Citalopram

Citalopram is a selective serotonin reuptake inhibitor (SSRI) that works by blocking the serotonin transporter (SERT), preventing reuptake of serotonin from the synaptic cleft and increasing serotonin availability in the brain ^{[1, 3]}.

Citalopram is a racemic mixture of two mirror-image molecules (enantiomers): S-citalopram and R-citalopram. The S-enantiomer (escitalopram) is responsible for virtually all of the serotonin reuptake inhibition, while the R-enantiomer is essentially inactive at the serotonin transporter ^{[1, 3, 4]}.

Among SSRIs, citalopram is considered the most serotonin-selective — it has very little activity at other neurotransmitter receptors (norepinephrine, dopamine, histamine, muscarinic). This selectivity accounts for its relatively clean side effect profile compared to paroxetine or TCAs ^{[1, 3]}.

In the landmark Cipriani network meta-analysis (2018) comparing 21 antidepressants, citalopram was used as the reference comparator due to its well-established efficacy and tolerability profile. Escitalopram was found to be slightly more effective and better tolerated than citalopram ^[4].

The **STAR*D trial** included citalopram as the first-step treatment, providing extensive real-world data on its effectiveness. Approximately 33% of patients achieved remission with citalopram as initial therapy, establishing important benchmarks for antidepressant treatment ^[5].

Weeks 1-2: Start at 20 mg/day. Nausea is the most common early side effect (21%). Headache, drowsiness, and insomnia may occur. Some patients experience transient increased anxiety, which is a class effect of SSRIs ^{[1, 5]}.

Weeks 2-4: Nausea typically improves. Mood improvement may begin. Sexual side effects (decreased libido, delayed orgasm) may emerge. Your doctor may increase to 40 mg if needed ^[1].

Weeks 4-8: Full antidepressant effects usually evident by 4-6 weeks. In the STAR*D trial, 33% of patients achieved remission with citalopram alone ^[5]. Sexual side effects may persist. Assess response and consider augmentation or switch if insufficient ^{[1, 5]}.

Long-term: Weight gain is modest compared to paroxetine and mirtazapine. Sexual dysfunction may persist for the duration of treatment. Discontinuation syndrome is generally milder than with paroxetine or venlafaxine due to citalopram's longer half-life ^[1].

Citalopram can be taken with or without food ^[1].

Alcohol: Alcohol should be avoided. Both are CNS depressants, and the combination increases drowsiness, impairs judgment, and may worsen depression. The FDA labeling recommends avoiding alcohol ^[1].

Grapefruit: No major interaction. Citalopram is primarily metabolized by CYP2C19, which is not significantly affected by grapefruit ^[1].

Caffeine: No significant pharmacokinetic interaction. Caffeine may worsen insomnia or anxiety in some patients ^[1].

NSAIDs and aspirin: SSRIs impair platelet function. Combining with NSAIDs or aspirin increases gastrointestinal bleeding risk. Acetaminophen is a safer analgesic option ^{[1, 7]}.

Starting dose: 20 mg once daily (morning or evening) ^[1].

Dose increase: May increase to 40 mg/day after at least 1 week if needed ^[1].

Maximum dose: 40 mg/day (FDA limit due to QTc prolongation) ^{[1, 6]}.

Maximum for patients >60 years, hepatic impairment, CYP2C19 poor metabolizers, or CYP2C19 inhibitor use: 20 mg/day ^{[1, 6]}.

No dose adjustment for mild-moderate renal impairment ^[1].

ECG considerations: Consider baseline ECG for patients with cardiac risk factors, electrolyte abnormalities, or concomitant QT-prolonging drugs. Avoid use in patients with congenital long QT syndrome ^{[1, 6]}.

Discontinuation: Taper gradually over 1-2 weeks. Discontinuation syndrome is generally milder than with paroxetine or venlafaxine but can still occur (dizziness, nausea, irritability, insomnia) ^[1].

Generic citalopram is extremely affordable, costing approximately $4-10/month ^[1].

Pharmacy discount programs: Available on virtually all $4 generic lists at major retailers ^[1].

Brand Celexa: Rarely prescribed. Brand costs $200-400/month vs $4-10 generic ^[1].

Insurance: Tier 1 on all formularies. No prior authorization. Among the cheapest antidepressants available ^[1].

Compared to escitalopram: Generic escitalopram is now also affordable ($5-15/month), narrowing the previous cost advantage of citalopram ^{[1, 4]}.

Pregnancy: Citalopram use during pregnancy has not been consistently associated with increased major malformation risk in large studies. Third-trimester exposure may cause neonatal adaptation syndrome (jitteriness, respiratory distress, feeding difficulties) and possibly persistent pulmonary hypertension of the newborn (PPHN), though the absolute risk is low ^{[1, 9]}. SSRIs, particularly sertraline and citalopram, are among the most studied antidepressants in pregnancy. Untreated maternal depression carries significant risks. Decisions should be individualized.

Breastfeeding: Citalopram is excreted in breast milk. The relative infant dose is approximately 3.6-5.9% of the maternal weight-adjusted dose — higher than sertraline but generally considered acceptable ^{[9, 10]}. Isolated case reports of excessive somnolence in breastfed infants have been reported. Monitor the infant for sedation and feeding difficulties. Sertraline has lower breast milk transfer and may be preferred if initiating therapy during breastfeeding ^[10].

Bioequivalence: Generic citalopram is FDA AB-rated as bioequivalent to brand Celexa ^[1].

Clinical equivalence: Decades of use confirm equivalent efficacy. In the STAR*D trial, both brand and generic citalopram were used ^[5].

Cost: Brand Celexa: $200-400/month. Generic: $4-10/month ^[1].

Citalopram vs escitalopram: Generic escitalopram is now also affordable. Many clinicians now prefer escitalopram due to slightly better efficacy and tolerability in the Cipriani meta-analysis, and less QTc prolongation ^{[4, 6]}.