Flerobuterol, also known as CRL-40996, is a β adrenergic receptor agonist potentially for the treatment of major depressive disorder. Flerobuterol enhances serotonergic neurotransmission: an electrophysiological study in the rat brain. Flerobuterol, similar to other beta-adrenergic agonists, acutely increases 5-HT synthesis, in part, through an elevation of brain Trp availability.