28-Day Repeat-Dose, Dose-Escalation Study: Based on the safety and tolerability of the single dose study and serum DMA levels attained, three doses of two formulations of DMAU were selected for a dose-escalating 28-day repeat dose study. Safety will be assessed in subjects receiving lower dosages before additional men receive higher doses for 28 days. Up to 100 men will be randomized to receive either active drug or an identical number of capsules of placebo. The 24-hour detailed PK of DMA will be assessed on day 1 and 28. Trough levels of DMA will be obtained throughout the 28-day period and at 48 and 72 hours after the last dose. In addition to safety and tolerability, suppression of serum T, gonadotropins, and SHBG will also be assessed as secondary pharmacodynamic (PD) endpoints. Psychosexual diaries for 7 consecutive days and PHQ-9 (questionnaire)will be obtained before and at the end of the study period.