Adherence to riluzole in patients with amyotrophic lateral sclerosis: an observational study

Alessandro IntronaNeurology Unit, Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari “Aldo Moro,” Bari, Italy

Eustachio D’ErricoNeurology Unit, Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari “Aldo Moro,” Bari, Italy

Boris ModugnoNeurology Unit, Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari “Aldo Moro,” Bari, Italy

Antonio ScarafinoNeurology Unit, Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari “Aldo Moro,” Bari, Italy

Angela FraddosioNeurology Unit, Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari “Aldo Moro,” Bari, Italy

Eugenio DistasoNeurology Unit, Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari “Aldo Moro,” Bari, Italy

Irene TempestaNeurology Unit, Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari “Aldo Moro,” Bari, Italy

Antonella MastronardiNeurology Unit, Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari “Aldo Moro,” Bari, Italy

Isabella Laura SimoneNeurology Unit, Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari “Aldo Moro,” Bari, ItalyCorrespondence[email protected]

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Abstract

Objective

Riluzole is the first drug approved to treat amyotrophic lateral sclerosis (ALS). Recently, an oral suspension (OS) of riluzole was made available. Thus, the aim of our study was to evaluate the adherence to 2 formulations of riluzole in patients with ALS.

Patients and methods

We enrolled 45 consecutive patients with ALS. At disease diagnosis, riluzole was prescribed in 2 different formulations depending on the severity of dysphagia (27/45 patients received tablets and 18/45 patients received OS). Side effects (SEs) and treatment adherence were investigated using a clinical questionnaire including the ©Morisky 8-item Medication Adherence Questionnaire.

Results

Gastroenteric complaints were the most frequent SEs (58% in the tablet group and 48% in the OS group), followed by those at the nervous system (29% and 40%, respectively). No serious SEs related to treatment were reported. The rate of adherence to riluzole was independent of the formulation of the drug and consistent with other medications assumed for comorbidities (p=0.004). In the tablet group, low adherence was caused by SEs in 55.6% and by dysphagia in 44.4% of patients. In the OS group, SEs caused low adherence in 75% of patients. Independently of the drug formulation, patients with high or medium adherence to riluzole had a higher progression rate (p=0.002 and p=0.009, respectively) and a shorter time to generalization (TTG; p=0.01), compared to those with low adherence.

Conclusion

Gastroenteric symptoms were the most frequent SE related to tablet as well as OS. The rate of adherence was independent of the formulation of riluzole and the number of medications assumed for comorbidities, and it was consistent with the severity of the disease. The low adherence was caused by dysphagia and SEs in the tablet group, whereas it was caused prevalently by SEs in the OS group.

Keywords:

Supplementary materials

Figure S1 Questionnaire on clinical and pharmacological features related to ALS and comorbidities.

Abbreviations: ALS, amyotrophic lateral sclerosis; ALSFRS-r, ALS Functional Rating Scale – revised; MMT-m, Manual Muscle Testing – medium; NSAIDs, nonsteroidal anti-inflammatory drugs.

Acknowledgments

We thank Dr Antonio Leo who was involved in the conception and drawing up of the clinical questionnaire. Use of the ©MMAS is protected by US copyright laws. Permission for use is required and was obtained for this study. A license agreement is available from Donald E Morisky, MMAS Research LLC, 14725 NE 20th Street, Bellevue, WA 98007, USA, or from [email protected].

Author contributions

Isabella Laura Simone and Eustachio D’Errico conceived and designed the study. Eustachio D’Errico, Alessandro Introna, Boris Modugno and Isabella Laura Simone performed the experiments. Alessandro Introna, Eustachio D’Errico, Boris Modugno and Isabella Laura Simone analyzed the data. Eustachio D’Errico, Alessandro Introna, Eugenio Distaso, Antonio Scarafino, Angela Fraddosio, Irene Tempesta and Antonella Mastronardi contributed to acquisition of data, Alessandro Introna and Isabella Laura Simone drafted the paper. Isabella Laura Simone drafted/revised the manuscript for content, including medical writing for content, study concept or design, analysis or interpretation of data, statistical analysis and study supervision and coordination. All authors contributed toward data analysis, drafting and critically revising the paper and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest in this work.