Riluzole pharmacokinetics in young patients with spinal muscular atrophy.

Aims: The objective of the present study was to assess the pharmacokinetics of riluzole in patients with spinal muscular atrophy (SMA).

Methods: Fourteen patients were enrolled in an open-label, nonrandomized and repeat-dose pharmacokinetic study. All participants were assigned to receive 50mg riluzole orally for 5 days. Riluzole plasma concentrations were determined from samples obtained at day 5.

Results: The pharmacokinetic analysis demonstrated that a dose of 50mg once a day was sufficient to obtain a daily total exposure [AUC(0,24h)=2257ng ml(-1) h] which was comparable with results obtained in adult healthy volunteers or ALS patients in whom a dose of 50mg twice a day is recommended. The pharmacokinetic simulation demonstrated that the administration of 50mg twice a day could result in higher concentrations, hence reduced safety margin.

Conclusion: The dose of 50mg once a day was chosen for the clinical trial evaluating the efficacy of riluzole in SMA patients.