expression. In the current study, erythrocyte metabolomics were performed and revealed altered erythrocyte lipid species between SCD mice with and without PCSK9. Of particular interest, the late endosome-specific lipid bis(mono)acylglycerol phosphate (BMP) 44:12 was markedly decreased in erythrocytes from SCD mice deficient in PCSK9 mice relative to control SCD mice. Incubation of sickle erythrocytes with a neutralizing antibody to BMP increased erythrocyte sickling in vitro. In vitro treatment of SCD erythrocytes with amiodarone (1.5 µM) or medroxyprogesterone (6.75 µM), two pharmacologic compounds known to increase BMP, resulted in reduced erythrocyte sickling. Treatment of SCD mice with amiodarone (10 mg/kg) for 2 weeks resulted in increased BMP, improvement in anemia with reduced reticulocytosis, and decreased ex vivo sickling. In conclusion, severity of anemia in SCD is improved with amiodarone treatment, an effect which may be mediated through increased erythrocyte BMP.

Benznidazole and amiodarone combined treatment attenuates cytoskeletal damage in Trypanosoma cruzi-infected cardiac cells.

Chagas disease (CD), a neglected tropical disease caused by the protozoan parasite Trypanosoma cruzi, is an important public health problem mainly in Latin America, leading to approximately 12,000 annual deaths. Current etiological treatment for CD is limited to two nitro compounds, benznidazole (Bz) and nifurtimox (Nif), both presenting relevant limitations. Different approaches have been employed to establish more effective and safer schemes to treat T. cruzi infection, mostly based on drug repurposing and combination therapies. Amiodarone (AMD), an antiarrhythmic medicament of choice for patients with the chronic cardiac form of CD, is also recognized as a trypanocidal agent. Therefore, our aim is to investigate the combined treatment Bz + AMD on trypomastigote viability, control of T. cruzi intracellular form proliferation, and recovery of the infection-induced cytoskeleton alterations in cardiac cells. The combination of Bz + AMD did not improve the direct trypanocidal effect of AMD on the infective blood trypomastigote and replicative intracellular forms of the parasite. Otherwise, the treatment of T. cruzi-infected cardiac cells with Bz plus AMD attenuated the infection-triggered cytoskeleton damage of host cells and the cytotoxic effects of AMD. Thus, the combined treatment Bz + AMD may favor parasite control and hamper tissue damage.

The effects of amiodarone in ovarian injury due to oxidative stress and inflammation caused by ischemia-reperfusion.

OBJECTIVE: Ovarian ischemia constitutes 2-3% of all gynecological emergencies. New-generation therapeutic agents need to be discovered, in addition to invasive interventions capable of reducing the risk of potential ovarian ischemia to a minimum and protecting against potential adverse outcomes. AIMS: To investigate the effects of amiodarone (AMD) on ischemia-reperfusion-induced oxidative stress and inflammation-induced ovarian damage. METHODS: The control group, received intraperitoneal (i.p.) injection of saline solution. The ischemia group (I-Group), was subjected to ischemia-induced injury without drug administration. The ischemia + AMD (50 mg/kg) group was subjected to ischemia injury and also received i.p. 50 mg/kg AMD prior to induction of ovarian ischemia. The ischemia-reperfusion (I/R group) was exposed to ischemia and reperfusion-induced injury without drug administration. The I/R + AMD (50 mg/kg) group underwent I/R injury together with i.p. administration of 50 mg/kg AMD prior to induction of ovarian I/R. The Sham + AMD group received intraperitoneal (i.p.) injection of 50 mg/kg AMD alone. In this study performed thiobarbituric acid reactive substances (TBARS), thiol (-SH), interleukin 1 Beta (IL-1ß), interleukin 6 (IL-6), toll-like receptor 4 (TLR4) and nuclear factor-kappa B(NF-κß). RESULTS: Increased oxidative stress and inflammation as a result of ovarian I and I/R application activated the cascade. AMD was not sufficient to reduce the oxidative stress and inflammation. TLR4 and NF-kß, which were up-regulated by triggering oxidative stress and inflammation, were not regressed by the effects of AMD. CONCLUSIONS: AMD, used as an antiarrhythmic agent, was found to be insufficient, despite its antioxidant and anti-inflammatory properties, to reduce the experimentally induced ovarian tissue damage.

Effects of amiodarone, amioder, and dronedarone on Trichomonas vaginalis.

Trichomonas vaginalis is a protozoan that causes human trichomoniasis, the most common non-viral sexually transmitted infection (STI) affecting approximately 278 million people worldwide. The current treatment for trichomoniasis is based on 1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole, known as metronidazole (MTZ). Although effective in clearing the parasite infection, MTZ is related to provoking severe side effects, and it is not recommended during pregnancy. In addition, some strains present resistance to 5'-nitroimidazoles, making urgent the development of alternative drugs for trichomoniasis. Amiodarone, an antiarrhythmic drug, exerts a significant anti-parasite effect, mainly due to its interference with calcium homeostasis and the biosynthesis of sterols. Therefore, we decided to test the effect of amiodarone and two other related compounds (amioder and dronedarone) on T. vaginalis. Our observations show that amiodarone stimulated, rather than inhibited, parasite growth, induced cell aggregation, and glycogen accumulation. Furthermore, the other two compounds displayed anti-parasite activity with IC50 of 3.15 and 11 µM, respectively, and the apoptosis-like process killed the cells. In addition, cells exhibited morphological changes, including an effect on hydrogenosomes structure.

Experimental Combination Therapy with Amiodarone and Low-Dose Benznidazole in a Mouse Model of Trypanosoma cruzi Acute Infection.

Chagas disease (CD), caused by Trypanosoma cruzi, affects approximately 6 to 7 million people in Latin America, with cardiomyopathy being the clinical manifestation most commonly associated with patient death during the acute phase. The etiological treatment of CD is restricted to benznidazole (Bz) and nifurtimox (Nif), which involve long periods of administration, frequent side effects, and low efficacy in the chronic phase. Thus, combined therapies emerge as an important tool in the treatment of CD, allowing the reduction of Bz dose and treatment duration. In this sense, amiodarone (AMD), the most efficient antiarrhythmic drug currently available and prescribed to CD patients, is a potential candidate for combined treatment due to its known trypanocidal activity. However, the efficacy of AMD during the acute phase of CD and its interaction with Bz or Nif are still unknown. In the present study, using a well-established murine model of the acute phase of CD, we observed that the Bz/AMD combination was more effective in reducing the peak parasitemia than both monotherapy treatments. Additionally, the Bz/AMD combination reduced (i) interleukin-6 (IL-6) levels in cardiac tissue, (ii) P-wave duration, and (iii) frequency of arrhythmia in infected animals and (iv) restored gap junction integrity in cardiac tissue. Therefore, our study validates AMD as a promising candidate for combined therapy with Bz, reinforcing the strategy of combined therapy for CD. IMPORTANCE Chagas disease affects approximately 6 to 7 million people worldwide, with cardiomyopathy being the clinical manifestation that most commonly leads to patient death. The etiological treatment of Chagas disease is limited to drugs (benznidazole and nifurtimox) with relatively high toxicity and therapeutic failures. In this sense, amiodarone, the most effective currently available antiarrhythmic drug prescribed to patients with Chagas disease, is a potential candidate for combined treatment due to its known trypanocidal effect. In the present study, we show that combined treatment with benznidazole and amiodarone improves the trypanocidal effect and reduces cardiac damage in acutely T. cruzi-infected mice.

Effectiveness of amiodarone versus digitalis for heart rate control in critically ill patients with new-onset atrial fibrillation.

New-onset of atrial fibrillation (NOAF) in critically ill patients is the most common acute cardiac dysrhythmia, but evidence-based data regarding treatment strategies are scarce. In this retrospective monocentric study, we compared effectiveness of amiodarone versus digitalis for heart rate control in critically ill patients with new-onset of atrial fibrillation. We identified a total of 209 patients for the main analysis. Amiodarone as compared to digitalis was associated with a clinically relevant faster time to heart rate control < 110 bpm (2 h (IQR: 1 h to 6 h) versus 4 h (2 h to 12 h); p = 0.003) and longer durations of sinus rhythm during the first 24 h of treatment (6 h (IQR: 6 h to 22 h) versus 0 h (IQR: 0 h to 16 h); p < 0.001). However, more bradycardic episodes occurred in association with amiodarone than with digitalis (7.7% versus 3.4%; p = 0.019). Use of amiodarone was associated with an increase of noradrenalin infusion rate compared to digitalis (23.9% versus 12.0%; p = 0.019). Within the tertile of patients with the highest CRP measurements, amiodarone treated patients presented with a higher decrease in heart rate than digoxin treated patients. Clinical trials comparing different NOAF treatment strategies are much needed and should report on concomitant sympathetic activity and inflammatory status.