This study will compare two different formulations of vabicaserin.

Inclusion Criteria:

• Sexually active men must agree to use a medically acceptable form of contraception during the study and continue it for 12 weeks after investigational product administration.
• Nonsmoker or smoker of fewer than 10 cigarettes per day as determined by history. Must be able to abstain from smoking during the inpatient stay.

Exclusion Criteria:

• Use of any investigational or prescription drug within 30 days before investigation product administration.
• Consumption of any caffeine-containing products (eg, coffee, tea, chocolate, or soda) or alcoholic beverages within 48 hours before study day 1.
• Use of any over-the-counter drugs, including herbal supplements within 72 hours before study day 1.