Clinical Pharmacology Study of Oral Edaravone in Amyotrophic Lateral Sclerosis Patients With Gastrostomy

Inclusion Criteria: The key criteria are listed below. * Patients aged between 20 and 80 years at the time of informed consent * Japanese patients * Among patients with ALS, those "Clinically definite ALS," "Clinically probable ALS" or "Clinically probable-laboratory-supported ALS" according to El Escorial Revised Airlie House criteria * ALS Patients with gastrostomy * Patients who can consent to contraception * Patients who have thoroughly understood the contents of the study and voluntarily provided written informed consent to participate in the study Exclusion Criteria: The key criteria are listed below. * Patients in whom the possibility could not be ruled out that the current symptoms were symptoms of a disease requiring differential diagnosis, such as cervical spondylosis and multifocal motor neuropathy * Patients undergoing treatment for malignancy. * Patients who have presence of clinically significant liver, heart, or renal disease requiring hospitalization (except ALS) and infections requiring antibiotics. Patients who have a problem in general condition and are judged ineligible by the Investigator * Body mass index (BMI) of \<15.0 or \>30.0, or a body weight of \<40 kg * Patients judged by the investigator (or subinvestigator) to be unsuitable for the study for any other reason