Riluzole Oral Suspension for the Treatment of Amyotrophic Lateral Sclerosis: Texture and Compatibility with Food Thickeners Evaluation

Riluzole 5 mg/mL oral suspension is the only licensed liquid medicine to treat Amyotrophic Lateral Sclerosis (ALS) orally. As more than 80% of ALS patients develop dysphagia, an oral liquid formulation provides an important therapeutic option. The Riluzole 5 mg/mL oral suspension is administered by means of the graduated oral dosing syringe included in the medicine package. Its concentration (5 mg/mL) is consistent with a small and easy to measure volume (10 mL) to deliver the prescribed 50-mg dose twice daily. This work had a dual objective. The first was to evaluate the texture of the Riluzole 5 mg/mL oral suspension according to the International Dysphagia Diet Standardisation Initiative (IDDSI) flow test. Results of this experiment indicated that Riluzole 5 mg/mL oral suspension would basically fall under the “mildly thick” IDDSI descriptors. This is an important feature because thick fluids facilitate a safer swallow in patients with dysphagia. As a second objective, we evaluated for scientific purposes the compatibility of Riluzole 5 mg/mL oral suspension with some of the most common food thickeners available on the market. Intimate mixtures of the Riluzole 5 mg/mL oral suspension with thickeners were evaluated for appearance, pH, Riluzole assay and Riluzole related substances immediately after preparation and after two hours at room temperature. Riluzole 5 mg/mL oral suspension resulted to be compatible with all the marketed thickeners tested.