This study will evaluate the potential for a drug-drug interaction of Dimebon with ketoconazole and omeprazole, potent inhibitors of the drug metabolizing enzymes CYP3A4 and CYP2C19, respectively.

Inclusion Criteria:

• Subjects who are willing and able to comply with scheduled visits, treatment plan, laboratory tests, and other study procedures.
• Subjects must have either a CYP2D6 EM (n=12) or PM (n=12) status based on genotyping at screening.
• Subjects must have a CYP2C19 EM status based on status at screening.

Exclusion Criteria:

• Evidence or history of clinically significant hematological, renal, endocrine, pulmonary, gastrointestinal, cardiovascular, hepatic, psychiatric, neurologic, or allergic disease.
• Subjects with any history of a previous seizure or convulsion or significant head trauma.
• Subjects specifically allergic to imidazole antifungal agents.
• Subjects specifically allergic to omeprazole or other proton pump inhibitors.
• Any condition possibly affecting drug absorption (eg, gastrectomy).
• Subjects with hypersensitivity reactions to Dimebon or other antihistamines.
• Consumption of grapefruit or grapefruit containing products within 7 days prior to the first dose of study medication.
• Subjects currently taking omeprazole, other proton pump inhibitors, antacids, H2-blockers or CYP2C19 inhibitors.
• Pregnant or nursing females; females of childbearing potential who are unwilling or unable to use an acceptable method of nonhormonal contraception as outlined in this protocol from at least 14 days prior to the first dose of study medication.