Key Summary
- Lupin got expanded marketing authorisation from EMA for NaMuscla for children.
- NaMuscla is the only antimyotonic agent licensed to treat symptomatic myotonia in children aged 6 to 11 years.
- Myotonic disorders are a group of heterogeneous, inherited, neuromuscular disorders characterised by a shared symptom called myotonia.
Lupin Limited has announced that the European Medicines Agency (EMA) has approved a change to the terms of its marketing authorisation for NaMuscla (mexiletine), supported by data from a Pediatric Investigation Plan (PIP).
NaMuscla is now the only antimyotonic medicine authorised for symptomatic treatment of myotonia, a rare disease, in children aged 6–11 years who weigh at least 20 kg, as well as adolescents (12–17) and adults (≥18) with non‑dystrophic myotonic disorders.
The approval adds two lower capsule strengths (62 mg and 83 mg) alongside the existing 167 mg adult strength, and updates the indication to explicitly include the paediatric age groups.
Clinical trials have shown that NaMuscla, at total daily doses between 167 mg and 500 mg, reduces myotonia versus placebo by lowering skeletal muscle hyperexcitability through use‑dependent blockade of voltage‑gated sodium channels - an effect that does not depend on the underlying channel defect.
Trial results also indicated improvements in quality of life and functional measures. Gastrointestinal discomfort was the most commonly reported adverse event, and overall the drug was considered well tolerated.
Claus Jepsen, President, Global Specialty, Lupin, said, “This EMA approval for Pediatric Indication of NaMuscla represents a significant step forward for patients and families living with non-dystrophic myotonic disorders - especially children, where options are scarce. At Lupin, we remain committed to broadening access to therapies that improve outcomes across every stage of care.”
Lupin plans to roll out the new strengths and paediatric indication across Europe, subject to national implementation timelines and reimbursement processes.
Myotonia refers to delayed muscle relaxation after voluntary contraction, affecting actions such as handshakes, blinking, walking, or climbing stairs. Non‑dystrophic myotonias are a rare subgroup (prevalence around 1 in 100,000) caused by inherited mutations in ion channels of skeletal muscle membranes.
