This study is evaluating single administration of two dose levels of ERX-963 to explore the relationship between dose, safety, tolerability, exposure and clinical benefit. This is a multi-center, randomized, double-blind, placebo-controlled, two-treatment period crossover study in two cohorts of participants with DM1.
Participants who have consented and meet eligibility criteria will receive two treatments, placebo and ERX-963, in a randomized crossover fashion with a washout period between the treatments. On treatment days, participants will receive treatment followed by repeated blood collection for pharmacokinetic analysis and administration of a battery of outcome measures relevant to sleep and cognition.