3. Concomitant use of vasoconstricting agents such as ephedrine, dihydroergotamine, or midodrine. Concomitant use of other noradrenergic medications, such as serotonin-norepinephrine reuptake inhibitors (SNRI's) is also contraindicated. Patients must stop taking these drugs at least 2 days or 5 half-lives (whichever is longer) prior to their baseline visit and throughout the duration of the study.