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Electrophoresis May 2022Cardiac glycosides digoxin and digitoxin are used in therapy for the treatment of congestive heart failure. Moreover, these compounds can be responsible for intoxication...
Development of a new ultra-high-performance liquid chromatography-tandem mass spectrometry method for the determination of digoxin and digitoxin in plasma: Comparison with a clinical immunoassay.
Cardiac glycosides digoxin and digitoxin are used in therapy for the treatment of congestive heart failure. Moreover, these compounds can be responsible for intoxication cases caused by fortuitous ingestion of leaves of Digitalis. Due to the narrow therapeutic range of these drugs, therapeutic drug monitoring is recommended in the clinical practice. In this context, immunoassays-based methods are generally employed but digoxin- and digitoxin-like compounds can interfere with the analysis. The aim of this study was to develop and validate an original UPLC-MS/MS method for the determination of digoxin and digitoxin in plasma. The method shows adequate sensitivity and selectivity with acceptable matrix effects and very good linearity, accuracy, precision, and recovery. A simple liquid-liquid extraction procedure was used for sample clean-up. The method was applied for the analysis of n = 220 plasma samples collected in two different clinical chemistry laboratories and previously tested by the same immunoassay. The statistical comparison showed a relevant negative bias of the UPLC-MS/MS method versus the immunoassay. These results are consistent with an immunoassay overestimation of digoxin plasmatic levels due to cross-reaction events with endogenous digoxin-like substances.
Topics: Chromatography, High Pressure Liquid; Chromatography, Liquid; Digitoxin; Digoxin; Immunoassay; Tandem Mass Spectrometry
PubMed: 35132652
DOI: 10.1002/elps.202100290 -
Contemporary Clinical Trials Nov 2020The COVID-19 pandemic has substantially impacted the conduct of clinical trials. While initially preparing for a period of time, where it would likely be impossible to...
The COVID-19 pandemic has substantially impacted the conduct of clinical trials. While initially preparing for a period of time, where it would likely be impossible to supervise trials in the usual way and precautionary measures had to be implemented to care for medication supply and general safety of study participants it is now important to consider, how the impact of the pandemic on trial outcome can be assessed, which measures are needed to decide, how to proceed with the trial and what is needed to compensate to irregularity introduced by the pandemic situation. Obviously not all trials will suffer to the same degree: some trials may be close to finalizing recruitment, others may not yet have started. Similarly not all clinical trials investigate vulnerable patient populations, but some will and may in addition have recruited to an extent that beneficial effects achieved in the initial phase of the trial may be outweighed by an increase e.g. in mortality that impacts both treatment groups. The situation is further complicated by the fact that the pandemic reached different countries in the world and even cities in one country at different points in time with different severity. Our example is a randomized and double-blind clinical trial comparing digitoxin and placebo in patients with advanced chronic heart failure. This trial has recruited roughly 1/3 of the overall 2200 patients when the disease outbreak reached Germany. We discuss how simulations and theoretical considerations can be used to address questions about the need to increase the overall sample-size to be recruited to compensate for a potential shrinkage of the treatment effect caused by the COVID-19 pandemic and what role the degree of consistency could play when comparing pre-, during- and post- COVID-19 periods of trial conduct regarding the question, whether the treatment effect can be considered consistent and with this generalizable. This is dependent on the size of the treatment effect and the impact of the pandemic. We argue, that in case of doubt, it may be wise to proceed with the original study plan.
Topics: COVID-19; Clinical Trials as Topic; Early Termination of Clinical Trials; Germany; Global Health; Humans; Infection Control; Organizational Innovation; Outcome Assessment, Health Care; Randomized Controlled Trials as Topic; Research Design; SARS-CoV-2; Sample Size; Vulnerable Populations
PubMed: 32961360
DOI: 10.1016/j.cct.2020.106155 -
Scientific Reports Nov 2021To initiate SARS-CoV-2 infection, the Receptor Binding Domain (RBD) on the viral spike protein must first bind to the host receptor ACE2 protein on pulmonary and other...
To initiate SARS-CoV-2 infection, the Receptor Binding Domain (RBD) on the viral spike protein must first bind to the host receptor ACE2 protein on pulmonary and other ACE2-expressing cells. We hypothesized that cardiac glycoside drugs might block the binding reaction between ACE2 and the Spike (S) protein, and thus block viral penetration into target cells. To test this hypothesis we developed a biochemical assay for ACE2:Spike binding, and tested cardiac glycosides as inhibitors of binding. Here we report that ouabain, digitoxin, and digoxin, as well as sugar-free derivatives digitoxigenin and digoxigenin, are high-affinity competitive inhibitors of ACE2 binding to the Original [D614] S1 and the α/β/γ [D614G] S1 proteins. These drugs also inhibit ACE2 binding to the Original RBD, as well as to RBD proteins containing the β [E484K], Mink [Y453F] and α/β/γ [N501Y] mutations. As hypothesized, we also found that ouabain, digitoxin and digoxin blocked penetration by SARS-CoV-2 Spike-pseudotyped virus into human lung cells, and infectivity by native SARS-CoV-2. These data indicate that cardiac glycosides may block viral penetration into the target cell by first inhibiting ACE2:RBD binding. Clinical concentrations of ouabain and digitoxin are relatively safe for short term use for subjects with normal hearts. It has therefore not escaped our attention that these common cardiac medications could be deployed worldwide as inexpensive repurposed drugs for anti-COVID-19 therapy.
Topics: A549 Cells; Angiotensin-Converting Enzyme 2; Animals; COVID-19; Cardiotonic Agents; Chlorocebus aethiops; Digitoxin; Digoxin; Humans; Lung; Ouabain; Protein Binding; SARS-CoV-2; Spike Glycoprotein, Coronavirus; Vero Cells; Virus Internalization; COVID-19 Drug Treatment
PubMed: 34773067
DOI: 10.1038/s41598-021-01690-9 -
Frontiers in Oncology 2019Castration Resistant Prostate Cancer (CRPC) is thought to be driven by a collaborative mechanism between TNFα/NFκB and TGFβ signaling, leading to inflammation,...
Castration Resistant Prostate Cancer (CRPC) is thought to be driven by a collaborative mechanism between TNFα/NFκB and TGFβ signaling, leading to inflammation, Epithelial-to-Mesenchymal-Transition (EMT), and metastasis. Initially, TGFβ is a tumor suppressor, but in advanced metastatic disease it switches to being a tumor promoter. TGFBR2 may play a critical role in this collaboration, as its expression is driven by NFκB and it is the primary receptor for TGFβ. We have previously reported that the cardenolide drug digitoxin blocks TNFα/NFκB-driven proinflammatory signaling. We therefore hypothesized that digitoxin might break the collaborative process between NFκB and TGFβ by also inhibiting expression of TGFBR2. We therefore tested whether TGFβ-driven EMT and resulting metastases would be suppressed. Here we show, , that digitoxin inhibits NFκB-driven TGFBR2 expression, as well as Vimentin, while elevating E-cadherin expression. Digitoxin also significantly reduces HSPB1 mRNA and the HSPB1/RBFOX2 mRNA ratio in PC3 cells. , in a syngeneic, immune competent rat model of metastatic CRPC, we show that digitoxin also suppresses expression, as well as expression of other genes classically driven by NFκB, and of multiple EMT genes associated with metastasis. Concurrently, digitoxin suppresses tumor growth and metastasis in these animals, and prolongs survival. Gross tumor recurrence following tumor resection also appears prevented in 30% of cases. While the existence of a collaboration between NFκB and TGFβ to drive EMT and metastasis has previously been appreciated, we show here, for the first time, that chronic, low concentrations of digitoxin are able to block CRPC tumor progression, EMT and the ensuing metastatic disease.
PubMed: 31428571
DOI: 10.3389/fonc.2019.00630 -
Molecular Pharmacology Mar 2021Recent studies have revealed that Na/K-ATPase (NKA) can transmit signals through ion-pumping-independent activation of pathways relayed by distinct intracellular...
Recent studies have revealed that Na/K-ATPase (NKA) can transmit signals through ion-pumping-independent activation of pathways relayed by distinct intracellular protein/lipid kinases, and endocytosis challenges the traditional definition that cardiotonic steroids (CTS) are NKA inhibitors. Although additional effects of CTS have long been suspected, revealing its agonist impact through the NKA receptor could be a novel mechanism in understanding the basic biology of NKA. In this study, we tested whether different structural CTS could trigger different sets of NKA/effector interactions, resulting in biased signaling responses without compromising ion-pumping capacity. Using purified NKA, we found that ouabain, digitoxigenin, and somalin cause comparable levels of NKA inhibition. However, although endogenous ouabain stimulates both protein kinases and NKA endocytosis, digitoxigenin and somalin bias to protein kinases and endocytosis, respectively, in LLC-PK1 cells. The positive inotropic effects of CTS are traditionally regarded as NKA inhibitors. However, CTS-induced signaling occurs at concentrations at least one order of magnitude lower than that of inotropy, which eliminates their well known toxic actions on the heart. The current study adds a novel mechanism that CTS could exert its biased signaling properties through the NKA signal transducer. SIGNIFICANCE STATEMENT: Although it is now well accepted that NKA has an ion-pumping-independent signaling function, it is still debated whether direct and conformation-dependent NKA/effector interaction is a key to this function. Therefore, this investigation is significant in advancing our understanding of the basic biology of NKA-mediated signal transduction and gaining molecular insight into the structural elements that are important for cardiotonic steroid's biased action.
Topics: Animals; Cardiac Glycosides; Cell Survival; Digitoxigenin; Gene Expression Regulation; Glycosides; LLC-PK1 Cells; Ouabain; Signal Transduction; Sodium-Potassium-Exchanging ATPase; Swine
PubMed: 33495275
DOI: 10.1124/molpharm.120.000101 -
Respiratory Research Dec 2019Several small molecule corrector and potentiator drugs have recently been licensed for Cystic Fibrosis (CF) therapy. However, other aspects of the disease, especially...
BACKGROUND
Several small molecule corrector and potentiator drugs have recently been licensed for Cystic Fibrosis (CF) therapy. However, other aspects of the disease, especially inflammation, are less effectively treated by these drugs. We hypothesized that small molecule drugs could function either alone or as an adjuvant to licensed therapies to treat these aspects of the disease, perhaps emulating the effects of gene therapy in CF cells. The cardiac glycoside digitoxin, which has been shown to inhibit TNFα/NFκB signaling in CF lung epithelial cells, may serve as such a therapy.
METHODS
IB3-1 CF lung epithelial cells were treated with different Vertex (VX) drugs, digitoxin, and various drug mixtures, and ELISA assays were used to assess suppression of baseline and TNFα-activated secretion of cytokines and chemokines. Transcriptional responses to these drugs were assessed by RNA-seq and compared with gene expression in AAV-[wildtype]CFTR-treated IB3-1 (S9) cells. We also compared in vitro gene expression signatures with in vivo data from biopsied nasal epithelial cells from digitoxin-treated CF patients.
RESULTS
CF cells exposed to digitoxin exhibited significant suppression of both TNFα/NFκB signaling and downstream secretion of IL-8, IL-6 and GM-CSF, with or without co-treatment with VX drugs. No evidence of drug-drug interference was observed. RNA-seq analysis showed that gene therapy-treated CF lung cells induced changes in 3134 genes. Among these, 32.6% were altered by digitoxin treatment in the same direction. Shared functional gene ontology themes for genes suppressed by both digitoxin and gene therapy included inflammation (84 gene signature), and cell-cell interactions and fibrosis (49 gene signature), while genes elevated by both were enriched for epithelial differentiation (82 gene signature). A new analysis of mRNA data from digitoxin-treated CF patients showed consistent trends in expression for genes in these signatures.
CONCLUSIONS
Adjuvant gene therapy-emulating activities of digitoxin may contribute to enhancing the efficacy of currently licensed correctors and potentiators in CF patients.
Topics: Animals; Cardiotonic Agents; Cells, Cultured; Cystic Fibrosis; Digitoxin; Dose-Response Relationship, Drug; Genetic Therapy; Humans; Inflammation Mediators; Rats; Rats, Inbred F344; Respiratory Mucosa; Treatment Outcome
PubMed: 31864360
DOI: 10.1186/s12931-019-1214-8 -
Frontiers in Pharmacology 2021Drugs commonly prescribed for heart rate control may induce adverse drug reactions in Alzheimer patients treated with acetylcholinesterase inhibitors (AChEIs). We have...
Use of Drugs With Risk of Heart Rate-Related Problems is Common in Norwegian Dementia Patients Treated With Acetylcholinesterase Inhibitors: A Prevalence Study Based on the Norwegian Prescription Database.
Drugs commonly prescribed for heart rate control may induce adverse drug reactions in Alzheimer patients treated with acetylcholinesterase inhibitors (AChEIs). We have studied use of drugs with a known risk of Torsades de pointes (TdP) and drugs used to treat behavioral and psychological symptoms of dementia, as well as a combination of drugs with a known risk of TdP and drugs with a known heart rate-lowering effect, before and after initiating treatment with AChEIs. The study applied data from the Norwegian Prescription Database for the period 2004-2016. Prescriptions of concomitant use of drugs in persistent users of AChEIs was studied in a follow-up period from 4 years before to 2 years after AChEI initiation in men and women of two age groups: 37-80 and 81-88 years. A small number of patients were prescribed haloperidol (∼1.5% The second year after AChEI initiation), digoxin/digitoxin (∼3%), and verapamil (∼1.3%), while a substantial proportion of the patients were prescribed betablockers (∼28%) and citalopram/escitalopram (∼17%). During follow-up, up to 6% of the study population were prescribed both betablockers and citalopram/citalopram in addition to AChEIs, a combination that increased over the follow-up period and was observed most frequently in women in the oldest age group. A large proportion (∼44%) of patients treated with AChEIs were prescribed drugs that could cause bradycardic and prolonged time from the start of the Q wave to the end of the T wave (QT interval). Thus, action should be taken to reduce the combination of drugs with risk of bradycardia and prolonged QT interval. Medication review on a regular basis could be an option as an important risk-reducing intervention.
PubMed: 35273492
DOI: 10.3389/fphar.2021.791578 -
Pharmaceutics Jun 2023Decoration of nanoparticles with specific molecules such as antibodies, peptides, and proteins that preserve their biological properties is essential for the recognition...
Decoration of nanoparticles with specific molecules such as antibodies, peptides, and proteins that preserve their biological properties is essential for the recognition and internalization of their specific target cells. Inefficient preparation of such decorated nanoparticles leads to nonspecific interactions diverting them from their desired target. We report a simple two-step procedure for the preparation of biohybrid nanoparticles containing a core of hydrophobic quantum dots coated with a multilayer of human serum albumin. These nanoparticles were prepared by ultra-sonication, crosslinked using glutaraldehyde, and decorated with proteins such as human serum albumin or human transferrin in their native conformations. These nanoparticles were homogeneous in size (20-30 nm), retained the fluorescent properties of quantum dots, and did not show a "corona effect" in the presence of serum. The uptake of transferrin-decorated quantum dot nanoparticles was observed in A549 lung cancer and SH-SY5Y neuroblastoma cells but not in non-cancerous 16HB14o- or retinoic acid dopaminergic neurons differentiated SH-SY5Y cells. Furthermore, digitoxin-loaded transferrin-decorated nanoparticles decreased the number of A549 cells without effect on 16HB14o-. Finally, we analyzed the in vivo uptake of these biohybrids by murine retinal cells, demonstrating their capacity to selectively target and deliver into specific cell types with excellent traceability.
PubMed: 37376099
DOI: 10.3390/pharmaceutics15061651 -
Biomedicine & Pharmacotherapy =... Aug 2022Several mediators including cytokines, growth factors and metalloproteinases (MMP) modulate pathological angiogenesis associated with inflammatory arthritis. The...
Several mediators including cytokines, growth factors and metalloproteinases (MMP) modulate pathological angiogenesis associated with inflammatory arthritis. The biological factors underlying sex disparities in the incidence and severity of rheumatic musculoskeletal diseases are only partially understood. We hypothesized that synovial fluids (SFs) from rheumatoid arthritis (RA) and psoriatic arthritis (PsA) patients would impact on endothelial biology in a sexually dimorphic fashion. Immune cell counts and levels of pro-angiogenic cytokines found in SFs from RA and PsA patients (n = 17) were higher than in osteoarthritis patients (n = 6). Synovial VEGF concentration was significantly higher in male than in female RA patients. Zymography revealed that SFs comprised solely MMP-9 and MMP-2, with significantly higher MMP-9 levels in male than female RA patients. Using in vitro approaches that mimic the major steps of the angiogenic process, SFs from RA and PsA patients induced endothelial migration and formation of capillary-like structures compared to control. Notably, endothelial cells from female donors displayed enhanced angiogenic response to SFs with respect to males. Treatment with the established anti-angiogenic agent digitoxin prevented activation of focal adhesion kinase and SF-induced in vitro angiogenesis. Thus, despite higher synovial VEGF and MMP-9 levels in male patients, the responsiveness of vascular endothelium to SF priming was higher in females, suggesting that gender differences in angiogenic responses were mainly related to the endothelial genotype. These findings may have implications for pathogenesis and targeted therapies of inflammatory arthritis.
Topics: Arthritis, Psoriatic; Arthritis, Rheumatoid; Cytokines; Endothelial Cells; Female; Humans; Male; Matrix Metalloproteinase 9; Neovascularization, Pathologic; Sex Factors; Synovial Fluid; Synovial Membrane; Vascular Endothelial Growth Factor A
PubMed: 35653890
DOI: 10.1016/j.biopha.2022.113181 -
Drugs - Real World Outcomes Jun 2023Cardiac glycosides such as digoxin, digitoxin and ouabain are still used around the world to treat patients with chronic heart failure with reduced ejection fraction...
BACKGROUND
Cardiac glycosides such as digoxin, digitoxin and ouabain are still used around the world to treat patients with chronic heart failure with reduced ejection fraction (HFrEF) and/or atrial fibrillation (AF). However, in the US, only digoxin is licensed for treating these illnesses, and the use of digoxin for this group of patients is increasingly being replaced in the US by a new standard of care with groups of more expensive drugs. However, ouabain and digitoxin, and less potently digoxin, have also recently been reported to inhibit SARS-CoV-2 virus penetration into human lung cells, thus blocking COVID-19 infection. COVID-19 is known to be a more aggressive disease in patients with cardiac comorbidities, including heart failure.
OBJECTIVE
We therefore considered the possibility that digoxin might provide at least a measure of relief from COVID-19 in digoxin-treated heart failure patients. To this end, we hypothesized that treatment with digoxin rather than standard of care might equivalently protect heart failure patients with regard to diagnosis of COVID-19, hospitalization and death.
METHODS
To test this hypothesis, we conducted a cross-sectional study by using the US Military Health System (MHS) Data Repository to identify all MHS TRICARE Prime and Plus beneficiaries aged 18-64 years with a heart failure (HF) diagnosis during the period April 2020 to August 2021. In the MHS, all patients receive equal, optimal care without regard to rank or ethnicity. Analyses included descriptive statistics on patient demographics and clinical characteristics, and logistic regressions to determine likelihood of digoxin use.
RESULTS
We identified 14,044 beneficiaries with heart failure in the MHS during the study period. Of these, 496 were treated with digoxin. However, we found that both digoxin-treated and standard-of-care groups were equivalently protected from COVID-19. We also noted that younger active duty service members and their dependents with HF were less likely to receive digoxin compared with older, retired beneficiaries with more comorbidities.
CONCLUSION
The hypothesis of equivalent protection by digoxin treatment of HF patients in terms of susceptibility to COVID-19 infection appears to be supported by the data.
PubMed: 36933173
DOI: 10.1007/s40801-023-00360-8