Bioequivalence and food effect assessment for a new risdiplam tablet formulation in healthy volunteers

The approved risdiplam dose for patients weighing ≥20kg is 5 mg. The current available formulation is an oral solution that is drawn up in a syringe every day. A bioequivalent tablet formulation would provide patients weighing ≥20kg with a simpler daily option of swallowing a tablet or dispersing it in water. Part 1 of this healthy volunteer study (NCT04718181) assessed the relative oral bioavailability and the effects of food and stomach pH on, two new risdiplam tablet formulations Part 2 of the study assessed the bioequivalence and food effect of the most promising tablet formulation from Part 1 versus oral risdiplam solution. Using a four-way crossover design, each volunteer randomly received a single dose of 5 mg risdiplam oral solution in both fed and fasted states, and a single 5 mg risdiplam tablet (either swallowed whole or dispersed in water) in both fed and fasted states. The new risdiplam 5 mg tablet formulation was shown to be bioequivalent to the oral solution of risdiplam, based on the pharmacokinetic parameters area under the concentration-time curve and maximum concentration. In addition, no relevant impact of food on the exposure of risdiplam for either the oral solution or the tablet was found.