Escitalopram vs Citalopram: what is the difference?

How they differ

Citalopram is a mixture of two mirror-image forms of the same molecule and escitalopram is the active one isolated. The inactive half does not simply sit there: it appears to blunt the active half slightly, which is the argument for separating them. Everything else is identical, same formula C20H21FN2O, same weight of 324.4, same serotonin transporter. Half the amount of escitalopram does roughly what a full amount of citalopram does, which is why the numbers on the two prescriptions look different for what is chemically the same substance. Citalopram carries a stronger warning about heart rhythm at higher amounts than escitalopram does.

Side by side

Structural similarity 1.00 of 1, computed as a Morgan fingerprint Tanimoto coefficient. It measures shape, not effect.

Common questions

What is the difference between Escitalopram and Citalopram?

Citalopram is a mixture of two mirror-image forms of the same molecule and escitalopram is the active one isolated. The inactive half does not simply sit there: it appears to blunt the active half slightly, which is the argument for separating them. Everything else is identical, same formula C20H21FN2O, same weight of 324.4, same serotonin transporter.

Do Escitalopram and Citalopram have the same formula?

Yes. Both are C20H21FN2O at 324.4 g/mol. They are isomers: the same atoms arranged differently, which is why they behave differently despite weighing the same.