Open-label Study to Evaluate Safety, Tolerability and PK of BHV-0223 in ALS

Inclusion Criteria: 1. Subjects with diagnosed ALS by the revised El Escorial diagnostic criteria, including laboratory supported probable, probable, or definite ALS; 2. Subjects who have never taken riluzole tablets, OR Subjects who previously took riluzole tablets but discontinued at least 1 month prior to the screening visit. Subjects must not have had ALT or AST \> 5 x ULN while taking riluzole tablets, or any other clinically significant tolerability issues (e.g., hypersensitivity reactions) in the judgement of the investigator; 3. Subjects determined by the investigator to be medically stable; 4. Subjects determined by the investigator to be willing and physically able to complete the study as designed, with or without caregiver assistance. Exclusion Criteria: 1. Target Disease Exceptions 2. Medical History Exceptions 1. Subject is known to have a current diagnosis of acute or chronic viral hepatitis; 2. Subject is known to have any other acute or chronic liver disease that is clinically significant in the investigator's judgment; 3. Subject has a history of a clinically significant medical condition that would interfere with the subject's ability to comply with study instructions, would place the subject at increased risk, or might confound the interpretation of the study results in the investigator's judgment; 4. Any other sound medical, psychiatric and/or social reason in the investigator's judgment; 3. Physical and Laboratory Test Findings 1. Positive urine pregnancy test in WOCBP at screening; 2. Subject has evidence of organ dysfunction or any clinically significant deviation from normal in physical examination, vital signs, or other determinations beyond what is consistent with the target population, in the investigator's judgment; 3. Subject has liver function testing abnormalities (ALT, AST , or total bilirubin) that are \> 1 x ULN; 4. Other Exclusions a. Subjects who are unable to be compliant with the visit schedule or protocol procedures.