Donepezil-induced torsades de pointes without QT prolongation

Adverse Drug Reactions of Acetylcholinesterase Inhibitors in Older People Living with Dementia: A Comprehensive Literature Review

The rising of global geriatric population has contributed to increased prevalence of dementia. Dementia is a neurodegenerative disease, which is characterized by progressive deterioration of cognitive functions, such as judgment, language, memory, attention and visuospatial ability. Dementia not only has profoundly devastating physical and psychological health outcomes, but it also poses a considerable healthcare expenditure and burdens. Acetylcholinesterase inhibitors (AChEIs), or so-called anti-dementia medications, have been developed to delay the progression of neurocognitive disorders and to decrease healthcare needs. AChEIs have been widely prescribed in clinical practice for the treatment of Alzheimer's disease, which account for 70% of dementia. The rising use of AChEIs results in increased adverse drug reactions (ADRs) such as cardiovascular and gastrointestinal adverse effects, resulting from overstimulation of peripheral cholinergic activity and muscarinic receptor activation. Changes in pharmacokinetics (PK), pharmacodynamics (PD) and pharmacogenetics (PGx), and occurrence of drug interactions are said to be major risk factors of ADRs of AChEIs in this population. To date, comprehensive reviews in ADRs of AChEIs have so far been scarcely studied. Therefore, we aimed to recapitulate and update the diverse aspects of AChEIs, including the mechanisms of action, characteristics and risk factors of ADRs, and preventive strategies of their ADRs. The collation of this knowledge is essential to facilitate efforts to reduce ADRs of AChEIs.

Effect of Memantine on QT/QTc Interval in a Healthy Korean Population

Studies on the effects of memantine on QT prolongation have yielded conflicting results. For a long time, memantine was reported to be a safe drug without QT prolongation; however, several case studies have reported memantine-induced QT prolongation in Alzheimer's patients. This study evaluated the relationship between memantine blood levels, and QT interval changes. Over a 2-week period, we orally administered 20 mg of memantine daily to achieve a steady state in 57 healthy Korean subjects. We measured and analyzed the QT interval and blood memantine concentrations simultaneously before and after treatment, as well as 2 weeks after the last dosing. Correlation analysis was done between blood memantine level and QT interval. No serious adverse events occurred during the study period. Repeated dosing of memantine did not show clinically significant QT interval changes after treatment. Regression analysis was performed based on the results; there was no statistical association between memantine blood level and QT prolongation. In conclusion, the results of the present study demonstrated no clinically significant changes in the QT interval with therapeutic blood levels of memantine.

Effect of QT Prolongation in Patients Taking Cholinesterase Inhibitors (Donepezil) for Alzheimer's Disease

Background: Cholinesterase inhibitors such as donepezil are used in the treatment of Alzheimer’s disease. Patients taking cholinesterase inhibitors can develop cholinergically mediated QT prolongation, which may lead to life-threatening arrhythmias. In this study we investigated the corrected QT interval (QTc) of patients taking donepezil.

Methods and Results: This study enrolled 114 outpatients attending Tarumizu Chuo Hospital. Subjects were divided into a donepezil group (n=57) or an age- and sex-matched control group (n=57). Physical findings, laboratory data, and electrocardiographic parameters were compared between the groups. QTc was significantly prolonged (mean [±SD] 0.443±0.032 s vs. 0.426±0.026s; P<0.001) and the percentage of patients with prolonged QTc was significantly higher (30% vs. 9%; P<0.01) in the donepezil than control group. Furthermore, in the donepezil group, QTc was significantly prolonged after patients started taking donepezil compared with baseline (from 0.433±0.034 to 0.442±0.033s; n=46; P<0.05). On univariate analysis, QTc was significantly associated with taking donepezil, as well as with hemoglobin, serum calcium concentration, and estimated glomerular filtration rate (eGFR; all P<0.01). On multivariate analysis, QTc was significantly associated with taking donepezil (P<0.001), serum potassium concentration (P<0.05), and eGFR (P<0.05).

Conclusions: The incidence of QTc prolongation was more frequent in patients taking donepezil than in the control group, and was difficult to predict. Periodic electrocardiogram examinations are recommended considering the possibility of adverse events, such as fatal arrhythmias.

QTc Interval Prolongation with Therapies Used to Treat Patients with Parkinson's Disease Psychosis: A Narrative Review

In addition to the classic motor symptoms of Parkinson's disease (PD), people with PD frequently experience nonmotor symptoms that can include autonomic dysfunction and neuropsychiatric symptoms such as PD psychosis (PDP). Common patient characteristics, including older age, use of multiple medications, and arrhythmias, are associated with increased risk of corrected QT interval (QTc) prolongation, and treatments for PDP (antipsychotics, dementia medications) may further increase this risk. This review evaluates how medications used to treat PDP affect QTc interval from literature indexed in the PubMed and Embase databases. Although not indicated for the treatment of psychosis, dementia therapies such as donepezil, rivastigmine, memantine, and galantamine are often used with or without antipsychotics and have minimal effects on QTc interval. Among the antipsychotics, data suggesting clinically meaningful QTc interval prolongation are limited. However, many antipsychotics have other safety concerns. Aripiprazole, olanzapine, and risperidone negatively affect motor function and are not recommended for PDP. Quetiapine is often sedating, can exacerbate underlying neurogenic orthostatic hypotension, and may prolong the QTc interval. Pimavanserin was approved by the US Food and Drug Administration (FDA) in 2016 and remains the only FDA-approved medication available to treat hallucinations and delusions associated with PDP. However, pimavanserin can increase QTc interval by approximately 5-8 ms. The potential for QTc prolongation should be considered in patients with symptomatic cardiac arrhythmias and those receiving QT-prolonging medications. In choosing a medication to treat PDP, expected efficacy must be balanced with potential safety concerns for individual patients.

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.

Correlation Between Donepezil and QTc Prolongation and Torsades de Pointes: A Very Rare Phenomenon

Dementia can be seen as a clinical syndrome featuring a decline in cognitive and psychological abilities that can cause disability. Two major kinds of drugs are available: N-methyl-D-aspartic acid receptor antagonists like memantine and acetylcholinesterase inhibitors such as galantamine, rivastigmine and donepezil. In this article, we have reviewed the available literature along with the provision of a snapshot of published cases in the literature We used the PubMed database for our search. The average age of patients was 80 years and above. Patients described in the literature belonged to both female and male gender, with female patients being predominant. Patients demonstrated associated atrioventricular (AV) block or ventricular premature contractions (VPC) or atrial fibrillation (AF) prior to developing torsades de pointes (TdP). Presenting complaints were either syncope or diarrhoea or accidental bradycardia. Mostly, the corrected QT interval (QTc) normalisation was associated with discontinuation of donepezil. We recommend further studies to determine this correlation between donepezil and incidence of QTc prolongation and TdP.

A case of donepezil-related torsades de pointes

An 80-year-old woman with Alzheimer's dementia presented with diarrhoea, vomiting and worsening confusion following an increase in donepezil dose from 5 to 10 mg. The ECG revealed prolongation of QTc interval. Soon after admission, she became unresponsive with polymorphic ventricular tachycardia (VT). Cardiopulmonary resuscitation with a 200 J shock was successful in establishing cardiac output. Following the discontinuation of donepezil, the QTc interval normalised and no further arrhythmias were recorded. Treatment with anticholinesterase inhibitors may result in life-threatening VT. Vigilance is required for the identification of this condition in patients presenting with presyncope, syncope or seizures.