TAAR1 and major depressive disorder: Solriamfetol (Sunosi), currently available for the treatment of excessive daytime sleepiness associated with narcolepsy and obstructive sleep apnea, entered phase 3 clinical trials for depression in 2024, acting as a dopamine and norepinephrine reuptake inhibitor and trace amine-associated receptor 1 (TAAR1) agonist.