Amitriptyline is an orally active tricyclic antidepressant (TCA). Amitriptyline mainly exerts its antidepressant effect by blocking SERT (Ki = 3.45 nM) and NET (Ki = 13.3 nM), thereby increasing the concentrations of 5-hydroxytryptamine (5-HT) and norepinephrine (NE) in the synaptic cleft. Amitriptyline is also an agonist at alpha2A and TrkA/TrkB receptors, thereby exerting analgesic and neurotrophic activities (inhibiting cell apoptosis). Amitriptyline can reduce inflammation, angiogenesis and fibrosis. Amitriptyline binds to DAT (with Ki = 2.58 µM). Amitriptyline has high affinity for a series of receptors and can antagonize muscarinic cholinergic receptors (M1/M2/M3/M4/M5 receptors) (Ki = 11-24 nM), H1 receptors (Ki = 0.5-1.1 nM), adrenergic alpha1 receptors (Ki = 4.4 nM), etc., resulting in a series of side effects. Amitriptyline can block sodium channels and hERG potassium channel (IC50 = 4.78 µM) and it has cardiotoxicity[1][2][3][4][5].
