Amitriptyline HCl is an inhibitor of both serotonin transporter (SERT) and norepinephrine transporter (NET) with Ki of 3.45 nM and 13.3 nM, respectively. Amitriptyline HCl also inhibits histamine receptor H1, histamine receptor H4, 5-HT2 and sigma 1 receptor with Ki of 0.5 nM, 7.31 nM, 235 nM and 287 nM, respectively. Amitriptyline is a tricyclic antidepressant (TCA).