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.