Citalopram is an antidepressant sold under the trade names Celexa® and Cipramil for the treatment of major depression.

Citalopram is a selective serotonin reuptake inhibitor, a class of drugs that also includes fluoxetine, paroxetine, and sertraline. This internal standard is suitable for quantitation of citalopram levels in urine, serum, or plasma by LC/MS or GC/MS for urine drug testing, clinical toxicology, forensic analysis, or isotope dilution methods.