Effects of donepezil on hERG potassium channels

Cholinesterase inhibitors-associated torsade de pointes/QT prolongation: a real-world pharmacovigilance study

Objective: Cholinesterase inhibitor (ChEIs) is the first-line drug for Alzheimer's disease (AD). Understanding torsade de pointes (TdP)/QT prolongation with different ChEIs is essential for its safe and rational administration. This study aimed to evaluate the correlation between different ChEIs and TdP/QT prolongation. Methods: All ChEIs related TdP/QT prolongation cases were retrieved from the FAERS database using standard MedDRA query (SMQ) from the first quarter of 2004 to the third quarter of 2022. Disproportionality and sensitivity analysis were used to determine the signal of TdP/QT prolongation related to ChEIs. Results: 557 cases of TdP/QT prolongation related to 3 ChEIs were searched by SMQ. The patients were mostly elderly people, with markedly more female than male. The signals of TdP/QT prolongation for ChEIs were detected by disproportionality analysis, and the signal of Donepezil was the strongest. The sensitivity analysis results indicate a robust and stable correlation between these signals with ChEIs. TdP/QT prolongation usually occurs within 1 month after taking ChEIs. The drug with the highest frequency of combination with donepezil and galantamine is citalopram, and the drug with the highest frequency of combination with rivastigmine is atorvastatin. Conclusion: The signals of TdP/QT prolongation related to ChEIs were strong and stable. It is necessary to be vigilant about the TdP/QT prolongation of various ChEIs, especially in elderly women, the initial stage after taking ChEIs, and when ChEIs combining with drugs that could prolong the QT interval.

Structure-based design of new N-benzyl-piperidine derivatives as multitarget-directed AChE/BuChE inhibitors for Alzheimer's disease

The pathogenic complexity of Alzheimer's disease (AD) demands the development of multitarget-directed agents aiming at improving actual pharmacotherapy. Based on the cholinergic hypothesis and considering the well-established role of butyrylcholinesterase (BuChE) in advanced stages of AD, the chemical structure of the acetylcholinesterase (AChE) inhibitor drug donepezil (1) was rationally modified for the design of new N-benzyl-piperidine derivatives (4a-d) as potential multitarget-direct AChE and BuChE inhibitors. The designed analogues were further studied through the integration of in silico and in vitro methods. ADMET predictions showed that 4a-d are anticipated to be orally bioavailable, able to cross the blood-brain barrier and be retained in the brain, and to have low toxicity. Computational docking and molecular dynamics indicated the formation of favorable complexes between 4a-d and both cholinesterases. Derivative 4a presented the lowest binding free energy estimation due to interaction with key residues from both target enzymes (-36.69 ± 4.47 and -32.23 ± 3.99 kcal/mol with AChE and BuChE, respectively). The in vitro enzymatic assay demonstrated that 4a was the most potent inhibitor of AChE (IC50 2.08 ± 0.16 µM) and BuChE (IC50 7.41 ± 0.44 µM), corroborating the in silico results and highlighting 4a as a novel multitarget-directed AChE/BuChE inhibitor.

Alzheimer's disease therapy based on acetylcholinesterase inhibitor/blocker effects on voltage-gated potassium channels

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder with progressive loss of memory and other cognitive functions. The pathogenesis of this disease is complex and multifactorial, and remains obscure until now. To enhance the declined level of acetylcholine (ACh) resulting from loss of cholinergic neurons, acetylcholinesterase (AChE) inhibitors are developed and successfully approved for AD treatment in the clinic, with a limited therapeutic effectiveness. At present, it is generally accepted that multi-target strategy is potently useful for designing novel drugs for AD. Accumulated evidence reveals that Kv channels, which are broadly expressed in brain and possess crucial functions in modulating the neuronal activity, are inhibited by several acetylcholinesterase (AChE) inhibitors, such as tacrine, bis(7)-tacrine, donepezil and galantamine. Inhibition of Kv channels by these AChE inhibitors can generate neuroprotective effects by either mitigating Aβ toxicity and neuronal apoptosis, or facilitating cell proliferation. These inhibitory effects provide additional explanations for clinical beneficial effectiveness of AChE inhibitors, meaning that Kv channel is a promising candidate target for novel drugs for AD therapy.

Detecting drug-drug interactions that increase the incidence of long QT syndrome using a spontaneous reporting system

WHAT IS KNOWN AND OBJECTIVE

Drug-induced long QT syndrome (diLQTS) is a rare but serious adverse drug reaction. Drug-drug interaction (DDI) is one of the risk factors for the development of diLQTS. However, the combinations of drugs that increase the risk of diLQTS have not been extensively investigated. This study was performed to analyse the potential DDIs that elevate the incidence of diLQTS using a spontaneous reporting system.

METHODS

The Japanese Adverse Drug Event Report database from April 2004 to January 2020 was used to assess adverse event reports. We calculated the reporting odds ratio and 95% confidence interval for signal detection.

RESULTS AND DISCUSSION

Signals for concomitant use risk were detected in 31 drug combinations. Combinations of antipsychotics and antidepressants were the most common (olanzapine & fluvoxamine, olanzapine & trazodone, quetiapine & paroxetine, sulpiride & fluvoxamine, sulpiride & trazodone). Sixteen, 17 and 21 combinations were designated as requiring precaution for concomitant use in at least one of the package inserts in Japan, the United States and the United Kingdom, respectively, although no such precautions were described for the remaining combinations. On the contrary, a combination of bepridil & clarithromycin was categorized as "X (avoid combination)" and two combinations (chlorpromazine & haloperidol, amiodarone & metildigoxin) were classified as "D (modify regimen)" in the Lexicomp^® risk rating.

WHAT IS NEW AND CONCLUSION

This study identified 31 combinations of drugs that may elevate the risk of diLQTS. The use of these drug combinations should be monitored more carefully in future.

High-Throughput Drug Screening System Based on Human Induced Pluripotent Stem Cell-Derived Atrial Myocytes ∼ A Novel Platform to Detect Cardiac Toxicity for Atrial Arrhythmias

Evaluation of proarrhythmic properties is critical for drug discovery. In particular, QT prolongation in electrocardiograms has been utilized as a surrogate marker in many evaluation systems to assess the risk of torsade de pointes and lethal ventricular arrhythmia. Recently, new evaluation systems based on human iPS cell-derived cardiomyocytes have been established. On the other hand, in clinical situations, it has been reported that the incidence of atrial arrhythmias such as atrial fibrillation has been increasing every year, with the prediction of a persistent increase in the near future. As to the increased incidence of atrial arrhythmias, in addition to the increased population of geriatric patients, a wide variety of drug treatments may be related, as an experimental method to detect drug-induced atrial arrhythmia has not been established so far. In the present study, we characterized the atrial-like cardiomyocytes derived from human induced pluripotent stem cells and examined their potential for the evaluation of drug-induced atrial arrhythmia. Atrial-like cardiomyocytes were induced by adding retinoic acid (RA) during the process of myocardial differentiation, and their characteristics were compared to those of RA-free cardiomyocytes. Using gene expression and membrane potential analysis, it was confirmed that the cells with or without RA treatment have atrial or ventricular like cardiomyocytes, respectively. Using the ultra-rapid activating delayed rectifier potassium current (I_Kur) channel inhibitor, which is specific to atrial cardiomyocytes, Pulse width duration (PWD) 30cF prolongation was confirmed only in atrial-like cardiomyocytes. In addition, ventricular like cardiomyocytes exhibited an early after depolarization by treatment with rapidly activating delayed rectifier potassium current (I_Kr) channel inhibitor, which induces ventricular arrhythmia in clinical situations. Here, we have established a high-throughput drug evaluation system using human iPS cell-derived atrial-like cardiomyocytes. Based on the obtained data, the system might be a valuable platform to detect potential risks for drug-induced atrial arrhythmias.

Cardiac hERG K+ Channel as Safety and Pharmacological Target

The human ether-á-go-go related gene (hERG, KCNH2) encodes the pore-forming subunit of the potassium channel responsible for a fast component of the cardiac delayed rectifier potassium current (I_Kr). Outward I_Kr is an important determinant of cardiac action potential (AP) repolarization and effectively controls the duration of the QT interval in humans. Dysfunction of hERG channel can cause severe ventricular arrhythmias and thus modulators of the channel, including hERG inhibitors and activators, continue to attract intense pharmacological interest. Certain inhibitors of hERG channel prolong the action potential duration (APD) and effective refractory period (ERP) to suppress premature ventricular contraction and are used as class III antiarrhythmic agents. However, a reduction of the hERG/I_Kr current has been recognized as a predominant mechanism responsible for the drug-induced delayed repolarization known as acquired long QT syndromes (LQTS), which is linked to an increased risk for "torsades de pointes" (TdP) ventricular arrhythmias and sudden cardiac death. Many drugs of different classes and structures have been identified to carry TdP risk. Hence, assessing hERG/I_Kr blockade of new drug candidates is mandatory in the drug development process according to the regulatory agencies. In contrast, several hERG channel activators have been shown to enhance I_Kr and shorten the APD and thus might have potential antiarrhythmic effects against pathological LQTS. However, these activators may also be proarrhythmic due to excessive shortening of APD and the ERP.

QT interval prolongation and Torsades de Pointes with donepezil, rivastigmine and galantamine

Background

Acetylcholinesterase inhibitors (AChEis) including donepezil, galantamine and rivastigmine are used to treat Alzheimer's disease (AD). This study aimed to evaluate evidence from the case report literature for an association between these agents and risk of QT interval prolongation and Torsades de Pointes (TdP) arrhythmia.

Methods

Published literature was mined with predetermined MeSH terms for each of donepezil, galantamine and rivastigmine, to identify cases of QT interval prolongation and TdP. Case reports were analysed using causality scales and a QT interval nomogram.

Results

A total of 13 case reports were found (10 for donepezil, 2 for galantamine and 1 for rivastigmine) with rate corrected QT interval (QT_c) prolongation. Five cases with donepezil exhibited TdP. TdP was not reported in the cases with galantamine and rivastigmine. The use of a QT heart rate nomogram highlighted risk with donepezil compared with the other two drugs and the application of the Naranjo causality scale suggested probable or possible causation for all donepezil cases. All patients had at least two other risk factors for TdP, including modifiable risk factors such as electrolyte disturbances, bradycardia, co-administration of QT prolonging drugs. A number of recent cases involved recent changes in medication.

Conclusion

Our evaluation of the case report literature suggests that there is evidence for a causal association between donepezil and QT_c/TdP risk. Attention to risk factors for QT_c prolongation/TdP should be exercised when prescribing donepezil and modifiable risk factors corrected. Owing to the low number of cases with galantamine and rivastigmine, further work is needed to establish whether these drugs may be more suitable than donepezil for patients with other risk factors for TdP.

Comparative risk of cardiac arrhythmias associated with acetylcholinesterase inhibitors used in treatment of dementias - A narrative review

Donepezil, galantamine, and rivastigmine are the three acetylcholinesterase inhibitors (AChEIs), out of a total of only four medications prescribed in the treatment of Alzheimer's Disease (AD) and related dementias. These medications are known to be associated with bradycardia given their mechanism of action of increasing acetylcholine (ACh). However, in March 2015, donepezil was added to the CredibleMeds "known-risk" category, a list where medications have a documented risk for acquired long-QT syndrome (ALQTS) and torsades de pointes (TdP) - a malignant ventricular arrhythmia that is a different adverse event than bradycardia (and is not necessarily associated with ACh action). The purpose of this article is to review the three AChEIs, especially with regards to mechanistic differences that may explain why only donepezil poses this risk; several pharmacological mechanisms may explain why. However, from an empirical point-of-view, aside from some case-reports, only a limited number of studies have generated relevant information regarding AChEIs' and electrocardiogram findings; none have specifically compared donepezil against galantamine or rivastigmine for malignant arrhythmias such as TdP. Currently, the choice of one of the three AChEIs for treatment of AD symptoms is primarily dependent upon clinician and patient preference. However, clinicians should be aware of the potential increased risk associated with donepezil. There is a need to examine the comparative risk of malignant arrhythmias among AChEIs users in real-world practice; this may have important implications with regards to changes in AChEI prescribing patterns.

Pharmacogenetic considerations when prescribing cholinesterase inhibitors for the treatment of Alzheimer's disease

INTRODUCTION

Cholinergic dysfunction, demonstrated in the late 1970s and early 1980s, led to the introduction of acetylcholinesterase inhibitors (AChEIs) in 1993 (Tacrine) to enhance cholinergic neurotransmission as the first line of treatment against Alzheimer's disease (AD). The new generation of AChEIs, represented by Donepezil (1996), Galantamine (2001) and Rivastigmine (2002), is the only treatment for AD to date, together with Memantine (2003). AChEIs are not devoid of side-effects and their cost-effectiveness is limited. An option to optimize the correct use of AChEIs is the implementation of pharmacogenetics (PGx) in the clinical practice.

AREAS COVERED

(i) The cholinergic system in AD, (ii) principles of AD PGx, (iii) PGx of Donepezil, Galantamine, Rivastigmine, Huperzine and other treatments, and (iv) practical recommendations.

EXPERT OPINION

The most relevant genes influencing AChEI efficacy and safety are APOE and CYPs. APOE-4 carriers are the worst responders to AChEIs. With the exception of Rivastigmine (UGT2B7, BCHE-K), the other AChEIs are primarily metabolized via CYP2D6, CYP3A4, and UGT enzymes, with involvement of ABC transporters and cholinergic genes (CHAT, ACHE, BCHE, SLC5A7, SLC18A3, CHRNA7) in most ethnic groups. Defective variants may affect the clinical response to AChEIs. PGx geno-phenotyping is highly recommended prior to treatment.

Potassium channels in the neuronal homeostasis and neurodegenerative pathways underlying Alzheimer's disease: An update

With more than 80 subunits, potassium (K⁺) channels represent a group of ion channels showing high degree of diversity and ubiquity. They play important role in the control of membrane depolarization and cell excitability in several tissues, including the brain. Controlling the intracellular and extracellular K⁺ flow in cells, they also modulate the hormone and neurotransmitter release, apoptosis and cell proliferation. It is therefore not surprising that an improper functioning of K⁺ channels in neurons has been associated with pathophysiology of a wide range of neurological disorders, especially Alzheimer's disease (AD). This review aims to give a comprehensive overview of the basic properties and pathophysiological functions of the main classes of K⁺ channels in the context of disease processes, also discussing the progress, challenges and opportunities to develop drugs targeting these channels as potential pharmacological approach for AD treatment.

Cardiovascular safety of prokinetic agents: A focus on drug-induced arrhythmias

BACKGROUND

Gastrointestinal sensorimotor dysfunction underlies a wide range of esophageal, gastric, and intestinal motility and functional disorders that collectively constitute nearly half of all referrals to gastroenterologists. As a result, substantial effort has been dedicated toward the development of prokinetic agents intended to augment or restore normal gastrointestinal motility. However, the use of several clinically efficacious gastroprokinetic agents, such as cisapride, domperidone, erythromycin, and tegaserod, is associated with unfavorable cardiovascular safety profiles, leading to restrictions in their use.

PURPOSE

The purpose of this review is to detail the cellular and molecular mechanisms that lead commonly to drug-induced cardiac arrhythmias, specifically drug-induced long QT syndrome, torsades de pointes, and ventricular fibrillation, to examine the cardiovascular safety profiles of several classes of prokinetic agents currently in clinical use, and to explore potential strategies by which the risk of drug-induced cardiac arrhythmia associated with prokinetic agents and other QT interval prolonging medications can be mitigated successfully.

Inhibitory effects of cholinesterase inhibitor donepezil on the Kv1.5 potassium channel

Kv1.5 channels carry ultra-rapid delayed rectifier K⁺ currents in excitable cells, including neurons and cardiac myocytes. In the current study, the effects of cholinesterase inhibitor donepezil on cloned Kv1.5 channels expressed in HEK29 cells were explored using whole-cell recording technique. Exposure to donepezil resulted in a rapid and reversible block of Kv1.5 currents, with an IC₅₀ value of 72.5 μM. The mutant R476V significantly reduced the binding affinity of donepezil to Kv1.5 channels, showing the target site in the outer mouth region. Donepezil produced a significant delay in the duration of activation and deactivation, and mutant R476V potentiated these effects without altering activation curves. In response to slowed deactivation time course, a typical crossover of Kv1.5 tail currents was clearly evident after bath application of donepezil. In addition, both this chemical and mutant R476V accelerated current decay during channel inactivation in a voltage-dependent way, but barely changed the inactivation and recovery curves. The presence of donepezil exhibited the use-dependent block of Kv1.5 currents in response to a series of depolarizing pulses. Our data indicate that donepezil can directly block Kv1.5 channels in its open and closed states.

Pharmacological benefits of selective modulation of cannabinoid receptor type 2 (CB2) in experimental Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that pervasively affects the population across the world. Currently, there is no effective treatment available for this and existing drugs merely slow the progression of cognitive function decline. Thus, massive effort is required to find an intended therapeutic target to overcome this condition. The present study has been framed to investigate the ameliorative role of selective modulator of cannabinoid receptor type 2 (CB2), 1-phenylisatin in experimental AD condition. We have induced experimental AD in mice by using two induction models viz., intracerebroventricular (i.c.v.) administration of streptozotocin (STZ) and aluminum trichloride (AlCl3)+d-galactose. Morris water maze (MWM) and attentional set shifting test (ASST) were used to assess learning and memory. Hematoxylin-eosin and Congo red staining were used to examine the structural variation in brain. Brain oxidative stress (thiobarbituric acid reactive substance and glutathione), nitric oxide levels (nitrites/nitrates), acetyl cholinesterase activity, myeloperoxidase and calcium levels were also estimated. i.c.v. STZ as well as AlCl3+d-galactose have impaired spatial and reversal learning with executive functioning, increased brain oxidative and nitrosative stress, cholinergic activity, inflammation and calcium levels. Furthermore, these agents have also enhanced the burden of Aβ plaque in the brain. Treatment with 1-phenylisatin and donepezil attenuated i.c.v. STZ as well as AlCl3+d-galactose induced impairment of learning-memory, brain biochemistry and brain damage. Hence, this study concludes that CB2 receptor modulation can be a potential therapeutic target for the management of AD.