20 mg dimebon by mouth 3 times per day

20 mg placebo by mouth 3 times per day

Treatment discontinuation due to adverse events, the frequency and severity of adverse events, and clinically significant changes in safety assessments (including physical examination findings, vital signs, laboratory values, and ECGs) in the dimebon group will be compared to those reported in the placebo group.

The following key parameters will be used to assess the steady-state PK of dimebon: maximum plasma concentration (Cmax), time to maximum plasma concentration (tmax), Ctrough, area under the curve (AUC), and peak-to-trough ratio.