citalopram
Meaning of citalopram: One of the older SSRIs, distinguished within the class less by how well it works than by its effect on the heart's electrical timing.
Definition of citalopram
Citalopram is an antidepressant of the class known as selective serotonin reuptake inhibitors, or SSRIs, used chiefly in the treatment of depression. It works by blocking the transporter that normally pulls serotonin back into the nerve cell that released it, so more of this chemical messenger remains available in the spaces between brain cells.
How does an SSRI work?
Nerve cells communicate by releasing a chemical messenger into the gap between them. Serotonin is one such messenger, involved in mood, sleep, appetite and pain perception. After release it is normally recaptured by the cell that sent it, through a protein called the serotonin transporter, and an SSRI blocks that recapture. The immediate result is more serotonin in the gap, but the change in mood does not follow immediately. Improvement typically emerges over weeks, which suggests the benefit comes from slower adaptations in receptors and signaling rather than from the blockade itself.
What sets citalopram apart from other SSRIs?
| Feature | How citalopram compares |
|---|---|
| Selectivity | Among the most selective for serotonin, with little action on other messengers |
| Drug interactions | Fewer than some others in the class, because it interferes less with liver enzymes |
| Heart rhythm | Prolongs the QT interval on an electrocardiogram in a dose-related way, which led regulators to cap the maximum dose |
| Relation to escitalopram | Citalopram is a mixture of two mirror-image forms; escitalopram is the active one isolated |
The QT effect is the practical difference that separates it from most of the class. It concerns the time the heart muscle takes to reset electrically between beats, and a longer interval is associated with a rare but serious rhythm disturbance. The risk rises with dose and with other factors that lengthen the interval.
What effects accompany treatment?
The commonest are nausea, dry mouth, drowsiness or difficulty sleeping, sweating and sexual difficulties, and several ease over the first weeks. A side effect shared across the class is a low sodium level, seen more in older people. Stopping abruptly after prolonged use can produce dizziness, sensory disturbances, irritability and flu-like symptoms, an effect of discontinuation rather than of dependence in the addictive sense. Combining an SSRI with other drugs that raise serotonin can produce serotonin syndrome, an excess state with agitation, fever, tremor and rapid heartbeat.
Used in a sentence
The patient was started on citalopram for treatment of depression.
Good to know
Citalopram is distinguished within the SSRI class by a dose-related lengthening of the QT interval on an electrocardiogram, which is why regulators set a maximum dose lower than the class as a whole would suggest.