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.