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Drug Reference

citalopram

Selective serotonin reuptake inhibitor (SSRI)· Brands: Celexa, Cipramil, SeropramPO

Mechanism of action
Citalopram is a selective serotonin reuptake inhibitor. It binds to the serotonin transporter and blocks the reuptake of serotonin into presynaptic neurons, increasing serotonin availability in the synaptic cleft. At therapeutic doses it has negligible affinity for other receptors such as adrenergic, dopaminergic, histaminergic, or muscarinic receptors.
Pharmacokinetics
Citalopram is well absorbed after oral administration, with peak plasma concentrations occurring 2 to 4 hours after dosing. Bioavailability is about 80%. It is extensively metabolised in the liver via CYP2C19 and CYP3A4 to active metabolites, but the parent drug is primarily responsible for the antidepressant effect. Elimination is predominantly renal; the half-life is approximately 36 hours. Dose reduction is suggested in elderly patients and those with hepatic impairment.
Indications & dosing

Major depressive disorder

Start at 20 mg once daily; increase if necessary after at least 1 week. Maximum 40 mg daily due to risk of QT prolongation.

  • adult · PO: 20–40 mg once daily · Start at 20 mg once daily; increase if necessary after at least 1 week. Maximum 40 mg daily due to risk of QT prolongation.

Panic disorder

Initial 10 mg once daily for 1 week, then increase to 20 mg. Usual maintenance 20-30 mg. Maximum 40 mg daily.

  • adult · PO: 10–40 mg once daily · Initial 10 mg once daily for 1 week, then increase to 20 mg. Usual maintenance 20-30 mg. Maximum 40 mg daily.

Major depressive disorder (elderly)

Start at 10 mg once daily; maximum 20 mg daily in patients over 65 years.

  • elderly · PO: 10–20 mg once daily · Start at 10 mg once daily; maximum 20 mg daily in patients over 65 years.
Contraindications & precautions
  • Concomitant use with MAOIs · Wait at least 14 days after stopping an MAOI before starting citalopram, and at least 5 days after stopping citalopram before starting an MAOI.
  • Known QT prolongation or congenital long QT syndrome · Citalopram can prolong the QT interval and increase the risk of torsades de pointes.
  • Hypersensitivity to citalopram · Cross-reactivity with other SSRIs possible.
  • Concomitant use with pimozide · Additive QT-prolonging effect; contraindicated.
  • Use with caution in patients with epilepsy or a history of seizures; citalopram may lower the seizure threshold.
  • Monitor for signs of serotonin syndrome, especially when combined with other serotonergic agents (e.g., tramadol, triptans).
  • Use caution in patients with risk factors for QT prolongation, such as hypokalaemia, hypomagnesaemia, or taking other QT-prolonging drugs.
  • Caution in hepatic impairment; consider dose reduction and monitor liver function.
  • Caution in the elderly; maximum dose is reduced (e.g., 20 mg/day in patients over 65 years).
  • Caution in patients with bipolar disorder; monitor for manic switch.
Adverse effects
  • Nausea
  • Headache
  • Dry mouth
  • Somnolence or insomnia
  • QT prolongationserious
  • Hyponatremia (SIADH)serious
  • Abnormal bleedingserious
  • Serotonin syndromeserious
Interactions
  • ibuprofenmoderateWhen citalopram and ibuprofen are co-prescribed, use caution and consider alternative analgesia such as paracetamol if appropriate. If an NSAID is necessary, use the lowest effective dose for the shortest duration, and administer a gastroprotective agent such as a proton pump inhibitor, especially in patients with risk factors. Monitor patients for signs of gastrointestinal bleeding, including black stools, melaena, haematemesis, or unexplained anaemia, and advise them to seek prompt medical attention if these occur.
  • tramadolmajorAvoid the combination where possible. If co-administration is necessary, use the lowest effective doses of both drugs, and prescribe with caution in patients with pre-existing seizure disorders or cardiac disease. Monitor the patient closely for signs of serotonin syndrome (especially during the first few days) and for seizures. Consider alternative analgesics such as paracetamol, NSAIDs, or non-serotonergic opioids (e.g., oxycodone, morphine) if appropriate. If citalopram dose exceeds 40 mg/day, reassess the need for tramadol. Advise patients to seek immediate medical attention if they develop symptoms such as confusion, muscle twitching, or increased sweating. An ECG may be warranted if there are other risk factors for QT prolongation.
  • aspirinmajorAssess the need for aspirin and citalopram co-prescription. If aspirin is required for cardiovascular protection, consider gastroprotective measures such as a proton pump inhibitor. Use the lowest effective doses of each drug. Monitor for signs of gastrointestinal bleeding (e.g., black stools, anaemia) and evaluate haemoglobin periodically. Consider alternative analgesia or anticoagulation strategies where appropriate, and avoid concurrent use in high-risk patients unless benefits clearly outweigh risks.
Renal & hepatic adjustment
  • eGFR 0–20: Use with caution; maximum dose 20 mg daily.
  • Hepatic impairment (mild): Maximum dose 20 mg daily.
  • Hepatic impairment (moderate): Maximum dose 20 mg daily.
  • Hepatic impairment (severe): Avoid use. (avoid)
Monitoring, pregnancy & toxicity
  • Suicidal ideation and behaviour, especially during initiation and dose changes · At baseline, during first weeks of treatment, and after dose changes
  • Signs of serotonin syndrome (agitation, tremor, hyperreflexia, fever) · Regularly, especially when used with other serotonergic drugs
  • QT interval (ECG) in patients at risk of QT prolongation or with doses > 40 mg/day · At baseline and before dose increases
  • Serum sodium in elderly patients or those on diuretics (risk of SIADH) · At baseline and periodically during treatment
  • Signs of bleeding (e.g., bruising, epistaxis) especially with concurrent anticoagulants · Regularly
  • Pregnancy: Use only if clearly necessary. Evidence suggests low risk of malformations, but there is a risk of neonatal adaptation syndrome if continued to term. Seek specialist advice. Tapering near birth may be considered, but weigh risks of relapse.
  • Toxicity: QT prolongation and arrhythmias · Monitor ECG, correct electrolytes, avoid other QT-prolonging drugs. Consider activated charcoal if recent ingestion. In severe cases, seek specialist advice.
  • Toxicity: Serotonin syndrome (agitation, confusion, hyperreflexia, fever) · Supportive care, benzodiazepines, cyproheptadine if severe. Discontinue citalopram and serotonergic drugs.
  • Toxicity: Seizures · Supportive care, intravenous benzodiazepines, monitor airway.
  • Toxicity: Nausea, vomiting, dizziness, tremor · Symptomatic supportive care, ensure hydration.
Clinical notes
It may also be used off-label for obsessive-compulsive disorder and social anxiety disorder.

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BNF; local formulary