Scottish Medicines Consortium approves Lupin's NaMuscla® (mexiletine) to treat symptomatic myotonia in adults with non-dystrophic myotonic disorders (NDM)

Scottish Medicines Consortium approves NaMuscla® (mexiletine) to treat symptomatic myotonia in adults with non-dystrophic myotonic disorders (NDM)

Slough, UK, 8 December 2020: Lupin welcomes the Scottish Medicines Consortium’s (SMC) decision to approve the use of NaMuscla® (mexiletine) for the treatment of symptomatic myotonia in adult patients with non-dystrophic myotonic disorders (NDM) in Scotland.1

NaMuscla is the first licensed medicine to treat symptomatic myotonia in adult patients with NDM3, an ultra-rare genetic neuromuscular disorder in which the sufferer's muscles are slow to relax after movement. These symptoms occur intermittently and unexpectedly, often causing pain, muscle weakness, fatigue and impairment of physical activities.2

 “We are delighted that NaMuscla has been approved via the SMC fast track process and are pleased to offer a confidential patient access scheme to ensure patients in Scotland can access the only licensed medicine for this rare debilitating disease,” said Ben Ellis, Lupin UK General Manager. “Scottish patients benefit from the SMC’s tailored approach to rare disease medicine health technology assessments. Lupin is committed to ensuring all eligible patients can access NaMuscla, irrespective of where they live in the UK.”

The SMC’s approval applies only in the context of the agreed confidential NHS Scotland Patient Access Scheme (PAS).

For further information or media enquiries please contact:

Consilium Strategic Communications
Sukaina Virji / Lizzie Seeley
Tel: +44 (0)7738 499212

About Non-Dystrophic Myotonias (NDM)
Non-dystrophic myotonias (NDM) are a heterogenous group of rare neuromuscular disorders caused by mutations within ion channels in the sarcolemma membrane of skeletal muscles and affects 1 in 100,000 people.2 Non-dystrophic myotonias exhibit both sodium and chloride channelopathies which result in altered membrane excitability. The major clinical manifestation of the non-dystrophic myotonias is muscle stiffness as a consequence of the myotonia- delayed muscle relaxation after voluntary contraction. Additional common symptoms include pain, weakness and fatigue, and can affect different parts of the body, such as legs, arms or facial muscles, more severely.2
Myotonia in NDM patients has an onset in childhood and persists across their lifetime. Although not life limiting, patients with non-dystrophic myotonia can experience significant lifetime morbidity due to stiffness and pain related to myotonia. Patients may perceive that myotonia increases in severity over time, impacting daily life. Myotonia is described by patients in a variety of ways (stiffness, cramps, pain, difficulty releasing a fist, or difficulty swallowing or eating) which can contribute to substantial delays in diagnosis and treatment, leading to decreased patient quality-of-life and often significant disability.7

About mexiletine
In randomized controlled trials 3-5 mexiletine has been shown to significantly reduce myotonia compared to placebo in adult patients with NDM, reducing skeletal muscle hyperexcitability through its use-dependent, voltage-gated, sodium channel blocking actions which are independent of the cause of channel function. This resulted in an improvement in patient quality-of-life and other functional outcomes.The most commonly reported adverse reactions in patients treated with mexiletine are abdominal pain (12%), vertigo (8%) and insomnia (12%), demonstrating mexiletine has a good safety profile.3,6

About Lupin Limited
Lupin is an innovation-led transnational pharmaceutical company headquartered in Mumbai, India. The Company develops and commercializes a wide range of branded and generic formulations, biotechnology products and APIs in over 100 markets in the U.S., India, South Africa and across Asia Pacific (APAC), Latin America (LATAM), Europe and Middle East regions.

The Company supplies medicines in cardiovascular, anti-diabetic, and respiratory segments and has significant presence in the anti-infective, gastro-intestinal (GI), central nervous system (CNS) and women’s health areas. Lupin is the 3rd largest pharmaceutical company in the U.S. by prescriptions and 5th in India by global revenues. The Company invests 10.3 % of its revenues on research and development.
Lupin has fifteen manufacturing sites, seven research centers, more than 20,000 professionals working globally.8


  1. Scottish Medicines Consortium Final decision December 2020.  Last accessed 7/12/2020
  2. Matthews E, Fialho D, Tan SV, Venance SL, Cannon SC, Sternberg D, et al. The non-dystrophic myotonias: molecular pathogenesis, diagnosis and treatment. Brain 2010; 133 (Pt 1): 9–22.
  3. Namuscla summary of product characteristics,  Last accesses Nov 2020
  4. Statland JM, Bundy BN, Wang Y, et al. Consortium for Clinical Investigation of Neurologic Channelopathies. Mexiletine for symptoms and signs of myotonia in nondystrophic myotonia: a randomized controlled trial. JAMA. 2012; 308(13):1357–1365. [PubMed: 23032552]
  5. Stunnenberg B.C, Raaphorst J, Groenewoud al. Effect of mexiletine on muscle stiffness in patients with nondystrophic myotonia evaluated using aggregated N-of-1 trials. JAMA. 2018; 320: 2344-2353
  6. Suetterlin  KJ, Bugiardini  E, Kaski  JP,  et al.  Long-term safety and efficacy of mexiletine for patients with skeletal muscle channelopathies.  JAMA Neurol. 2015;72(12):1531-1533.
  7. Trivedi JR, Bundy B, Statland J, et al; CINCH Consortium. Non-dystrophic myotonia: prospective study of objective and patient reported outcomes. Brain. 2013;136(pt 7):2189-2200. doi:10.1093/brain
  8. LUPIN Limited Investor Report FY2020 (Accessed Online: 3rdJuly 2020)