Citalopram
Citalopram is a widely prescribed SSRI for major depressive disorder and anxiety, marketed as Celexa and Cipramil. It is the racemic mixture from which escitalopram (the more active S-enantiomer) was developed; modern dosing is capped at 40mg daily because of dose-related QT prolongation.
- Chemical formula
- C20H21FN2O
- CAS number
- 59729-33-8
- ATC code
- N06AB04
- Molecular weight
- 324.39 g/mol
- Drug class
- Selective serotonin reuptake inhibitor (SSRI)
- Also known as
- Celexa, Cipramil, Seropram
What is it?
Citalopram is an SSRI antidepressant approved by the FDA in 1998 and marketed as Celexa (US) and Cipramil (Europe/UK), with widely available authorised generics. It is the racemic mixture of two mirror-image enantiomers, of which the S-enantiomer (escitalopram, Lexapro) was later isolated and marketed as a more potent successor. Despite escitalopram's commercial dominance, citalopram remains widely prescribed because of long-standing familiarity, low cost and a well-characterised safety profile.
Mechanism of action
Citalopram selectively inhibits the serotonin reuptake transporter, increasing synaptic serotonin availability with limited affinity for noradrenaline transporters or other receptors. This combination of selectivity and clean off-target profile means citalopram has fewer drug interactions than older antidepressants and a relatively benign side-effect profile. Therapeutic effect develops over 4–6 weeks. Citalopram is the most selective of the SSRIs for SERT over the noradrenaline transporter.
Pharmacokinetics
Citalopram is well absorbed orally with peak plasma at 4 hours. The terminal half-life is ~35 hours, supporting once-daily dosing. Hepatic metabolism is via CYP3A4, CYP2C19 and CYP2D6 — citalopram is not a strong inhibitor of these enzymes, which produces fewer drug interactions than fluoxetine or paroxetine. CYP2C19 polymorphism affects clearance, with poor metabolisers reaching higher levels at standard doses; the 2011 FDA dose limit (40mg/day; 20mg/day in poor metabolisers and over 60) reflects this.
Indications
Citalopram is approved for major depressive disorder. It is widely used off-label for generalised anxiety disorder, panic disorder, social anxiety, post-traumatic stress disorder, obsessive-compulsive disorder and premenstrual dysphoric disorder. According to current depression guidelines, citalopram is one of the first-line SSRIs along with sertraline and escitalopram, with selection based on patient factors and prescriber familiarity.
Safety profile
Common adverse effects include nausea, dry mouth, headache, sexual dysfunction, sleep disturbance and increased sweating. The class concern most specific to citalopram is dose-related QT prolongation: a 2011 FDA safety review limited the maximum dose to 40mg daily (20mg daily for adults over 60 and CYP2C19 poor metabolisers). Concomitant use with other QT-prolonging agents requires caution. Discontinuation syndrome is mild compared with paroxetine because of the relatively long half-life.
Products containing this ingredient
Frequently asked questions
Is citalopram or escitalopram better? ▾
Escitalopram is the active S-enantiomer of citalopram and is approximately twice as potent on a milligram basis (10mg escitalopram ≈ 20mg citalopram). Some studies suggest slightly better efficacy and tolerability with escitalopram, but the difference is small. According to current depression guidelines, both are first-line; choice depends on cost, prescriber familiarity and patient response.
Why is the citalopram dose limited to 40mg? ▾
A 2011 FDA safety review found dose-related QT prolongation at higher doses, especially above 40mg/day. The maximum recommended dose was reduced to 40mg/day (20mg/day in adults over 60 and CYP2C19 poor metabolisers). According to the prescribing information, doses exceeding the limit do not provide additional benefit but increase arrhythmia risk.
Does citalopram have many drug interactions? ▾
Citalopram has fewer drug interactions than fluoxetine or paroxetine because it is a weaker inhibitor of CYP2D6 and CYP3A4. Important interactions include other QT-prolonging agents, MAOIs, linezolid and triptans (serotonin syndrome risk). According to the prescribing information, citalopram is one of the safer SSRIs in patients on multiple medications.
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.