The purpose of this Phase 1 single ascending dose (SAD) study is to evaluate the safety and tolerability, pharmacokinetics, and pharmacodynamic profile of MSD-001 when administered orally to healthy adult participants.

This is a first in human, prospective, single center, double blind, placebo-controlled, single ascending dose study to investigate the safety, tolerability, pharmacokinetics, and pharmacodynamics of MSD-001. The study will include two parallel parts, Part 1 and Part 2, stratified by CYP2D6 phenotype.

Key Inclusion Criteria:

• Male or female healthy consented participants 18 to 55 years of age
• CYP2D6 phenotype established based on pharmacogenetic testing.
• Free from psychoactive drug use from 4 weeks before dosing and until the last follow up visit.

Key Exclusion Criteria:

• Any current clinically relevant, or history of, acute or chronic diseases inclusive of psychiatric disorders and relevant family history, which could interfere with the participant's safety during the trial, or expose them to undue risk, or which could interfere with the study objectives.
• Moderate to severe congestive heart failure, history of heart surgery, pulmonary hypertension, systemic hypertension (i.e., systolic BP >139 mm hg, diastolic blood pressure > 89 mm hg), pulse rate > 90 bpm, clinically significant ECG abnormality, QTc > 450 msec, myocardial infarction in the past year, or any other active or severe cardiovascular condition.
• Clinically significant personal or familial history of epilepsy, seizures, convulsions, or other seizure disorder (excluding febrile seizures as a child), previous head trauma or other risk factor for seizure.
• Use of any psychedelic drug in the three months prior to planned dosing or the occurrence of persistent psychological effects following the previous use of psychedelic drugs.
• Subject experiences severe anticipatory anxiety or is otherwise considered unfit for study.
• History of moderate or severe illicit substance abuse or dependence, or a positive test result(s) for alcohol and/or drugs of abuse at screening or admission to the clinical unit.
• Subject has received a prior investigational intervention, has had a history of relevant hypersensitivity or allergic reactions, and has donated and/or received any blood or blood products or experienced blood loss, that may interfere with the objectives of the study.
• Subject has a significant negative life event (e.g. loss of a loved one) in the past 6 months.