Quetiapine-d 4 -1 fumarate is deuterated labeled Quetiapine (hemifumarate). Quetiapine hemifumarate is a 5-HT receptors agonist with a pEC 50 of 4.77 for human 5-HT1A receptor. Quetiapine hemifumarate is a dopamine receptor antagonist with a pIC 50 of 6.33 for human D2 receptor. Quetiapine hemifumarate has moderate to high affinity for the human D2 , HT1A , 5-HT2A , 5-HT2C receptor with pK i s of 7.25, 5.74, 7.54, 5.55. Antidepressant and anxiolytic effects.