Part 1 of the study is an exploratory comparison of the relative oral bioavailability of the two dispersible tablets versus risdiplam powder for oral solution as the reference. The effect of food on the bioavailability of the two dispersible tablets will be assessed by comparing fed and fasted states in a five-way crossover manner. It will also be assessed whether antacids (omeprazole) have an impact on the bioavailability of the dispersible tablets in a two-way crossover manner. The food effect on the risdiplam oral solution will also be assessed by comparing fed and fasted states in a two-way crossover manner.~In Part 2, based on the data obtained in Part 1 and provided data support further evaluation, a bioequivalence assessment and a food-effect evaluation will be conducted in two groups with the selected dispersible tablet formulation. Each group will randomly receive, in a four-way crossover, a single dose of risdiplam oral solution 5 mg in both fed and fasted states, and a single dose of the selected dispersible tablet in both fed and fasted states.~In Part 3, provided Part 1 data support further evaluation of the second formulation, the second formulation may be assessed for bioequivalence in the same way as described in Part 2.~Enrollment of the same participant in more than one cohort or group will not be permitted regardless of the study part.
The study is a randomized, single oral dose, crossover study in up to three parts to investigate the relative bioavailability and bioequivalence of two different formulations of risdiplam 5 mg (dispersible tablets) versus the current risdiplam oral solution formulation in healthy male and female participants. The effect of food on these two dispersible tablets and the current oral solution will be studied, as well as the effect of omeprazole on the dispersible tablets.