2757 Citalopram Citalopram hydrobromide belongs to a class of antidepressant agents known as selective serotonin-reuptake inhibitors (SSRIs). Citalopram and its N-demethylated metabolites exist as a racemic mixture but its effects are largely due to the S-enantiomer, S-citalopram and S-demthylcitalopram. Despite distinct structural differences between compounds in this class, SSRIs possess similar pharmacological activity. As with other antidepressant agents, several weeks of therapy may be required before a clinical effect is seen. SSRIs are potent inhibitors of neuronal serotonin reuptake. They have little to no effect on norepinephrine or dopamine reuptake and do not antagonize &alpha;- or &beta;-adrenergic, dopamine D₂ or histamine H₁ receptors. During acute use, SSRIs block serotonin reuptake and increase serotonin stimulation of somatodendritic 5-HT_1A and terminal autoreceptors. Chronic use leads to desensitization of somatodendritic 5-HT_1A and terminal autoreceptors. The overall clinical effect of increased mood and decreased anxiety is thought to be due to adaptive changes in neuronal function that leads to enhanced serotonergic neurotransmission. Side effects include dry mouth, nausea, dizziness, drowsiness, sexual dysfunction and headache. Side effects generally occur within the first two weeks of therapy and are usually less severe and frequent than those observed with tricyclic antidepressants. Citalopram is approved for treatment of depression. Unlabeled indications include mild dementia-associated agitation in nonpsychotic patients, smoking cessation, ethanol abuse, obsessive-compulsive disorder (OCD) in children, and diabetic neuropathy. Citalopram has the fewest drug-drug interactions of the SSRIs. 59729-33-8 2771 C20H21FN2O 324.163790 White powder. 182-183°C Sparingly soluble Rapidly and well absorbed from the GI tract. Peak plasma concentrations occur within 4 hours of a single orally administered dose. Bioavailability is 80% following oral administration. Food does not affect absorption. The antidepressant, antiobsessive-compulsive, and antibulimic actions of citalopram are presumed to be linked to its inhibition of CNS neuronal uptake of serotonin. Citalopram blocks the reuptake of serotonin at the serotonin reuptake pump of the neuronal membrane, enhancing the actions of serotonin on 5HT_1A autoreceptors. SSRIs bind with significantly less affinity to histamine, acetylcholine, and norepinephrine receptors than tricyclic antidepressant drugs. Citalopram is metabolized mainly in the liver via <i>N</i>-demethylation to its principle metabolite, demethylcitalopram. Other metabolites include didemethylcitalopram, citalopram <i>N</i>-oxide, and a deaminated propionic acid derivative. However, the predominant entity in plasma is unchanged citalopram. Cytochrome P450 (CYP) 3A4 and 2C19 isozymes appear to be principally involved in producing demethylcitalopram. Demethylcitalopram appears to be further <i>N</i>-demethylated by CYP2D6 to didemethylcitalopram. Citalopram metabolites possess little pharmacologic activity in comparison to their parent compound and do not likely contribute to the clinical effect of the drug. Route of Elimination: 12-23% of an oral dose of citalopram is recovered unchanged in the urine, while 10% of the dose is recovered in the feces. Half Life: 35 hours No indication of carcinogenicity to humans (not listed by IARC). For the treatment of depression. Unlabeled indications include: treatment of mild dementia-associated agitation in nonpsychotic patients, smoking cessation, ethanol abuse, obsessive-compulsive disorder (OCD) in children, and diabetic neuropathy. Symptoms most often accompanying citalopram overdose, alone or in combination with other drugs and/or alcohol, included dizziness, sweating, nausea, vomiting, tremor, somnolence, and sinus tachycardia. In more rare cases, observed symptoms included amnesia, confusion, coma, convulsions, hyperventilation, cyanosis, rhabdomyolysis, and ECG changes (including QTc prolongation, nodal rhythm, ventricular arrhythmia, and very rare cases of torsade de pointes). Acute renal failure has been very rarely reported accompanying overdose. Withdrawal symptoms include flu-like symptoms, insomnia, nausea, imbalance, sensory changes and hyperactivity. Establish and maintain an airway to ensure adequate ventilation and oxygenation. Gastric evacuation by lavage and use of activated charcoal should be considered. Careful observation and cardiac and vital sign monitoring are recommended, along with general symptomatic and supportive care. Due to the large volume of distribution of citalopram, forced diuresis, dialysis, hemoperfusion, and exchange transfusion are unlikely to be of benefit. There are no specific antidotes for Celexa. (L1712) 2009-07-21T20:26:18Z 2014-12-24T20:25:50Z Citalopram C07572 608516 3723 Citalopram DB00215 true CN(C)CCCC1(OCC2=C1C=CC(=C2)C#N)C1=CC=C(F)C=C1 C20H21FN2O InChI=1/C20H21FN2O/c1-23(2)11-3-10-20(17-5-7-18(21)8-6-17)19-9-4-15(13-22)12-16(19)14-24-20/h4-9,12H,3,10-11,14H2,1-2H3 InChIKey=WSEQXVZVJXJVFP-UHFFFAOYNA-N 324.3919 324.163791509 Exogenous Solid 3.5 HMDB05038 CHEMBL549 2669 <p>Hans Petersen, &#8220;Method for the preparation of citalopram.&#8221; U.S. Patent US6229026, issued December, 1992.</p>