Approximately 9 participants will be enrolled in the study in a single cohort. Participants will be randomized to 3 g IXT-m200 or placebo at 7:2. Each will receive their dose as a 30-min intravenous infusion, then remain at the study site overnight to complete Day 1 and Day 2 assessments (e.g., electrocardiogram (ECG), laboratory assessments, blood draws, and vital signs). Following discharge on Day 2, participants will return to the clinic for follow-up pharmacokinetic (PK) and safety assessments on Day 8, then every 1-3 weeks thereafter until Day 127.

Inclusion Criteria:

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Eligible participants will:

1. Be 18-65 years of age, inclusive, at the time of study consent;
2. Be able and willing to read, comprehend, and give Authorization for Use/Disclosure of Health Information (HIPAA) and informed consent;
3. Be healthy, based on the pre-study medical evaluation (medical history and physical exam, vital signs, ECG, and clinical laboratory evaluations);
4. Be willing to comply with study instructions and dosing, agree to make all appointments, and complete the entire course of the study;
5. Be of nonchildbearing potential or agree to use protocol-specified method(s) of birth control throughout study participation;
6. Agree to adhere to Lifestyle Considerations throughout study duration.

Exclusion Criteria:

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Eligible participants will NOT:

1. Have a history of treatment with a monoclonal antibody in the past year;
2. Have a known contraindication or sensitivity to IXT-m200 based on known allergies to other mAbs, any inactive ingredient of IXT-m200, or any other products required for the study procedures;
3. Have a history of alcohol and/or drug use disorder, as determined by DSM-5 criteria;
4. Have a history of stimulant use, including methamphetamine and amphetamine;
5. Be currently taking certain other drugs and medications, including: "designer drugs" (e.g., 3,4-methylenedioxyMETH (MDMA, Ecstasy, Adam, XTC) and its N-dimethyl metabolite methylenedioxyamphetamine (MDA), anti-orexigenic drugs (including over-the-counter medications for weight loss), or be chronic users of phenethylamine compounds (e.g., phenylpropanolamine, ephedrine, pseudoephedrine, amphetamine, phentermine, phenmetrazine, methylphenidate, diethylpropion, and propylhexedrine);
6. Have a positive drug screen for any psychoactive substances (legal or nonlegal) on Day 1 prior to dosing;
7. Have a history of severe allergy (rash, hives, breathing difficulty, etc) to any medications;
8. Have a history of allergic or environmental bronchial asthma within the past 3 years;
9. Have a clinically significant history of or current abnormality or disease of any organ system, including renal, hepatic, gastrointestinal, cardiovascular, pulmonary (including chronic asthma), endocrine (eg, diabetes), central nervous (eg psychiatric conditions), or hematologic systems, or recent clinically significant surgery;
10. Have a history of seizure, epilepsy, severe head injury, multiple sclerosis, or other known neurological conditions;
11. Have a planned or scheduled surgical procedure during the study;
12. Have recently donated blood or plasma (within 30 days of study drug dose);
13. Have a current diagnosis of anorexia nervosa or bulimia disorder;
14. Be currently participating or has participated within the last 30 days prior to the start of this study in a drug, device, or other interventional research study;
15. Be pregnant or lactating;
16. In the Investigator's or Sponsor's (or designee) opinion, be inappropriate for the study.

Final datasets are expected to contain pharmacokinetic data on IXT-m200 and safety data. No individually identifiable private information will be distributed.

These datasets will be available for distribution following submission to the FDA of the Clinical Study Report and publication. They will be available for 2 years after the initial publication.

These datasets and associated documentation will be made available on CD by the Sponsor to requestors under a data sharing agreement that provides for: (1) a commitment to using the data only for research purposes; (2) a commitment to securing the data using appropriate computer technology and not distributing to third parties; and (3) a commitment to destroying or returning the data after analyses are completed. Requests should be sent to intervexion@gmail.com.

Baseline assessments were conducted at the screening visit or on Day 1.

Adverse event data were collected following the start of administration of study drug on Day 1 through the final study visit on Day 127.

AE data were collected at study visits or between visits if participants informed the site by phone or visit.