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BMJ Open Sep 2018Spinal and bulbar muscular atrophy (SBMA) is a slowly progressive neuromuscular disease. Cold exposure often leads to worsening of motor symptoms including paresis....
Study protocol for the MEXiletine hydrochloride administration trial: a placebo-controlled, randomised, double-blind, multicentre, crossover study of its efficacy and safety in spinal and bulbar muscular atrophy (MEXPRESS).
INTRODUCTION
Spinal and bulbar muscular atrophy (SBMA) is a slowly progressive neuromuscular disease. Cold exposure often leads to worsening of motor symptoms including paresis. Although mexiletine hydrochloride administration has been shown to be effective for the treatment of several muscular diseases, its effectiveness in SBMA has not been validated to date. The trial will test it as a symptomatic drug for cold paresis. This study is the first trial to evaluate the efficacy and safety of mexiletine hydrochloride administration in patients with SBMA.
METHODS AND ANALYSIS
A placebo-controlled, randomised, double-blind, multicentre, crossover clinical trial will be conducted to assess the safety and efficacy of mexiletine hydrochloride in patients with SBMA. The eligible patients will be assigned randomly in a 1:1 ratio to two groups in a double-blind manner. Participants will take mexiletine hydrochloride (300 mg/day) or a placebo orally three times a day for 4 weeks (period 1). After a 1-week washout period, participants will take the other drug for 4 weeks (period 2). The primary endpoint is the difference in distal latencies between room temperature and cold exposure conditions.
ETHICS AND DISSEMINATION
This study will be conducted in compliance with the Helsinki Declaration and the Ethical Guidelines for Medical and Health Research Involving Human Subjects by the Japanese government and has been approved by the ethics committee of Nagoya University Graduate School of Medicine, as a central institutional review board, and by each facility. The results will be disseminated in peer-reviewed journals and at scientific conferences.
TRIAL REGISTRATION NUMBER
UMIN000026150; Pre-results.
Topics: Adult; Aged; Aged, 80 and over; Humans; Male; Middle Aged; Activities of Daily Living; Bulbo-Spinal Atrophy, X-Linked; Cold Temperature; Cross-Over Studies; Double-Blind Method; Drug Monitoring; Japan; Mexiletine; Neurologic Examination; Paresis; Treatment Outcome; Voltage-Gated Sodium Channel Blockers; Multicenter Studies as Topic; Randomized Controlled Trials as Topic
PubMed: 30206090
DOI: 10.1136/bmjopen-2018-023041 -
Neurology. Clinical Practice Oct 2021Myotonic dystrophy types 1 and 2 are progressive multisystem genetic disorders whose core clinical feature is myotonia. Mexiletine, an antagonist of voltage-gated sodium...
BACKGROUND AND OBJECTIVE
Myotonic dystrophy types 1 and 2 are progressive multisystem genetic disorders whose core clinical feature is myotonia. Mexiletine, an antagonist of voltage-gated sodium channels, is a recommended antimyotonic agent in the nondystrophic myotonias, but its use in myotonic dystrophy is limited because of lack of data regarding its long-term efficacy and safety profile.
METHODS
To address this issue, this study retrospectively evaluated patients with myotonic dystrophy receiving mexiletine over a mean time period of 32.9 months (range 0.1-216 months).
RESULTS
This study demonstrated that 96% of patients reported some improvement in myotonia symptoms with mexiletine treatment. No clinically relevant cardiac adverse events were associated with the long-term use of mexiletine.
CONCLUSIONS
These findings support that mexiletine is both safe and effective when used long-term in myotonic dystrophy.
CLASSIFICATION OF EVIDENCE
This study provides Class IV evidence that mexiletine is a well-tolerated and effective treatment for myotonic dystrophy types 1 and 2.
PubMed: 34840883
DOI: 10.1212/CPJ.0000000000001073 -
Frontiers in Pharmacology 2023This study aimed to identify the different associations between antiarrhythmic drugs (AADs) and arrhythmias, and to determine whether pharmacokinetic drug interactions...
This study aimed to identify the different associations between antiarrhythmic drugs (AADs) and arrhythmias, and to determine whether pharmacokinetic drug interactions involving AADs increase the risk of AAD-related arrhythmias compared to using AADs alone. The disproportionality analysis of AAD-associated cardiac arrhythmias, including AAD monotherapies and concomitant use of pharmacokinetic interacting agents involving AADs, was conducted by using reporting odds ratio (ROR) and information component (IC) as detection of potential safety signals based on FAERS data from January 2016 to June 2022. We compared the clinical features of patients reported with AAD-associated arrhythmias between fatal and non-fatal groups, and further investigated the onset time (TTO) following different AAD regimens. A total of 11754 AAD-associated cardiac arrhythmias reports were identified, which was more likely to occur in the elderly (52.17%). Significant signals were detected between cardiac arrhythmia and all AAD monotherapies, with ROR ranging from 4.86 with mexiletine to 11.07 with flecainide. Regarding four specific arrhythmias in High Level Term (HLT) level, the AAD monotherapies with the highest ROR were flecainide in cardiac conduction disorders (ROR025 = 21.18), propafenone in rate and rhythm disorders (ROR025 = 10.36), dofetilide in supraventricular arrhythmias (ROR025 = 17.61), and ibutilide in ventricular arrhythmias (ROR025 = 4.91). Dofetilide/ibutilide, ibutilide, mexiletine/ibutilide and dronedarone presented no signal in the above four specific arrhythmias respectively. Compared with amiodarone monotherapy, sofosbuvir plus amiodarone detected the most significantly increased ROR in arrhythmias. The investigation showed the spectrum and risk of AAD-associated cardiac arrhythmias varied among different AAD therapies. The early identification and management of AAD-associated arrhythmias are of great importance in clinical practice.
PubMed: 37251345
DOI: 10.3389/fphar.2023.1170039 -
European Journal of Hospital Pharmacy :... Nov 2016Myotonia is found in a number of muscle diseases, including myotonic dystrophy and non-dystrophic myotonia. The resulting symptoms of myotonia can interfere with daily... (Review)
Review
INTRODUCTION
Myotonia is found in a number of muscle diseases, including myotonic dystrophy and non-dystrophic myotonia. The resulting symptoms of myotonia can interfere with daily activities such as walking or climbing the stairs. Due to the rarity of both these conditions, pharmacological treatment of myotonia is largely anecdotal and is led by specialist clinicians who tend to favour the use of mexiletine, a class 1b antiarrhythmic sodium antagonist.
OBJECTIVE
To identify and review randomised controlled trials in order to assess the efficacy and safety of use of mexiletine in myotonic dystrophy and non-dystrophic myotonia for two different patient cases.
SEARCH METHODS
The literature search was conducted using MEDLINE, EMBASE and The Cochrane Library (from January 1990 to December 2014). Specialist neurology centres were also contacted.
SELECTION CRITERIA
All randomised controlled trials between January 1990 and December 2014 which compared the use of mexiletine for the treatment of myotonia in patients who suffer from myotonic dystrophy and non-dystrophic were included in this review. Primary outcome: reduction of clinical myotonia.
RESULTS
Two randomised controlled trials were included for review. Both studies are underpowered; however, there is evidence to support the use of mexiletine for the improvement of clinical myotonia.
CONCLUSIONS
Larger randomised controlled trials are required, which look at the functional effect of myotonia as a primary outcome (ie, stair test) and the long-term use of mexiletine. This is needed to establish the ongoing efficacy and safety of the long-term use of mexiletine in the management of myotonia.
PubMed: 31156883
DOI: 10.1136/ejhpharm-2015-000839 -
Europace : European Pacing,... Nov 2022While mexiletine has been used for over 40 years for prevention of (recurrent) ventricular arrhythmias and for myotonia, patient access has recently been critically...
AIMS
While mexiletine has been used for over 40 years for prevention of (recurrent) ventricular arrhythmias and for myotonia, patient access has recently been critically endangered. Here we aim to demonstrate the effectiveness and safety of mexiletine in the treatment of patients with (recurrent) ventricular arrhythmias, emphasizing the absolute necessity of its accessibility.
METHODS AND RESULTS
Studies were included in this systematic review (PROSPERO, CRD42020213434) if the efficacy or safety of mexiletine in any dose was evaluated in patients at risk for (recurrent) ventricular arrhythmias with or without comparison with alternative treatments (e.g. placebo). A systematic search was performed in Ovid MEDLINE, Embase, and in the clinical trial registry databases ClinicalTrials.gov and ICTRP. Risk of bias were assessed and tailored to the different study designs. Large heterogeneity in study designs and outcome measures prompted a narrative synthesis approach. In total, 221 studies were included reporting on 8970 patients treated with mexiletine. Age ranged from 0 to 88 years. A decrease in ventricular arrhythmias of >50% was observed in 72% of the studies for pre-mature ventricular complexes, 64% for ventricular tachycardia, and 33% for ventricular fibrillation. Electrocardiographic effects of mexiletine were small; only in a subset of patients with primary arrhythmia syndromes, a relative (desired) QTc decrease was reproducibly observed. As for adverse events, gastrointestinal complaints were most frequently observed (33% of the patients).
CONCLUSIONS
In this systematic review, we present all the currently available knowledge of mexiletine in patients at risk for (recurrent) ventricular arrhythmias and show that mexiletine is both effective and safe.
Topics: Humans; Infant, Newborn; Infant; Child, Preschool; Child; Adolescent; Young Adult; Adult; Middle Aged; Aged; Aged, 80 and over; Mexiletine; Arrhythmias, Cardiac; Ventricular Fibrillation; Electrocardiography; Heart Ventricles
PubMed: 36036670
DOI: 10.1093/europace/euac087 -
Pharmacology Research & Perspectives Aug 2021Prolongation of the cardiac action potential (AP) and early after depolarizations (EADs) are electrical anomalies of cardiomyocytes that can lead to lethal arrhythmias...
Prolongation of the cardiac action potential (AP) and early after depolarizations (EADs) are electrical anomalies of cardiomyocytes that can lead to lethal arrhythmias and are potential liabilities for existing drugs and drug candidates in development. For example, long QT syndrome-3 (LQTS3) is caused by mutations in the Na 1.5 sodium channel that debilitate channel inactivation and cause arrhythmias. We tested the hypothesis that a useful drug (i.e., mexiletine) with potential liabilities (i.e., potassium channel inhibition and adverse reactions) could be re-engineered by dynamic medicinal chemistry to afford a new drug candidate with greater efficacy and less toxicity. Human cardiomyocytes were generated from LQTS3 patient-derived induced pluripotent stem cells (hIPSCs) and normal hIPSCs to determine beneficial (on-target) and detrimental effects (off-target) of mexiletine and synthetic analogs, respectively. The approach combined "drug discovery" and "hit to lead" refinement and showed that iterations of medicinal chemistry and physiological testing afforded optimized compound 22. Compared to mexiletine, compound 22 showed a 1.85-fold greater AUC and no detectable CNS toxicity at 100 mg/kg. In vitro hepatic metabolism studies showed that 22 was metabolized via cytochrome P-450, as previously shown, and by the flavin-containing monooxygenase (FMO). Deuterated-22 showed decreased metabolism and showed acceptable cardiovascular and physicochemical properties.
Topics: Animals; Behavior, Animal; Cells, Cultured; Female; Humans; Induced Pluripotent Stem Cells; Liver; Long QT Syndrome; Male; Mexiletine; Mice, Inbred BALB C; Myocytes, Cardiac; Rats, Sprague-Dawley; Seizures; Mice; Rats
PubMed: 34327875
DOI: 10.1002/prp2.828 -
Palliative Medicine Dec 2017Rectal tenesmus is a distressing symptom in patients with advanced cancer and challenging to treat. There is lack of consensus on the appropriate management of tenesmus... (Review)
Review
BACKGROUND
Rectal tenesmus is a distressing symptom in patients with advanced cancer and challenging to treat. There is lack of consensus on the appropriate management of tenesmus in this patient population.
AIM
To identify and examine the effectiveness of interventions to palliate rectal tenesmus caused by advanced cancer when surgery, radiotherapy or chemotherapy are no longer treatment options.
DESIGN
A systematic review of the literature following standard systematic review methodology and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidance.
DATA SOURCES
A comprehensive search of the electronic databases MEDLINE, EMBASE and the Cochrane Library was conducted from date of inception to April 2016. PubMed 'related articles' search, grey literature search and hand-searches of the bibliographies of relevant papers and textbooks were also performed. Non-cancer patients were excluded. Any studies involving surgery or radiotherapy to treat tenesmus were excluded. Studies involving interventions to treat pelvic pain syndromes without specific outcome measures on severity of tenesmus were excluded. The quality of the studies was assessed using a National Institute for Health and Clinical Excellence-recommended quality assessment tool.
RESULTS
From 861 studies, 9 met full criteria and were selected. All were case series investigating the use of pharmacological interventions (diltiazem, nifedipine, methadone, mexiletine hydrochloride, lidocaine and bupivacaine), anaesthetic interventions (lumbar sympathectomy, neurolytic superior hypogastric plexus block), and endoscopic laser interventions. The included studies showed substantial heterogeneity, and therefore, a meta-analysis was not feasible.
CONCLUSION
From this review, we identified a significant gap in research into the palliation of rectal tenesmus. A multimodal approach may be necessary due to the complexity of the pathophysiology of tenesmus. Future research should focus on randomised controlled trials of drug therapies whose potential effectiveness is suggested by case series.
Topics: Anesthesia; Anesthetics; Calcium Channel Blockers; Humans; Laser Therapy; Neoplasms; Palliative Care; Rectal Diseases
PubMed: 28590211
DOI: 10.1177/0269216317697897 -
Frontiers in Neurology 2022Non-dystrophic myotonias (NDMs) are skeletal muscle ion channelopathies caused by or mutations. This study aimed to describe the clinical, myopathological, and genetic...
INTRODUCTION
Non-dystrophic myotonias (NDMs) are skeletal muscle ion channelopathies caused by or mutations. This study aimed to describe the clinical, myopathological, and genetic analysis of NDM in a large Chinese cohort.
METHODS
We reviewed the clinical manifestations, laboratory results, electrocardiogram, electromyography, muscle biopsy, genetic analysis, treatment, and follow-up of 20 patients (from 18 families) with NDM.
RESULTS
Cases included myotonia congenita (MC, 17/20) and paramyotonia congenita (PMC, 3/20). Muscle stiffness and hypertrophy, grip and percussion myotonia, and the warm-up phenomenon were frequently observed in MC and PMC patients. Facial stiffness, eye closure myotonia, and cold sensitivity were more common in PMC patients and could be accompanied by permanent weakness. Nine MC patients and two PMC patients had cardiac abnormalities, mainly manifested as cardiac arrhythmia, and the father of one patient died of sudden cardiac arrest. Myotonic runs in electromyography were found in all patients, and seven MC patients had mild myopathic changes. There was no difference in muscle pathology between MC and PMC patients, most of whom had abnormal muscle fiber type distribution or selective muscle fiber atrophy. Nineteen variants were found in 17 MC patients, among which c.795T>G (p.D265E) was a new variant, and two variants were found in three PMC patients. The patients were treated with mexiletine and/or carbamazepine, and the symptoms of myotonia were partially improved.
CONCLUSIONS
MC and PMC have considerable phenotypic overlap. Genetic investigation contributes to identifying the subtype of NDM. The muscle pathology of NDM lacks specific changes.
PubMed: 35350395
DOI: 10.3389/fneur.2022.830707 -
Clinical Pharmacology and Therapeutics Nov 2022Selective voltage-gated sodium channel blockers are of growing interest as treatment for pain. For drug development of such compounds, it would be critical to have a... (Randomized Controlled Trial)
Randomized Controlled Trial
Selective voltage-gated sodium channel blockers are of growing interest as treatment for pain. For drug development of such compounds, it would be critical to have a biomarker that can be used for proof-of-mechanism. We aimed to evaluate whether drug-induced changes in sodium conductance can be detected in the peripheral nerve excitability profile in 18 healthy subjects. In a randomized, double-blind, 3-way crossover study, effects of single oral doses of 333 mg mexiletine and 300 mg lacosamide were compared with placebo. On each study visit, motor and sensory nerve excitability measurements of the median nerve were performed (predose; and 3 and 6 hours postdose) using Qtrac. Treatment effects were calculated using an analysis of covariance (ANCOVA) with baseline as covariate. Mexiletine and lacosamide had significant effects on multiple motor and sensory nerve excitability variables. Depolarizing threshold electrotonus (TEd (40-60 ms)) decreased by mexiletine (estimated difference (ED) -1.37% (95% confidence interval (CI): -2.20, -0.547; P = 0.002) and lacosamide (ED -1.27%, 95% CI: -2.10, -0.443; P = 0.004) in motor nerves. Moreover, mexiletine and lacosamide decreased superexcitability (less negative) in motor nerves (ED 1.74%, 95% CI: 0.615, 2.87; P = 0.004, and ED 1.47%, 95% CI: 0.341, 2.60; P = 0.013, respectively). Strength-duration time constant decreased after lacosamide in motor- (ED -0.0342 ms, 95% CI: -0.0571, -0.0112; P = 0.005) and sensory nerves (ED -0.0778 ms, 95% CI: -0.116, -0.0399; P < 0.001). Mexiletine and lacosamide significantly decrease excitability of motor and sensory nerves, in line with their suggested mechanism of action. Results of this study indicate that nerve excitability threshold tracking can be an effective pharmacodynamic biomarker. The method could be a valuable tool in clinical drug development.
Topics: Humans; Lacosamide; Mexiletine; Cross-Over Studies; Voltage-Gated Sodium Channel Blockers; Healthy Volunteers; Double-Blind Method; Sodium
PubMed: 35762293
DOI: 10.1002/cpt.2694 -
Biological & Pharmaceutical Bulletin 2022Evaluation of drug-induced cardiotoxicity is still challenging to avoid adverse effects, such as torsade de pointes (TdP), in non-clinical and clinical studies. Numerous...
Evaluation of drug-induced cardiotoxicity is still challenging to avoid adverse effects, such as torsade de pointes (TdP), in non-clinical and clinical studies. Numerous studies have suggested that human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are a useful platform for detecting drug-induced TdP risks. Comprehensive in vitro Proarrhythmia Assay (CiPA) validation study suggested that hiPSC-CMs can assess clinical TdP risk more accurately than the human ether-a-go-go-related assay and QT interval prolongation. However, there were still some outliers, such as bepridil, mexiletine, and ranolazine, among the CiPA 28 compounds in the CiPA international multi-site study using hiPSC-CMs. In this study, we assessed the effects of the positive compound dofetilide, the negative compound aspirin, and several CiPA compounds (bepridil, mexiletine, and ranolazine) on the electromechanical window (E-M window), which were evaluated using multi-electrode array assay and motion analysis, in hiPSC-CMs. Similar to previous in vivo studies, dofetilide, which has a high TdP risk, decreased the E-M window in hiPSC-CMs, whereas aspirin, which has a low TdP risk, had little effect. Bepridil, classified in the high TdP-risk group in CiPA, decreased the E-M window in hiPSC-CMs, whereas ranolazine and mexiletine, which are classified in the low TdP-risk group in CiPA, slightly decreased or had little effect on the E-M window of hiPSC-CMs. Thus, the E-M window in hiPSC-CMs can be used to classify drugs into high and low TdP risk.
Topics: Aspirin; Bepridil; DNA-Binding Proteins; Humans; Induced Pluripotent Stem Cells; Mexiletine; Myocytes, Cardiac; Ranolazine; Risk Assessment
PubMed: 35786601
DOI: 10.1248/bpb.b22-00268