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Heart Rhythm Nov 2020Myotonic dystrophy type 1 (DM1) is a multisystemic disorder characterized by progressive cardiac conduction impairment, arrhythmias, and sudden death. Mexiletine is a...
BACKGROUND
Myotonic dystrophy type 1 (DM1) is a multisystemic disorder characterized by progressive cardiac conduction impairment, arrhythmias, and sudden death. Mexiletine is a sodium channel blocker drug used by patients with DM1 for treatment of myotonia, even though definitive proof of its safety over long-term follow-up is lacking.
OBJECTIVE
The purpose of this study was to assess the impact of mexiletine for treatment of neurological symptoms on the composite endpoint of significant electrocardiogram modification (new onset or worsening of atrioventricular [AV] or intraventricular conduction delay) and bradyarrhythmic complications requiring pacemaker (PM) implantation (advanced AV block, symptomatic sinus pause >3 seconds).
METHODS
This retrospective longitudinal study included a series of consecutive patients with genetically confirmed DM1 evaluated at our neurology and cardiology clinics from January 1, 2011, to January 1, 2020, who received mexiletine 200 mg twice daily. Patients with a PM, implantable cardioverter-defibrillator, or severe conduction abnormality (PQ interval ≥230 ms, complete bundle branch block, or atrial fibrillation) at enrollment were excluded.
RESULTS
The study comprised 18 mexiletine-treated patients and 68 mexiletine-free controls. Over median follow-up of 53 months, the endpoint was reached by 4 (22%) mexiletine-treated patients and 23 (33%) non-mexiletine-treated patients (log-rank P = .45). In 3 non-mexiletine-treated patients, bradyarrhythmic complications requiring PM implantation were observed. At univariable analysis, only the presence of mild conduction delay (first-degree AV block with PQ interval <230 ms or left anterior fascicular block) at baseline predicted the endpoint (hazard ratio 2.22; 95% confidence interval 1.04-4.76).
CONCLUSION
Mexiletine 200 mg twice daily is safe in patients with DM1 and no severe conduction abnormality.
Topics: Adult; Atrioventricular Block; Cardiac Pacing, Artificial; Defibrillators, Implantable; Electrocardiography; Female; Follow-Up Studies; Humans; Male; Middle Aged; Myotonic Dystrophy; Prognosis; Retrospective Studies; Time Factors
PubMed: 32525073
DOI: 10.1016/j.hrthm.2020.05.043 -
International Journal of... 2021As adrenaline, serotonin and norepinephrine are two other vasoconstrictors and both of which have been proved to increase the quality and duration of local anesthetics... (Comparative Study)
Comparative Study
As adrenaline, serotonin and norepinephrine are two other vasoconstrictors and both of which have been proved to increase the quality and duration of local anesthetics when added as adjuvants. However, the difference in the improvement of the nociception of local anesthetics between the two adjuvants remains unclear. The purpose of this study was to assess the cutaneous nociception of mexiletine by coadministration with serotonin and norepinephrine. Subcutaneous injection of drugs or combinations includes mexiletine 0.6, 1.8, 6.0 μmol, serotonin 1.6500 μmol, noradrenaline 0.8895 nmol, saline, mexiletine 1.8 and 6.0 μmol, respectively combined with serotonin 0.4125, 0.8250, 1.6500 μmol and noradrenaline 0.0356, 0.1779, 0.8895 nmol, with each injection dose of 0.6 ml. The nociception of mexiletine alone and mexiletine coadministered with serotonin and norepinephrine was assessed after subcutaneous injection. Subcutaneous injections of mexiletine elicited dose-related cutaneous antinociception ( < 0.05, 0.01, or 0.001). Compared with mexiletine (1.8 μmol), adding norepinephrine (except for lowest dose) and serotonin to mexiletine (1.8 μmol) solutions for skin nociceptive block potentiated and prolonged the action ( < 0.01 or 0.001). Mexiletine (6.0 μmol) combined with norepinephrine and serotonin extended the duration of cutaneous antinociception when compared with mexiletine (6.0 μmol) alone ( < 0.05, 0.01, or 0.001). Both serotonin and norepinephrine improve the sensory block and enhances the nociceptive block duration of mexiletine, and serotonin is superior to that of norepinephrine.
Topics: Analgesics; Anesthetics, Local; Animals; Dose-Response Relationship, Drug; Drug Combinations; Male; Mexiletine; Norepinephrine; Pain; Rats, Sprague-Dawley; Serotonin; Skin; Rats
PubMed: 33998312
DOI: 10.1177/20587384211016129 -
Europace : European Pacing,... Oct 2022The aim of the study was to systematically review evidence on the effectiveness and safety of oral mexiletine administered in monotherapy or in combination with other...
The aim of the study was to systematically review evidence on the effectiveness and safety of oral mexiletine administered in monotherapy or in combination with other antiarrhythmic drugs for recurrent ventricular arrhythmia (ventricular tachycardia/ventricular fibrillation, VT/VF) in adult patients with structural heart disease (SHD) and implantable cardioverter defibrillators (ICDs). We systematically searched MEDLINE, Embase, and CENTRAL databases from inception to 27 August 2021 for prospective and retrospective studies investigating mexiletine in the target population. The main outcome was the reduction of ICD therapy. The main safety outcome was the presence of any serious adverse events (SAEs) leading to mexiletine discontinuation. Study quality was assessed using the Cochrane risk of bias tool or the Newcastle-Ottawa scale. Four studies comprising 86 mexiletine recipients were included in the review. We also obtained individual data of 50 patients from two studies. Ischaemic cardiomyopathy (ICM) was present in 86% of patients. The quality of included studies was moderate/low. A narrative review was undertaken as studies varied widely in terms of study population and treatment. Across studies, mexiletine treatment (with or without amiodarone) seemed to consistently reduce the number of ICD therapies especially in a population where catheter ablation (CA) was unsuccessful or contraindicated. In ICM patients deemed eligible for CA, mexiletine seemed to be inferior to CA. Mexiletine was discontinued in 14% of cases, mainly for gastrointestinal or neurological SAE. Mexiletine seems to be an option for the long-term treatment of recurrent VT/VF in adult patients with SHD, especially ICM, and ICD in whom CA was unsuccessful or not suitable.
Topics: Adult; Amiodarone; Anti-Arrhythmia Agents; Catheter Ablation; Defibrillators, Implantable; Humans; Mexiletine; Prospective Studies; Retrospective Studies; Tachycardia, Ventricular; Treatment Outcome; Ventricular Fibrillation
PubMed: 35851797
DOI: 10.1093/europace/euac101 -
La Revue de Medecine Interne Oct 2022Paroxysmal vascular acrosyndromes are related to a peripheral vasomotor disorder and presented as paroxysmal color changes of the fingers. They include primary Raynaud's...
Paroxysmal vascular acrosyndromes are related to a peripheral vasomotor disorder and presented as paroxysmal color changes of the fingers. They include primary Raynaud's phenomenon (RP), which is the most common, secondary RP and erythermalgia. They are to be distinguished from non-paroxysmal acrosyndromes such as acrocyanosis and chilblains, which are very frequent and often associated with RP, digital ischemia and necrosis, spontaneous digital hematoma and acrocholosis. The challenge of a consultation for a vascular acrosyndrome is to make positive diagnosis through history and clinical examination, and to specify its nature, to prescribe complementary exams. In any patient consulting for RP, assessment includes at least an antinuclear antibody test and capillaroscopy. For erythermalgia, a blood count and even a search for JAK2 mutation are required. A thryoid-stimulating hormon assay, a test for antinuclear antibodies, and a search for small fiber neuropathy are also performed. The treatment of RP is essentially documented for secondary RP where calcium channel blockers are indicated in first line, and iloprost in severe cases. The treatment of primitive erythermalgia is based on sodium channel blockers such as mexiletine or lidocaine infusions, and on drugs effective on neuropathic pain, such as gabapentin or amitryptiline, in case of erythermalgia associated with small fiber neuropathy. The treatment of erythermalgia associated with myeloproliferative syndromes is based on etiological treatment and aspirin.
Topics: Antibodies, Antinuclear; Aspirin; Calcium Channel Blockers; Erythromelalgia; Gabapentin; Humans; Iloprost; Lidocaine; Mexiletine; Raynaud Disease; Small Fiber Neuropathy; Sodium Channel Blockers
PubMed: 35835622
DOI: 10.1016/j.revmed.2022.03.338 -
Journal of Cardiac Failure Oct 2019To evaluate possible treatment-related hemodynamic changes, we administered ranolazine or mexiletine to swine with heart failure (HF) and to controls.
OBJECTIVES
To evaluate possible treatment-related hemodynamic changes, we administered ranolazine or mexiletine to swine with heart failure (HF) and to controls.
BACKGROUND
Ranolazine and mexiletine potently inhibit depolarizing late Na current (I) and Na entry into cardiomyocytes Blocking Na entry may increase forward-mode Na/Ca exchange and reduce cellular Ca load, further compromising systolic contraction during HF.
METHODS AND RESULTS
Anesthetized tachypaced HF swine received ranolazine (n = 9) or mexiletine (n = 7) as boluses, then as infusions; the same experiments were performed in 10 nonpaced controls. The swine with HF had characteristic elevated left ventricular end-diastolic pressure (LVEDP) and reduced maximal left ventricular pressure rise (+dP/dt) and left ventricular peak systolic pressure (LVSP). No significant change occurred after ranolazine dosing for any parameter: LVEDP, +dP/dt, LVSP, heart rate, maximal LV pressure fall rate (-dP/dt), or time constant for isovolumic relaxation. Similar results seen in additional swine with HF: 7 were given mexiletine, and 7 others were given ranolazine after a 27% rate decrement to maximize I. Patch-clamped HF cardiomyocytes confirmed drug-induced I blockade.
CONCLUSIONS
Ranolazine or mexiletine blocking I neither worsened nor improved hemodynamics during advanced HF. Although results must be clinically confirmed, they suggest inhibition of I by ranolazine or mexiletine may not exacerbate HF in patients.
Topics: Animals; Cardiovascular Agents; Disease Models, Animal; Disease Progression; Dose-Response Relationship, Drug; Drug Monitoring; Heart Failure; Hemodynamics; Mexiletine; Myocardial Contraction; Ranolazine; Swine; Voltage-Gated Sodium Channel Blockers; Voltage-Gated Sodium Channels
PubMed: 31461671
DOI: 10.1016/j.cardfail.2019.08.015 -
Cureus May 2020Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder involving abnormal motility. The patients are commonly started on symptom control management for...
Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder involving abnormal motility. The patients are commonly started on symptom control management for IBS - diarrhea subtype by prescribing antimotility agents, usually having opioid agonist activity, and newer medications have been emerging for this as well. Patients sometimes self-medicate themselves to exceedingly high doses of these medications to achieve symptoms control. There are only a few cases of opioid-induced arrhythmia in the literature, primarily loperamide being used as a drug substitute by substance abusers. Still, it has been rarely reported to cause arrhythmia in a patient with IBS. We present a case of a 33-year-old female with a past medical history of hypertension and depression who presented to the emergency department for evaluation of syncope. She had wide complex tachycardia on electrocardiogram (EKG) with prolonged rate-corrected QT interval (QTc). Her medications, including eluxadoline, Lomotil, and loperamide, were held and she was discharged on mexiletine with normal QTc. She did not have any more incidences of arrhythmia. This case highlights the importance of not overdosing on opioid agonist medications prescribed to treat IBS as these can lead to potentially fatal complications. Physicians have to be judicious in promptly determining that the cause of arrhythmia can also be over-the-counter (OTC) medications.
PubMed: 32467816
DOI: 10.7759/cureus.8243 -
Frontiers in Pediatrics 2021Early diagnosis of long QT type 3 (LQT3) syndrome during the neonatal period is of paramount clinical importance. LQT3 syndrome results in increased mortality and a...
Early diagnosis of long QT type 3 (LQT3) syndrome during the neonatal period is of paramount clinical importance. LQT3 syndrome results in increased mortality and a mutation-specific response to treatment compared to other more common types of LQT syndrome. Mexiletine, a sodium channel blocker, demonstrates a mutation-specific QTc shortening effect in LQT3 syndrome patients. A neonate manifested marked QTc prolongation after birth. An electrocardiogram (ECG) recording was performed due to positive family history of genetically confirmed LQT3 syndrome (SCN5A gene missense mutation Tyr1795Cys), and an association with sudden cardiac death was found in family members. The mexiletine QTc normalizing effect (QTc shortening from 537 to 443 ms), practical issues related to oral mexiletine treatment of our young patient, along with a literature review regarding identification and mexiletine treatment in infants with LQT3 syndrome are presented. Mexiletine could be considered in the treatment of high-risk LQT3 patients already in the neonatal period in addition to b-blocker therapy. Availability of standardized commercial mexiletine pediatric formulas, serum mexiletine level analyses, and future prospective studies are needed to evaluate the potential beneficial effect of early mexiletine treatment on the incidence of future acute cardiac events in these high-risk LQT syndrome patients.
PubMed: 34504812
DOI: 10.3389/fped.2021.674041 -
Neurodegenerative Disease Management Dec 2020Mexiletine is a potential drug in amyotrophic lateral sclerosis (ALS) that has been tested in clinical trials. The objective of this study was to determine the...
Mexiletine is a potential drug in amyotrophic lateral sclerosis (ALS) that has been tested in clinical trials. The objective of this study was to determine the efficacy and safety of mexiletine in ALS via systematic review of existing evidences. Relevant records were searched using major healthcare electronic databases. Data on functional disability, impairment, survival, muscle cramp frequency and severity, and adverse events were obtained. Three relevant randomized controlled trials with 141 patients were included in this review. Mexiletine has no effect on the functional disability, impairment and survival in ALS. However, significant improvement in reducing muscle cramp severity and frequency was shown. The most common adverse effect associated with mexiletine intake among ALS patients are nausea (n = 11, 7.8%) and tremors (n = 5, 3.6%).
Topics: Adult; Aged; Amyotrophic Lateral Sclerosis; Female; Humans; Male; Mexiletine; Middle Aged; Muscle Cramp; Randomized Controlled Trials as Topic; Voltage-Gated Sodium Channel Blockers
PubMed: 32867586
DOI: 10.2217/nmt-2020-0026 -
JMIR Cardio Jan 2023Drug-induced prolongation of the corrected QT interval (QTc) increases the risk for Torsades de Pointes (TdP) and sudden cardiac death. Medication effects on the QTc...
BACKGROUND
Drug-induced prolongation of the corrected QT interval (QTc) increases the risk for Torsades de Pointes (TdP) and sudden cardiac death. Medication effects on the QTc have been studied in controlled settings but may not be well evaluated in real-world settings where medication effects may be modulated by patient demographics and comorbidities as well as the usage of other concomitant medications.
OBJECTIVE
We demonstrate a new, high-throughput method leveraging electronic health records (EHRs) and the Surescripts pharmacy database to monitor real-world QTc-prolonging medication and potential interacting effects from demographics and comorbidities.
METHODS
We included all outpatient electrocardiograms (ECGs) from September 2008 to December 2019 at a large academic medical system, which were in sinus rhythm with a heart rate of 40-100 beats per minute, QRS duration of <120 milliseconds, and QTc of 300-700 milliseconds, determined using the Bazett formula. We used prescription information from the Surescripts pharmacy database and EHR medication lists to classify whether a patient was on a medication during an ECG. Negative control ECGs were obtained from patients not currently on the medication but who had been or would be on that medication within 1 year. We calculated the difference in mean QTc between ECGs of patients who are on and those who are off a medication and made comparisons to known medication TdP risks per the CredibleMeds.org database. Using linear regression analysis, we studied the interaction of patient-level demographics or comorbidities on medication-related QTc prolongation.
RESULTS
We analyzed the effects of 272 medications on 310,335 ECGs from 159,397 individuals. Medications associated with the greatest QTc prolongation were dofetilide (mean QTc difference 21.52, 95% CI 10.58-32.70 milliseconds), mexiletine (mean QTc difference 18.56, 95% CI 7.70-29.27 milliseconds), amiodarone (mean QTc difference 14.96, 95% CI 13.52-16.33 milliseconds), rifaximin (mean QTc difference 14.50, 95% CI 12.12-17.13 milliseconds), and sotalol (mean QTc difference 10.73, 95% CI 7.09-14.37 milliseconds). Several top QT prolonging medications such as rifaximin, lactulose, cinacalcet, and lenalidomide were not previously known but have plausible mechanistic explanations. Significant interactions were observed between demographics or comorbidities and QTc prolongation with many medications, such as coronary disease and amiodarone.
CONCLUSIONS
We demonstrate a new, high-throughput technique for monitoring real-world effects of QTc-prolonging medications from readily accessible clinical data. Using this approach, we confirmed known medications for QTc prolongation and identified potential new associations and demographic or comorbidity interactions that could supplement findings in curated databases. Our single-center results would benefit from additional verification in future multisite studies that incorporate larger numbers of patients and ECGs along with more precise medication adherence and comorbidity data.
PubMed: 36662566
DOI: 10.2196/41055 -
Medicine Jul 2022This study aimed to characterize the genetic, pathological, and clinical alterations of 17 patients in China presenting with nondystrophic myotonia (NDM) and to analyze...
BACKGROUND
This study aimed to characterize the genetic, pathological, and clinical alterations of 17 patients in China presenting with nondystrophic myotonia (NDM) and to analyze the relationship between genotype and clinical phenotype.
METHODS
CLCN1 and SCN4A genes in patients with clinical features and muscle pathology indicative of NDM were sequenced. Furthermore, KCNE3 and CACNA1S genes were assessed in patients with wild-type CLCN1 and SCN4A.
RESULTS
Patients may have accompanying atypical myopathy as well as muscle hypertrophy, secondary dystonia, and joint contracture as determined by needle electromyography. All the study participants were administered mexiletine in combination with carbamazepine and showed significant improvements in myotonia symptoms in response to this therapy. CLCN1 gene mutation was detected in 8 cases diagnosed with myotonia congenital using gene screening. The detected mutations included 5 missense, 2 nonsense, 1 deletion, and 2 insertions. Further gene analysis showed 4 mutations in the SCN4A gene in patients diagnosed with paramyotonia congenita.
CONCLUSIONS
Myotonia congenita and paramyotonia congenita are the predominant forms of NDM in China. NDM may be best diagnosed using genetic analysis in associated with clinical features.
Topics: Chloride Channels; Humans; Mutation; Myotonia; Myotonic Disorders; NAV1.4 Voltage-Gated Sodium Channel
PubMed: 35866763
DOI: 10.1097/MD.0000000000029591