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Azonbakin S, Adovoekpe D, Adjagba M, Alao J, Sagbo G, Adjien C, Laleye A. Becker congenital myotonia in black African with molecular findings. Egypt J Med Hum Genet 2022. [DOI: 10.1186/s43042-022-00290-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Congenital myotonia is a congenital disorder that affects skeletal muscles with myotonia. Affected muscles show stiffness and pain sometimes. The two major types of myotonia congenita are known as Thomsen disease and Becker disease. These conditions are distinguished by the severity of their symptoms and their patterns of inheritance. The causative factor is mutations in CLCN1 gene. Myotonia congenita is rarely reported in black especially in black African.
Case presentation
This is a case report of Becker Congenital Myotonia in a 36-year-old male from Benin. The symptoms arose at the age of 7 years with regular and progressive course and muscles pains. Electromyogram, blood sampling, laboratory investigations and muscles biopsy confirm the diagnostic with molecular finding.
Conclusion
The authors report a case of Becker congenital myotonia in a black African with molecular confirmation.
Mexiletine was used as symptomatic agent with good results.
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Chapman AM, Schurer M, Weijers L, Omar A, Lee H, Weidenfeller AZ, Ellis C, Sonecha S, Schneider-Gold C. Improving the understanding of how patients with non-dystrophic myotonia are selected for myotonia treatment with mexiletine (NaMuscla): outcomes of treatment impact using a European Delphi panel. BMC Neurol 2021; 21:467. [PMID: 34852780 PMCID: PMC8633892 DOI: 10.1186/s12883-021-02491-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 11/10/2021] [Indexed: 11/17/2022] Open
Abstract
Background Non-dystrophic myotonias (NDMs) comprise muscle chloride and sodium channelopathies due to genetic defects of the CLCN1- and SCN4A-channels. No licensed antimyotonic treatment has been available until approval of mexiletine (NaMuscla®) for adult patients by the EMA in December 2018. This Delphi panel aimed to understand how outcomes of the pivotal phase III Mexiletine study (MYOMEX) translate to real world practice and investigate health resource use, quality of life and the natural history of NDM to support economic modelling and facilitate patient access. Methods Nine clinical experts in treating NDM took part in a two-round Delphi panel. Their knowledge of NDM and previous use of mexiletine as an off-label treatment prior to NaMuscla’s approval ensured they could provide both qualitative context and quantitative estimates to support economic modelling comparing mexiletine (NaMuscla) to best supportive care. Consensus in four key areas was sought: healthcare resource utilization (HRU), treatment with mexiletine (NaMuscla), patient quality of life (QoL), and the natural history of disease. Concept questions were also asked, considering perceptions on the feasibility of mapping the validated Individualized Neuromuscular Quality of Life (INQoL) instrument to the generic EQ-5D™, and the potential impact on caregiver QoL. Results Consensus was achieved for key questions including the average long-term dosage of mexiletine (NaMuscla) in practice, the criteria for eligibility of myotonia treatment, the clinical importance of QoL outcomes in MYOMEX, the higher proportion of patients with increased QoL, and the reduction in the need for mental health resources for patients receiving mexiletine (NaMuscla). While consensus was not achieved for other questions, the results demonstrated that most experts felt mexiletine (NaMuscla) reduced the need for HRU and was expected to improve QoL. The QoL mapping exercise suggested that it is feasible to map domains of INQoL to EQ-5D. Points of interest for future research were identified, including that mexiletine (NaMuscla) may slow the annual decrease in QoL of patients over their lifetime, and a significant negative impact on QoL for some caregivers. Conclusions This project successfully provided data from an informed group of clinical experts, complementing the currently available clinical trial data for mexiletine (NaMuscla) to support patient access decisions. Supplementary Information The online version contains supplementary material available at 10.1186/s12883-021-02491-3.
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Affiliation(s)
| | | | | | - Amer Omar
- Lupin Atlantis Holdings SA, Zug, Switzerland
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Chakravarty K, Lal V, Ray S. A Novel Mutation in the CLCN1 Gene Causing Autosomal Recessive Myotonia Congenita in Siblings. Ann Indian Acad Neurol 2021; 24:605-606. [PMID: 34728966 PMCID: PMC8513945 DOI: 10.4103/aian.aian_970_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 09/24/2020] [Accepted: 10/11/2020] [Indexed: 11/26/2022] Open
Affiliation(s)
| | - Vivek Lal
- Department of Neurology, PGIMER, Chandigarh, India
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Vicart S, Franques J, Bouhour F, Magot A, Péréon Y, Sacconi S, Nadaj-Pakleza A, Behin A, Zahr N, Hézode M, Fournier E, Payan C, Lacomblez L, Fontaine B. Efficacy and safety of mexiletine in non-dystrophic myotonias: A randomised, double-blind, placebo-controlled, cross-over study. Neuromuscul Disord 2021; 31:1124-1135. [PMID: 34702654 DOI: 10.1016/j.nmd.2021.06.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 06/11/2021] [Accepted: 06/22/2021] [Indexed: 11/30/2022]
Abstract
The MYOMEX study was a multicentre, randomised, double-blind, placebo-controlled, cross-over study aimed to compare the effects of mexiletine vs. placebo in patients with myotonia congenita (MC) and paramyotonia congenita (PC). The primary endpoint was the self-reported score of stiffness severity on a 100 mm visual analogic scale (VAS). Mexiletine treatment started at 200 mg/day and was up-titrated by 200 mg increment each three days to reach a maximum dose of 600 mg/day for total treatment duration of 18 days for each cross-over period. The modified intent-to-treat population included 25 patients (13 with MC and 12 with PC; mean age, 43.0 years; male, 68.0%). The median VAS score for mexiletine was 71.0 at baseline and decreased to 16.0 at the end of the treatment while the score did not change for placebo (81.0 at baseline vs. 78.0 at end of treatment). A mixed effects linear model analysis on ranked absolute changes showed a significant effect of treatment (p < 0.001). The overall score of the Individualized Neuromuscular Quality of Life questionnaire (INQoL) was significantly improved (p < 0.001). No clinically significant adverse events were reported. In conclusion, mexiletine improved stiffness and quality of life in patients with nondystrophic myotonia and was well tolerated.
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Affiliation(s)
- Savine Vicart
- Assistance Publique-Hôpitaux de Paris, Sorbonne Université, INSERM, Service of Neuro-Myology, Muscle Channelopathies Reference Center and UMR 974, Institute of Myology, University Hospital Pitié-Salpêtrière, Paris, France.
| | - Jérôme Franques
- Assistance Publique-Hôpitaux de Marseille, Department of Neurology and Neuromuscular Diseases, La Timone Hospital, Marseille, France
| | - Françoise Bouhour
- Electroneuromyography and Neuromuscular Disorders Department, Hospices Civils de Lyon, University Hospital of Lyon, France
| | - Armelle Magot
- Reference Centre for Neuromuscular disorders AOC, University Hospital, Hôtel-Dieu, Nantes, France
| | - Yann Péréon
- Reference Centre for Neuromuscular disorders AOC, University Hospital, Hôtel-Dieu, Nantes, France
| | - Sabrina Sacconi
- Université Côte d'Azur, Peripheral Nervous System & Muscle Department, Pasteur 2 Hospital, Centre Hospitalier Universitaire de Nice, Nice, France
| | - Aleksandra Nadaj-Pakleza
- Reference Centre for Neuromuscular disorders AOC, Neurology Department, University Hospital of Angers, Angers, France
| | - Anthony Behin
- Assistance Publique-Hôpitaux de Paris, Service of Neuro-Myology, Reference Centre for Neuromuscular disorders NEIdF, University Hospital Pitié-Salpêtrière, Paris, France
| | - Noël Zahr
- Assistance Publique-Hôpitaux de Paris, Sorbonne Université, Pharmacology Department, University Hospital Pitié-Salpêtrière, Paris, France
| | - Marianne Hézode
- Assistance Publique-Hôpitaux de Paris, Sorbonne Université, Department of Clinical Neurophysiology, University Hospital Pitié-Salpêtrière, Paris, France
| | - Emmanuel Fournier
- Assistance Publique-Hôpitaux de Paris, Sorbonne Université, Department of Clinical Neurophysiology, University Hospital Pitié-Salpêtrière, Paris, France
| | - Christine Payan
- Assistance Publique-Hôpitaux de Paris, Sorbonne Université, Pharmacology Department, University Hospital Pitié-Salpêtrière, Paris, France
| | - Lucette Lacomblez
- Assistance Publique-Hôpitaux de Paris, Sorbonne Université, Pharmacology Department, University Hospital Pitié-Salpêtrière, Paris, France; Assistance Publique-Hôpitaux de Paris, Sorbonne Université, INSERM U 1422, Neurology Department, University Hospital Pitié-Salpêtrière, Paris, France
| | - Bertrand Fontaine
- Assistance Publique-Hôpitaux de Paris, Sorbonne Université, INSERM, Service of Neuro-Myology, Muscle Channelopathies Reference Center and UMR 974, Institute of Myology, University Hospital Pitié-Salpêtrière, Paris, France
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Catalano A, Franchini C, Carocci A. Voltage-Gated Sodium Channel Blockers: Synthesis of Mexiletine Analogues and Homologues. Curr Med Chem 2021; 28:1535-1548. [PMID: 32364065 DOI: 10.2174/0929867327666200504080530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 03/13/2020] [Accepted: 03/14/2020] [Indexed: 11/22/2022]
Abstract
Mexiletine is an antiarrhythmic drug belonging to IB class, acting as sodium channel blocker. Besides its well-known activity on arrhythmias, its usefulness in the treatment of myotonia, myotonic dystrophy and amyotrophic lateral sclerosis is now widely recognized. Nevertheless, it has been retired from the market in several countries because of its undesired effects. Thus, several papers were reported in the last years about analogues and homologues of mexiletine being endowed with a wider therapeutic ratio and a more selectivity of action. Some of them showed sodium channel blocking activity higher than the parent compound. It is noteworthy that mexiletine is used in therapy as a racemate even though a difference in the activities of the two enantiomers was widely demonstrated, with (-)-(R)-enantiomer being more active: this finding led several research groups to study mexiletine and its analogues and homologues in their optically active forms. This review summarizes the different synthetic routes used to obtain these compounds. They could represent an interesting starting point to new mexiletine-like compounds without common side effects related to the use of mexiletine.
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Affiliation(s)
- Alessia Catalano
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", via Orabona 4, 70126 Bari, Italy
| | - Carlo Franchini
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", via Orabona 4, 70126 Bari, Italy
| | - Alessia Carocci
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", via Orabona 4, 70126 Bari, Italy
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Cirillo G, Todisco V, Tedeschi G. The differential diagnosis of myotonic syndromes: A case report-guided and neurophysiologic approach. J Neurol Sci 2016; 360:98-99. [DOI: 10.1016/j.jns.2015.11.054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Revised: 11/24/2015] [Accepted: 11/28/2015] [Indexed: 11/23/2022]
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Odrzywolski K, Johnson NE, Twydell PT. Myotonia congenita in a patient who presented with diplopia and ptosis. Muscle Nerve 2013; 47:307-8. [PMID: 23349086 DOI: 10.1002/mus.23634] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 08/06/2012] [Accepted: 08/12/2012] [Indexed: 11/06/2022]
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Desaphy JF, Costanza T, Carbonara R, Conte Camerino D. In vivo evaluation of antimyotonic efficacy of β-adrenergic drugs in a rat model of myotonia. Neuropharmacology 2012; 65:21-7. [PMID: 23000075 PMCID: PMC3546166 DOI: 10.1016/j.neuropharm.2012.09.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Revised: 07/27/2012] [Accepted: 09/04/2012] [Indexed: 11/26/2022]
Abstract
The sodium channel blocker mexiletine is considered the first-line drug in myotonic syndromes, a group of muscle disorders characterized by membrane over-excitability. We previously showed that the β-adrenoceptor modulators, clenbuterol and propranolol, block voltage-gated sodium channels in a manner reminiscent to mexiletine, whereas salbutamol and nadolol do not. We now developed a pharmacological rat model of myotonia congenita to perform in vivo preclinical test of antimyotonic drugs. Myotonia was induced by i.p. injection of 30 mg/kg of anthracene-9-carboxylic acid (9-AC), a muscle chloride channel blocker, and evaluated by measuring the time of righting reflex (TRR). The TRR was prolonged from <0.5 s in control conditions to a maximum of ∼4 s, thirty minutes after 9-AC injection, then gradually recovered in a few hours. Oral administration of mexiletine twenty minutes after 9-AC injection significantly hampered the TRR prolongation, with an half-maximum efficient dose (ED(50)) of 12 mg/kg. Both propranolol and clenbuterol produced a dose-dependent antimyotonic effect similar to mexiletine, with ED(50) values close to 20 mg/kg. Antimyotonic effects of 40 mg/kg mexiletine and propranolol lasted for 2 h. We also demonstrated, using patch-clamp methods, that both propranolol enantiomers exerted a similar block of skeletal muscle hNav1.4 channels expressed in HEK293 cells. The two enantiomers (15 mg/kg) also showed a similar antimyotonic activity in vivo in the myotonic rat. Among the drugs tested, the R(+)-enantiomer of propranolol may merit further investigation in humans, because it exerts antimyotonic effect in the rat model, while lacking of significant activity on the β-adrenergic pathway. This study provides a new and useful in vivo preclinical model of myotonia congenita in order to individuate the most promising antimyotonic drugs to be tested in humans.
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Affiliation(s)
- Jean-François Desaphy
- Section of Pharmacology, Department of Pharmacy, University of Bari-Aldo Moro, Via Orabona 4 - Campus, 70125 Bari, Italy.
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Catalano A, Desaphy JF, Lentini G, Carocci A, Di Mola A, Bruno C, Carbonara R, De Palma A, Budriesi R, Ghelardini C, Perrone MG, Colabufo NA, Conte Camerino D, Franchini C. Synthesis and Toxicopharmacological Evaluation of m-Hydroxymexiletine, the First Metabolite of Mexiletine More Potent Than the Parent Compound on Voltage-Gated Sodium Channels. J Med Chem 2012; 55:1418-22. [DOI: 10.1021/jm201197z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | | | | | | | | | | | | | | | - Roberta Budriesi
- Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126
Bologna, Italy
| | - Carla Ghelardini
- Dipartimento
di Farmacologia
Preclinica e Clinica, Università di Firenze, Viale Pieraccini 6, 50139 Firenze, Italy
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Mutti FG, Fuchs CS, Pressnitz D, Sattler JH, Kroutil W. Stereoselectivity of Four (R)-Selective Transaminases for the Asymmetric Amination of Ketones. Adv Synth Catal 2011. [DOI: 10.1002/adsc.201100558] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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