This is a study of EMB-001 (a combination of two FDA-approved drugs, metyrapone and oxazepam) in otherwise healthy adults who are regular cigarette smokers. There will be 3 groups of 8 subjects; in each group, 6 subjects will get the drug combination and 2 will get placebo. Neither the subjects nor the study personnel will know who got drug and who got placebo (double-blind). In the first group the drug doses will be low, and they will be increased in the second and third groups. Subjects will receive a single dose on Day 1, followed 24 hours later by the start of doses twice daily for 7 days, and then a final morning dose on the last day. The levels of the drugs in the blood will be assessed by repeated blood draws after the first day and after the end of dosing. Safety will be assessed after the single dose and repeated dosing. Effects of study drug on smoking and craving cigarettes will be assessed at the end of repeated dosing. The hypothesis is that this drug combination will be safe, with relatively few side effects.

This study is a Phase 1, double blind, single and multiple rising dose tolerance study of EMB-001 (metyrapone/oxazepam combination) in otherwise healthy adults who have tobacco use disorder. There will be 3 cohorts, each with 8 subjects (6 active: 2 placebo), for a total of 24 subjects. During the treatment period, subjects will receive a single dose of EMB 001 on Day 1, followed 24 hours later by the start of multiple doses twice daily for 7 days, and then a final morning dose on the last dosing day (Day 9). This design allows for characterization of EMB-001 single dose PK for 24 hours, followed by assessment of repeat dose PK in the multiple-dose phase. Safety will be assessed after the single dose and repeated dosing. Effects of study drug on smoking and craving cigarettes will be assessed at the end of repeated dosing. Later studies may also assess the efficacy of this drug combination in treating cocaine use disorder, tobacco use disorder, and/or other disorders.

Inclusion Criteria:

• Males and females of Non-Childbearing Potential age 18-65
• Have provided written informed consent prior to any study procedures
• Are willing and able to comply with all aspects of the protocol
• Normal or clinically acceptable screening electrocardiogram (ECG)
• Normal blood pressure (systolic: 90-140 mmHg; diastolic 50-90 mmHg) and heart rate (50-100 bpm)
• Smoke at least 10 cigarettes per day (for approximately 1 year or longer)
• Body mass index > 18.5 and < 35

Exclusion Criteria:

• Known hypersensitivity to or intolerance of oxazepam or metyrapone, or any benzodiazepine
• Subjects with a low out-of-range serum cortisol value at screening or subjects who, in the investigator's opinion, have a heightened likelihood of having adrenal insufficiency.
• Subjects who have a positive urine drug screen for illegal drugs or other drugs with a high potential for abuse (other than nicotine).
• Inability to communicate or cooperate with the investigator
• History of drug dependence (except nicotine) or psychiatric illness within the past 2 years.
• Subjects with any history of adrenal insufficiency or other adrenal, hypothalamic, or pituitary disorders.
• History of asthma or other respiratory disease, neurologic or neuromuscular disease, or hypotension or cardiovascular disease, that may, in the opinion of the investigator, impact any study procedures or measures, or compromise the safety of the subject.
• Other severe, acute, or chronic medical or psychiatric condition or laboratory abnormality that may increase the risk associated with trial participation or investigational product administration or may interfere with the interpretation of trial results and, in the judgment of the Investigator or Sponsor, would make the subject inappropriate for entry into this trial.