This study is designed to evaluate whether a combination of N-acetylcysteine (NAC) and EH-301 can slow down or improve symptoms of amyotrophic lateral sclerosis (ALS). Researchers will assess changes in disease progression using the ALS Functional Rating Scale-Revised (ALSFRS-R), a standard tool for measuring daily functioning in people with ALS.

The main question is whether taking NAC together with EH-301 can prevent symptom worsening and possibly improve existing ALS symptoms.

Participants will be randomly assigned to receive either the active combination (NAC + EH-301) or matching placebos for 6 months. During this period, they will attend regular clinic visits for evaluations, tests, and safety monitoring.

After completing the initial 6-month phase, all participants may choose to join a 6-month open-label extension, where everyone receives the active treatment regardless of their original group.

Inclusion Criteria:

1. Patients diagnosed with ALS according to the Gold Coast criteria;

2. Disease duration ≤ 18 months;

3. Men and women aged 18 to 75 years;

4. Total ALSFRS-R score ≥ 30 for all 12 categories;

5. Forced vital capacity (FVC) ≥70%;

6. The participant must receive treatment with Riluzole (50 mg twice daily) for ≥30 days prior to Day 1 (Visit 2) and is expected to remain on that dose until the final study visit.

7. Willingness and ability of the patient to comply with the requirements of the protocol during the study;

8. Sign written informed consent prior to any study-related procedure;

9. Acceptance by women to use at least one highly effective method of contraception during the study 30 days prior to taking the nutraceutical and investigational drug and throughout the study. The following are considered highly effective contraceptive methods:

   • Combined hormonal methods (oral, patches, injectables, or implants).
   • Hormonal or copper intrauterine devices (IUDs).
   • Previous surgical sterilization (bilateral tubal ligation).
   • Total sexual abstinence when consistent with the patient's usual lifestyle.

10. Acceptance by men included in the study of the use of condoms in combination with an effective contraceptive method used by their female partner of childbearing age during treatment.

Exclusion Criteria:

1. Presence of other neurodegenerative diseases;
2. Significant cognitive impairment and/or dementia;
3. Any psychiatric illness that could interfere with the study;
4. Use of dietary supplements with high doses of vitamin B3 in the 30 days prior to inclusion in the study;
5. Severe heart disease;
6. Moderate to severe lung disease, such as emphysema, stage III-IV COPD;
7. Uncontrolled chronic asthma;
8. Active cancer;
9. Any metabolic, neoplastic, physically or mentally debilitating disease that could put the subject at risk or interfere with the study results;
10. Genetically confirmed mitochondrial disease;
11. Tracheostomized and/or gastrostomized patients;
12. Participation in any clinical trial with an investigational product within 30 days or five half-lives of the previous agent, whichever is longer, prior to dosing;
13. Any clinically significant laboratory abnormality that could directly affect compliance or safety;
14. Allergy to NAC or any excipient, either in the investigational drug or in the EH301 nutraceutical;
15. Patients with a short life expectancy in the investigator's judgment.
16. [Women only] Pregnancy or breastfeeding for women of childbearing potential (i.e., <2 years postmenopausal or not surgically sterile);
17. The participant is unwilling to use highly effective contraception during the study.

Pharmacy team