Citalopram (Celexa) Medication Class
Citalopram (Celexa) is a selective serotonin reuptake inhibitor (SSRI), a class of antidepressant medications that specifically inhibit serotonin reuptake in the central nervous system. 1, 2
Pharmacological Classification and Mechanism
Citalopram belongs to the SSRI class of medications, which:
- Acts by selectively blocking serotonin reuptake in presynaptic neurons
- Has a chemical structure unrelated to tricyclic antidepressants or other antidepressant agents
- Is a racemic bicyclic phthalane derivative 1
- Is considered one of the most selective serotonin antidepressants available 3
Clinical Applications
Citalopram is primarily used for:
- Major depressive disorder
- Anxiety disorders
- Obsessive-compulsive disorder
- Panic disorder
- Post-traumatic stress disorder
- Eating disorders 2, 4
Additional off-label uses include:
- Premenstrual dysphoria
- Alcohol dependence
- Behavioral disturbances in dementia 4
Pharmacokinetic Properties
- Elimination half-life of approximately 33 hours, allowing for once-daily dosing 5
- Metabolized predominantly via oxidation by cytochrome P450 enzymes in the liver
- Partially metabolized via the mephenytoin oxidation pathway 6
Safety Considerations
QT Prolongation Risk
Citalopram carries a dose-dependent risk of QT interval prolongation:
- Maximum recommended dose is 40 mg/day due to QT prolongation risk
- For patients over 60 years old, maximum dose is limited to 20 mg/day
- Also limited to 20 mg/day in CYP2C19 poor metabolizers, patients taking CYP2C19 inhibitors, and those with hepatic impairment 1, 2
Contraindications
Citalopram should not be used in patients with:
- Congenital long QT syndrome
- Bradycardia
- Hypokalemia or hypomagnesemia
- Recent acute myocardial infarction
- Uncompensated heart failure
- Concurrent use of other QT-prolonging medications 1
Adverse Effects
Common side effects include:
- Nausea (most frequent, occurring in about 20% of patients)
- Increased perspiration
- Headache
- Dry mouth
- Tremor
- Insomnia (15-18% of patients)
- Sexual dysfunction 5, 2
Comparison to Other Antidepressants
- Better tolerated than tricyclic antidepressants with fewer anticholinergic and cardiovascular side effects 5
- Similar efficacy to other SSRIs but with a more favorable drug interaction profile than some (particularly paroxetine and fluoxetine) 6
- Unlike tricyclic antidepressants, citalopram has minimal anticholinergic effects and does not appear to be cardiotoxic at therapeutic doses 5
Special Populations
Pregnancy and Breastfeeding
- SSRIs including citalopram have been associated with neonatal complications when used in late pregnancy
- Potential adverse effects in breastfed infants include irritability and decreased feeding 2
- Citalopram transfers in low concentrations into breast milk 2
Elderly Patients
- Maximum dose should be limited to 20 mg/day in patients over 60 years due to higher exposure levels and increased risk of QT prolongation 1
In summary, citalopram is an SSRI antidepressant with high selectivity for serotonin reuptake inhibition, offering efficacy comparable to other antidepressants with a generally favorable side effect profile, though requiring dose limitations due to QT prolongation risk.