This study focuses on individuals with Autosomal Dominant RYR1-Related Myopathy, a rare muscle disease caused by specific changes in the RYR1 gene that affect how muscles function. The purpose of the study is to evaluate the effectiveness and safety of a medication called Surlorian, also known as ARM210 or S48168, compared to a placebo.

Participants will receive either the study drug or a placebo in the form of a film-coated tablet taken by oral use. To ensure the results are unbiased, the study uses a double-blind method, meaning neither the participants nor the researchers know which treatment is being administered. Over a period of approximately 28 days, the effects of the medication on muscle strength and how quickly muscles tire will be monitored.