Multiple-Dose Study to Evaluate the Safety and Efficacy of IXT-m200

Eligible participants will: 1. Be at least 18 years of age at the time of study consent; 2. Meet Diagnostic and Statistical Manual of Mental Disorders (DSM)-5 criteria for Substance Use Disorder associated with methamphetamine; 3. Be treatment-seeking methamphetamine users with at least 1 methamphetamine or amphetamine positive specimen during the screening period; 4. Be able and willing to read, comprehend, and give Authorization for Use/Disclosure of Health Information (HIPAA) and informed consent; 5. Be willing to comply with study instructions and dosing, agree to make all appointments, and complete the entire course of the study; 6. Agree to use protocol-specified method(s) of birth control throughout study participation; 7. Agree to adhere to Lifestyle Considerations throughout study duration; 8. Have access to a smartphone or other device capable of supporting the study app; 9. Successfully complete app-based training program as evidenced by completion of at least 75% of daily drug use surveys and assigned saliva drug screens (two of which must be valid) in ≤30 days from the screening visit during the screening period. Eligible participants will NOT: 1. Have current dependence, defined by DSM-5 criteria, on any psychoactive substance (i.e., opioids or benzodiazepines), other than methamphetamine or nicotine (any severity). Mild severity dependence on alcohol or marijuana is allowed; 2. 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); 3. Have a known contraindication or sensitivity to IXT-m200 based on known allergies to other monoclonal antibodies, any inactive ingredient of IXT-m200, or any other products required for the study procedures; 4. Have a history of severe allergy (rash, hives, breathing difficulty, etc) to any medications; 5. Have a history of allergic or environmental bronchial asthma within the past 3 years; 6. Have a current diagnosis of anorexia nervosa or bulimia disorder; 7. Have a history of unstable cardiovascular disease that is not adequately controlled at the time of eligibility determination; 8. Be mandated by the court to obtain treatment for methamphetamine-dependence where such mandate required the results of methamphetamine testing to be reported to the court; 9. Have positive saliva drug screens for psychoactive substances other than amphetamines at the screening visit; 10. Be expected to fail to complete the study protocol due to probable incarceration or relocation from the clinic area, or any clinically significant mental or physical illness within a 1-year prior, that would impact compliance with trial requirements; 11. Have clinically significant laboratory values (outside of normal limits). The following specified ranges are allowable: 1. Liver function tests (total, direct, and indirect bilirubin, aspartate transaminase, alanine aminotransferase, gamma-glutamyl transferase, lactate dehydrogenase, and alkaline phosphatase) \<3 times the upper limit of normal, and 2. Kidney function tests (creatinine and BUN) \<2 times the upper limit of normal; 12. Be considered to be at imminent risk of suicide or have a past-year history of a serious suicide attempt (defined as an attempt that results in or requires medical treatment) based on response to queries within eligibility screening about suicidal ideation and attempts; 13. Have an uncontrolled systemic disease or a medical condition that may increase the risk associated with study participation or administration of study treatment or that may interfere with the interpretation of study results; 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, including those believed to be attempting to enter the study primarily for financial gain.