The present invention provides pharmaceutical compositions comprising droxidopaalone, or in combination with one or more further active ingredients, for thetreatment of conditions, such as mood disorders, sleep disorders, or attentiondeficit disorders. In certain embodiments, the compositions useful in the methodsof the invention comprise droxidopa and a compound selected from the group consistingof DOPA decarboxylase inhibiting compounds, catechol-0-methyltransferaseinhibiting compounds, cholinesterase inhibiting compounds, monoamine oxidaseinhibiting compounds, norepinephrine reuptake inhibiting compounds, selectiveserotonin reuptake inhibiting compounds, tricyclic antidepressant compounds,serotonin norepinephrine reuptake inhibiting compounds, norepinephrinedopamine reuptake inhibiting compound, noradrenergic and specific serotonergicantidepressants, and combinations thereof. The inventive compositions areparticularly useful in the treatment of depression, narcolepsy, insomnia,and Attention Deficit/Hyperactivity Disorder (AD/HD).
