Esmirtazapine
Esmirtazapine, known by the standardized identifier SCH 900265, was under development by Organon to treat insomnia and vasomotor symptoms associated with menopause. Esmirtazapine is the (S)-(+)-enantiomer of mirtazapine and possesses similar overall pharmacology. This includes inverse agonist activity of H1 and 5-HT2 receptors and antagonism of α2-adrenergic receptors. Merck has terminated its internal clinical development program for esmirtazapine as of March 2010.