Namuscla

Pharmaceutical company: Lupin

Namuscla works by blocking a channel in the membrane of muscle cells that allow sodium ions (electrically charged particles) to pass in and out. Sodium ions play a role in the communication of electrical signals between the brain and muscles, which tell a muscle when to contract and relax.

In people with non-dystrophic myotonic disorders, the channels are over-active. This means repeated electrical signals are sent to the muscle. This causes muscles to take longer to relax, become tense and stiff. Blocking the channels reduces the repeated signals and should reduce muscle stiffness.

Namuscla comes as a capsule that can be swallowed.

Namuscla has been recommended as an option for treating the symptoms of myotonia in adults with non-dystrophic myotonic disorders in the UK and is available on the NHS. Please consult your clinical team for more information.

England, Wales and Northern Ireland

Read the full National Institute for Health and Care Excellence (NICE) guidance.

Scotland

Read the full Scottish Medicines Consortium (SMC) guidance.

We are proud to have played a role in ensuring Namuscla is available for adults with non-dystrophic myotonic disorders. Throughout the assessment processes, we worked closely with the community, developed written responses, and nominated and supported patient experts to share their views and experiences.

Evidence from the phase 3 MYOMEX clinical trial was used in the UK assessment of Namuscla. This was a two-part trial. In part one, participants were randomly assigned to receive either the treatment (12 participants) or the placebo (dummy drug, 13 participants) for 18-22 days. All participants then stopped taking the treatment or placebo for 4-8 days. In part two, the participants crossed over, meaning those who originally took the treatment received the placebo and vice versa, for another 18-22 days.

When participants took Namuscla, they reported a statistically significant improvement (78%) in stiffness compared to placebo, measured by the visual analogic scale (VAS). This is a self-reported scale from “no stiffness at all” to “worst possible stiffness”. This suggests that it is likely Namuscla improves stiffness.

Participants who received Namuscla also reported a significant improvement in quality of life through the INQoL questionnaire. This assesses the impact of the condition and symptoms on different areas of their life, such as pain, weakness, independence and social relationships. Namuscla was also found to be safe.

Last updated: 18/02/2025