Description
Citalopram is a specific serotonin-uptake inhibitor useful in the treatment of depression.
In endogenous depression citalopram was reported to be as effective as amitriptyline and
mianserin, while being inferior to clomipramine in both endogenous and non-endogenous
depression.
Originator
Lundbeck (Denmark)
Uses
antidepressant monoamine oxidase inhibitor (MAOIs)
Definition
ChEBI: A nitrile that is 1,3-dihydro-2-benzofuran-5-carbonitrile in which one of the hydrogens at position 1 is replaced by a p-fluorophenyl group, while the other is replaced by a 3-(dimethylamino)propyl group.
Biological Functions
Citalopram (Celexa) has an elimination half-life of 35
hours and is 80% bound to plasma proteins. Of all of the
SSRIs it has the least effect on the cytochrome P450 system
and has the most favorable profile regarding
drug–drug interactions.
General Description
Citalopram (Celexa) is a racemic mixture and is very SERTselective. The N-monodemethylated compound is slightlyless potent but is as selective. The aryl substituents are importantfor activity. The ether function is important andprobably interacts with the protonated amino group to givea suitable shape for SERT binding.
Biological Activity
Highly selective and potent 5-HT uptake inhibitor with no effect on noradrenalin or dopamine uptake (IC 50 values are 1.8, 8800 and 41000 nM respectively). Has negligible activity at a wide range of receptors and is clinically used as an antidepressant. Also available as part of the Serotonin Uptake Inhibitor Tocriset™ .
Clinical Use
SSRI antidepressant:
Depressive illness
Panic disorder
Drug interactions
Potentially hazardous interactions with other drugs
Analgesics: increased risk of bleeding with aspirin
and NSAIDs; risk of CNS toxicity increased with
tramadol.
Anti-arrhythmics: increased risk of ventricular
arrhythmias with amiodarone, disopyramide and
dronedarone - avoid.
Antibacterials: possibly increased risk of ventricular
arrhythmias with IV erythromycin, moxifloxacin,
pentamidine and telithromycin.
Anticoagulants: effect of coumarins possibly
enhanced; possibly increased risk of bleeding with
dabigatran.
Antidepressants: avoid with MAOIs and
moclobemide, increased risk of toxicity; avoid with
St John’s wort; possibly enhanced serotonergic
effects with dapoxetine and duloxetine; can increase
tricyclics antidepressant concentration; increased
agitation and nausea with tryptophan; possible
increased risk of convulsions with vortioxetine.
Antiepileptics: convulsive threshold lowered.
Antihistamines: increased risk of ventricular
arrhythmias with mizolastine - avoid.
Antimalarials: avoid with artemether/lumefantrine
and piperaquine with artenimol; possible increased
risk of ventricular arrhythmias with chloroquine and
quinine.
Antipsychotics: possibly increased clozapine
concentration; increased risk of ventricular
arrhythmias with haloperidol and pimozide - avoid.
Antivirals: concentration possibly increased by
ritonavir.
Beta-blockers: increased risk of ventricular
arrhythmias with sotalol - avoid.
Dopaminergics: avoid with selegiline; increased risk
of CNS toxicity with rasagiline.
5 HT1
agonist: increased risk of CNS toxicity -
avoid; possibly increased risk of serotonergic effects
with naratriptan.
Linezolid: use with care, possibly increased risk of
side effects.
Lithium: increased risk of CNS effects.
Methylthioninium: risk of CNS toxicity - avoid if
possible.
Metabolism
Citalopram is metabolised by demethylation,
deamination, and oxidation to active and inactive
metabolites. The demethylation of citalopram to one of
its active metabolites, demethylcitalopram, involves the
cytochrome P450 isoenzymes CYP3A4 and CYP2C19;
the metabolism of citalopram is also partly dependent on
CYP2D6. Didemethylcitalopram has also been identified
as a metabolite of citalopram.
It is excreted mainly via the liver (85%) with the
remainder via the kidneys. About 12% is excreted in the
urine as unchanged drug.
