This study is a single-center, randomized, open-label, active and placebo-controlled, parallel-group, conducted in healthy male volunteers who have been shown to be extensive metabolizers of dextromethorphan.

Inclusion Criteria:

1. Healthy males between the ages of 18 and 55
2. Non-Smokers
3. Body weight range form 154-220 lbs
4. No history of clinically significant metabolic disorders.

Exclusion Criteria:

1. Any history of low CYP450 2D6 activity
2. History of alcohol abuse or recreational drugs
3. History of any clinically significant disease or condition affecting a major organ system
4. Donation or loss of blood, 60 days proceeding to screening visit.