3. Subject has NOT been on tricyclic antidepressants, serotonin, norepinephrine, or mixed serotonin/norepinephrine reuptake inhibitors (SSRI/SNRI), or muscle relaxant with potential action as an SSRI or SNRI (e.g., Flexeril) for at least one month. Subject has not been on monoamine oxidase inhibitors in the past 14 days.