A Phase I Study of NS-079 in Healthy Participants

Inclusion Criteria 1. Healthy males or females aged 18-55 years (inclusive), with a body mass index (BMI) between 18.00 and 32.00 kg/m2(inclusive) at screening. 2. Not participated in any other clinical trials and received an investigational drug or device within the past 30 days or 5 half-lives prior to screening, whichever is longer. 3. Women of non-childbearing potential (WONCBP) (as defined in Appendix 1); women of childbearing potential (WOCBP) who are abstinent from heterosexual intercourse as a preferred and usual lifestyle choice, or who agree to use highly effective contraception (as defined in Appendix 1) in combination with a condom from the time of signing the informed consent form until at least 90 days after the last dose of investigational product, agree to refrain from ova donation during this period, and return a negative pregnancy test at screening and baseline (Day -1). 4. Surgically sterile males (with verbal confirmation of the absence of sperm in the ejaculate); males who are abstinent from heterosexual intercourse as a preferred and usual lifestyle choice, or who agree to use highly effective contraception with a female partner (as defined in Appendix 1) in combination with a condom from the time of signing the informed consent form until at least 90 days after the last dose of investigational product, and agree to refrain from sperm donation during this period. 5. In good health, determined by the investigator/delegate on the basis of medical history, physical examinations, vital signs, electrocardiograms (ECGs), clinical laboratory tests (hematology, coagulation, urinalysis, blood biochemistry). Repeated examination is allowed once per timepoint at the investigator/delegate's discretion. 6. Full understanding of the purpose, nature, procedures of the study, and the potential adverse reactions. Participant voluntarily participates and signs the informed consent form before any study procedures begin. 7. Agree to provide a biological sample (blood or saliva/buccal swab, per site capability) for Cytochrome P450 2D6 (CYP2D6) pharmacogenetic genotyping during the screening period, and the genotyping results must be available prior to randomization and dosing. 8. Participants must be confirmed CYP2D6 Normal Metabolizers (NM) or Intermediate Metabolizers (IM) based on pharmacogenetic genotyping. For Part 3 \[DDI\] participants only: Must have a confirmed CYP2D6 NM status based on pharmacogenetic genotyping. Exclusion Criteria 1. Known hypersensitivity or allergy to the investigational product, its excipients, or any of its components, or a history of clinically significant allergic reactions that, in the opinion of the investigator/delegate, may place the participant at increased risk. 2. Known hypersensitivity to or severe intolerance of paroxetine or any SSRI (including serotonin syndrome or discontinuation syndrome) (for Part 3 \[DDI\] only). 3. Unable to refrain from all known CYP2D6 substrate medications (including over-the-counter (OTC) medications such as dextromethorphan-containing cough and cold preparations) during paroxetine dosing (for Part 3 \[DDI\] only). Final clinical judgment on individual concomitant medications remains with the investigator/delegate. 4. Individuals with a history of intolerance to venipuncture or venous catheterization (e.g., recurrent syncope during blood draws or significant needle phobia) that, in the opinion of the investigator/delegate, may interfere with the study procedures. 5. Positive serologic test results for hepatitis B surface antigen (HBsAg), hepatitis C virus antibody (Anti-HCV) or human immunodeficiency virus antibody (Anti-HIV) at Screening. 6. Average daily smoking of more than 5 cigarettes per day in the 3 months prior to Screening, or inability or unwillingness to abstain from the use of tobacco or nicotine-containing products (including cigarettes, e-cigarettes, vaping products, and nicotine replacement products) from 48 hours prior to the first dose through completion of the final safety follow-up visit. 7. Excessive alcohol consumption, defined as average weekly alcohol intake exceeding 14 units during the 4 weeks prior to Screening (1 unit ≈10 g of pure alcohol; 1 alcohol unit is equal to 375ml 3.5% beer, 100 mL of wine, or 30 mL of 40% spirit), unwillingness or inability to abstain from alcohol and alcohol-containing products from 48 hours prior to the first dose through the completion of the final safety follow-up visit, or a positive alcohol breath test at Screening or upon admission to the clinical unit. (A repeat test may be performed once per timepoint at the investigator/delegate's discretion). 8. Excessive consumption of caffeinated beverages (e.g., coffee, tea, energy drinks), defined as an average of \>8 cups/day (1 cup ≈ 250 mL) within 3 months prior to screening, or unwillingness or inability to refrain from caffeinated beverages from 48 hours prior to the first dose through the end of the inpatient confinement phase. 9. Unwillingness or inability to abstain from grapefruit or grapefruit containing products, Seville (bitter) oranges, or pomelo/pomelo-containing products from 7 days prior to the first dose through the end of the inpatient confinement phase. 10. Use of classic psychedelics or hallucinogenic substances with primary 5-HT2A agonist activity (e.g., lysergic acid diethylamide \[LSD\], psilocybin/magic mushrooms, dimethyltryptamine \[DMT\], ayahuasca, mescaline) on 5 or more occasions lifetime, or any use within 5 years prior to Screening. 11. Current or past substance use disorder (including alcohol or drugs of abuse) within the 12 months prior to Screening, as judged by the investigator/delegate; use of ketamine or phencyclidine (PCP) for recreational or non-prescribed purposes within 12 months prior to Screening; use of cannabis within 6 weeks prior to Screening; use of other illicit drugs or non-prescribed psychoactive substances (including but not limited to MDMA, cocaine, opiates,