The primary objective of this study is to assess the safety and tolerability of a single day dosing and a separate multiple day dosing of 18-MC HCl administered orally, each part of the study having a different set of healthy male and female volunteers.

This is a Phase 1, double-blind, randomized, placebo-controlled, single day and multiple day dosing, in healthy, non-smoking, male and female volunteers.

Part 1: Single Ascending Dose (SAD)

Seven (7) healthy male and female volunteers will be randomly assigned to receive either 18-MC HCl (n=5) or placebo (n=2) in each cohort. These volunteers will receive 18-MC HCl twice in 1 day (bid).

There are 3 phases: Screening, Enrollment and Follow-Up. All participants will be assessed for safety and tolerability for 28 days. Screening begins when a participant reports to the clinical unit (CU) for a screening visit to undergo safety and compliance assessments on this day. Participants that meet all eligibility criteria will be admitted to the CU on the day prior to receiving study drug. Enrollment begins on Day 1 where participants will receive two doses of study drug for 1 day, will be assessed for 18-MC PK up to 48 hours, and will remain admitted at the CU until Day 3, at which time they will be discharged. For follow-up the participants will return for safety and tolerability assessments at Days 7, 14, 21 and Day 28.

Part 2: Multiple Day Ascending Dose (MAD)

Seven (7) healthy male and female volunteers will be randomly assigned to receive either 18-MC HCl (n=5) or placebo (n=2) in each cohort. These volunteers will receive 18-MC HCl twice over 7 days (bid).

There are 3 phases: Screening, Enrollment and Follow-Up. All participants will be assessed for 42 days. Screening begins when a participant reports to the clinical unit (CU) for a screening visit to undergo safety and compliance assessments on this day. Participants that meet all eligibility criteria will be admitted to the CU on the day prior to receiving study drug. Enrollment begins on Day 1 where participants will receive two doses of study drug every day for 7 days, will be assessed for 18-MC PK up to 48 hours on Day 1 and Day 7, and will remain admitted at the CU until Day 9, at which time they will be discharged. For follow-up the participants will return for safety and tolerability assessments at Days 14, 21, 28, 35 and Day 42.

Key Inclusion Criteria:

1. Written informed consent before any study-specific procedures.
2. Healthy male and female volunteers aged 18 to 55 years (inclusive) with suitable veins for cannulation and repeated venipuncture.
3. Female subjects of both childbearing and nonchildbearing potential will be considered, with certain conditions met
4. Female subjects must agree not to breastfeed starting at screening and throughout the study period.
5. Male participants must agree to practice abstinence; be surgically sterilized; or agree to use of a condom, plus effective contraception.
6. Have not smoked or used any tobacco or nicotine-containing products in the 3 months before screening and agree not to smoke during the entire study.

Key Exclusion Criteria:

1. History of any clinically important disease or disorder that, in the opinion of the investigator, would affect the ability of the participant to participate in the study
2. History or presence of gastrointestinal, hepatic, cardiac, or renal disease or any other condition known to interfere with absorption, distribution, metabolism, or excretion of study drug.
3. History of gastrointestinal ulcer disease, inflammatory bowel disease, or frequent indigestion symptoms
4. Adequate organ function
5. History of seizures or epilepsy.
6. Any positive result on screening for serum hepatitis B surface antigen, hepatitis C antibody, and human immunodeficiency virus (HIV).
7. Any clinically significant cardiovascular abnormalities
8. Known or suspected history of substance abuse disorder
9. History of alcohol abuse or excessive intake of alcohol
10. Positive screen for drugs of abuse, cotinine (nicotine) or alcohol
11. Has received another new chemical entity (defined as a compound, which has not been approved for marketing) or has participated in any other clinical study that included drug treatment within 30 days