(R)-Citalopram-d4 (oxalate) is deuterium labeled (R)-Citalopram Oxalate. (R)-Citalopram oxalate, a R-(-) enantiomers of Citalopram (HY-121203), is a serotonin reuptake inhibitor. (R)-Citalopram oxalate is at least 20-fold weaker than S-citalopram (HY-14258) as inhibitor of the 5-HT transporter (SERT). (R)-Citalopram oxalate can be used for research of depression[1][2][3].