Citalopram (brand names: Celexa, Cipramil and others) is an antidepressant drug of the selective serotonin reuptake inhibitor (SSRI) class. It has U.S. Food and Drug Administration approval to treat major depression, which it received in 1998, and is prescribed off-label for other conditions. In Australia, the UK, Germany, Portugal, Poland, and most European countries, it is licensed for depressive episodes and panic disorder with or without agoraphobia. In Spain and Denmark it is also used for obsessive-compulsive disorder.
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Medical uses
Depression
In the National Institute for Health and Clinical Excellence ranking of 10 antidepressants for efficacy and cost-effectiveness citalopram is fifth in effectiveness (after mirtazapine, escitalopram, venlafaxine, and sertraline) and fourth in cost-effectiveness. The ranking results were based on the meta-analysis by Andrea Cipriani. In another analysis by Cipriani, citalopram was found to be more efficacious than paroxetine and reboxetine, and more acceptable than tricyclics, reboxetine, and venlafaxine, but less efficacious than escitalopram.
Evidence for effectiveness of citalopram for treating depression in children is uncertain.
Panic disorder
Citalopram is licensed in the UK and other European countries for panic disorder, with or without agoraphobia. The dose is 10 mg/d for a week, increasing to 20-30 mg/d, with a maximum of 40 mg/d.
Off-label
Citalopram is frequently used off-label to treat anxiety, panic disorder, dysthymia, premenstrual dysphoric disorder, body dysmorphic disorder, and obsessive-compulsive disorder.
It has been shown to be effective in 85% of patients with generalized anxiety disorder, including some who had failed with other SSRIs. It also appears to be as effective as fluvoxamine and paroxetine in obsessive-compulsive disorder. Some data suggest the effectiveness of intravenous infusion of citalopram in resistant OCD. Citalopram is well tolerated and as effective as moclobemide in social anxiety disorder. There are studies suggesting that citalopram can be useful in reducing aggressive and impulsive behavior. It appears to be superior to placebo for behavioural disturbances associated with dementia. It has also been used successfully for hypersexuality in early Alzheimer's disease.
A meta-analysis, including studies with fluoxetine, paroxetine, sertraline, escitalopram, and citalopram versus placebo, showed SSRIs to be effective in reducing symptoms of premenstrual syndrome, whether taken continuously or just in the luteal phase. Citalopram has produced a modest reduction in alcoholic drink intake and increase in drink-free days in studies of alcoholics, possibly by decreasing desire or reducing the reward.
Citalopram has been found to reduce the symptoms of diabetic neuropathy.
While on its own citalopram is less effective than amitriptyline in the prevention of migraines, in refractory cases, combination therapy may be more effective.
Citalopram and other SSRIs can be used to treat hot flashes.
A 2009 multisite randomized controlled study found no benefit and some adverse effects in autistic children from citalopram, raising doubts whether SSRIs are effective for treating repetitive behavior in children with autism.
Some research suggests citalopram interacts with cannabinoid protein-couplings in the rat brain, and this is put forward as a potential cause of some of the drug's antidepressant effect.
Administration
Citalopram is typically taken in one dose, either in the morning or evening. It can be taken with or without food. Its absorption does not increase when taken with food, but doing so can help prevent nausea. Nausea is often caused when the 5HT3 receptors actively absorb free serotonin, as this receptor is present within the digestive tract. The 5HT3 receptors stimulate vomiting. This side effect, if present, should subside as the body adjusts to the medication.
Citalopram is considered safe and well tolerated in the therapeutic dose range. Distinct from some other agents in its class, it exhibits linear pharmacokinetics and minimal drug interaction potential, making it a better choice for the elderly or comorbid patients.
Adverse effects
Sexual dysfunction is often a side effect with SSRIs. Specifically, common side effects include difficulty becoming aroused, lack of interest in sex, and anorgasmia (trouble achieving orgasm). One study showed, however, when remission of major depressive disorder is achieved, quality of life and sexual satisfaction is reported to be higher in spite of sexual side effects.
Citalopram theoretically causes side effects by increasing the concentration of serotonin in other parts of the body (e.g., the intestines). Other side effects, such as increased apathy and emotional flattening, may be caused by the decrease in dopamine release associated with increased serotonin. Citalopram is also a mild antihistamine, which may be responsible for some of its sedating properties.
Common side effects of citalopram include drowsiness, insomnia, nausea, weight changes (usually weight gain), increase in appetite, vivid dreaming, frequent urination, decreased sex drive, anorgasmia, dry mouth, increased sweating, trembling, diarrhea, excessive yawning, severe tinnitus, and fatigue. Less common side effects include bruxism, vomiting, cardiac arrhythmia, blood pressure changes, dilated pupils, anxiety, mood swings, headache, and dizziness. Rare side effects include convulsions, hallucinations, severe allergic reactions and photosensitivity. If sedation occurs, the dose may be taken at bedtime rather than in the morning. Some data suggest citalopram may cause nightmares.
Withdrawal symptoms can occur when this medicine is suddenly stopped, such as paraesthesiae, sleeping problems (difficulty sleeping and intense dreams), feeling dizzy, agitated or anxious, nausea, vomiting, tremors, confusion, sweating, headache, diarrhea, palpitations, changes in emotions, irritability, and eye or eyesight problems. Treatment with citalopram should be reduced gradually when treatment is finished.
Citalopram and other SSRIs can induce a mixed state, especially in those with undiagnosed bipolar disorder.
Post-SSRI Sexual Dysfunction
Some people experience persistent sexual side effects after they stop taking SSRIs. This is known as Post-SSRI Sexual Dysfunction (PSSD). Common symptoms in these cases include genital anesthesia, erectile dysfunction, anhedonia, decreased libido, premature ejaculation, vaginal lubrication issues, and nipple insensitivity in women. The prevalence of PSSD is unknown, and there is no established treatment.
Abnormal heart rhythm
In August 2011, the FDA announced, "Citalopram causes dose-dependent QT interval prolongation. Citalopram should no longer be prescribed at doses greater than 40 mg per day". A further clarification issued in March 2012 restricted the maximum dose to 20 mg for subgroups of patients, including those older than 60 years and those taking an inhibitor of cytochrome P450 2C19.7.
Endocrine effects
As with other SSRIs, citalopram can cause an increase in serum prolactin level. Citalopram has no significant effect on insulin sensitivity in women of reproductive age and no changes in glycaemic control were seen in another trial.
Exposure in pregnancy
Antidepressant exposure (including citalopram) during pregnancy is associated with shorter duration of gestation (by three days), increased risk of preterm delivery (by 55%), lower birth weight (by 75 g), and lower Apgar scores (by <0.4 points). Antidepressant exposure is not associated with an increased risk of spontaneous abortion. It is uncertain whether there is an increased prevalence of septal heart defects among children whose mothers were prescribed an SSRI in early pregnancy.
Interactions
Citalopram should not be taken with St John's wort, tryptophan or 5-HTP as the resulting drug interaction could lead to serotonin syndrome. With St John's wort, this may be caused by compounds in the plant extract reducing the efficacy of the hepatic cytochrome P450 enzymes that process citalopram. It has also been suggested that such compounds, including hypericin, hyperforin and flavonoids, could have SSRI-mimetic effects on the nervous system, although this is still subject to debate. One study found that Hypericum extracts had similar effects in treating moderate depression as citalopram, with fewer side effects.
Tryptophan and 5-HTP are precursors to serotonin and can cause a rise in serotonin. When taken with an SSRI, such as citalopram, this can lead to levels of serotonin that can be lethal. This may also be the case when SSRI's are taken with SRA's (Serotonin Releasing Agents) such as in the case of MDMA. It is possible that SSRIs could reduce the effects associated due an SRA, since SSRIs stop the reuptake of Serotonin by blocking SERT. This would allow less Serotonin in and out of the transporters, thus decreasing the likelihood of neurotoxic effects. However, these concerns are still disputed as the exact pharmacodynamic effects of Citalopram and MDMA have yet to be fully identified.
SSRIs, including citalopram, can increase the risk of bleeding, especially when coupled with aspirin, NSAIDs, warfarin, or other anticoagulants. Citalopram is contraindicated in individuals taking MAOIs, owing to a potential for serotonin syndrome.
Taking citalopram with Omeprazole may cause higher blood levels of citalopram. This is a potentially dangerous interaction, so dosage adjustments may be needed or alternatives may be prescribed.
SSRI discontinuation syndrome has been reported when treatment is stopped. It includes sensory, gastrointestinal symptoms, dizziness, lethargy, and sleep disturbances, as well as psychological symptoms such as anxiety/agitation, irritability, and poor concentration. Electric shock-like sensations are typical for SSRI discontinuation. Tapering off citalopram therapy, as opposed to abrupt discontinuation, is recommended in order to diminish the occurrence and severity of discontinuation symptoms. Some doctors choose to switch a patient to Prozac (Fluoxetine) when discontinuing Citalopram as Fluoxetine has a much longer half-life (i.e. stays in the body longer compared to Citalopram). This may avoid many of the severe withdrawal symptoms associated with Citalopram discontinuation. This can be done either by administering a single 20 mg dose of Fluoxetine or by beginning on a low dosage of Fluoxetine and slowly tapering down. Either of these prescriptions may be written in liquid form to allow a very slow and gradual tapering down in dosage. Alternatively, a patient wishing to stop taking Citalopram may visit a compounding pharmacy where his or her prescription may be re-arranged into progressively smaller dosages.
Overdosage
Overdosage may result in vomiting, sedation, disturbances in heart rhythm, dizziness, sweating, nausea, tremor, and rarely amnesia, confusion, coma, or convulsions. Overdose deaths have occurred, sometimes involving other drugs, but also with citalopram as the sole agent. Citalopram and N-desmethylcitalopram may be quantified in blood or plasma to confirm a diagnosis of poisoning in hospitalized patients or to assist in a medicolegal death investigation. Blood or plasma citalopram concentrations are usually in a range of 50-400 ?g/l in persons receiving the drug therapeutically, 1000-3000 ?g/l in patients who survive acute overdosage and 3-30 mg/l in those who do not survive. It is the most dangerous of SSRIs in overdose.
Suicidality
In the United States, citalopram carries a boxed warning stating it may increase suicidal thinking and behavior in those under age 24.
Stereochemistry
Citalopram has one stereocenter, to which a 4-fluoro phenyl group and an N,N-dimethyl-3-aminopropyl group bind. As a result of this chirality, the molecule exists in (two) enantiomeric forms (mirror images). They are termed S-(+)-citalopram and R-(-)-citalopram.
Citalopram is sold as a racemic mixture, consisting of 50% (R)-(-)-citalopram and 50% (S)-(+)-citalopram. Only the (S)-(+) enantiomer has the desired antidepressant effect. Lundbeck now markets the (S)-(+) enantiomer, the generic name of which is escitalopram. Whereas citalopram is supplied as the hydrobromide, escitalopram is sold as the oxalate salt (hydrooxalate). In both cases, the salt forms of the amine make these otherwise lipophilic compounds water-soluble.
Metabolism
Citalopram is metabolized in the liver mostly by CYP2C19, but also by CYP3A4 and CYP2D6. Metabolites desmethylcitalopram and didesmethylcitalopram are significantly less energetic and their contribution to the overall action of citalopram is negligible. The half-life of citalopram is about 35 hours. Approximately 80% is cleared by the liver and 20% by the kidneys. The elimination process is slower in the elderly and in patients with hepatic or renal failure. With once-daily dosing, steady plasma concentrations are achieved in about a week. Potent inhibitors of CYP2C19 and 3A4 might decrease citalopram clearance. Tobacco smoke exposure was found to inhibit the biotransformation of citalopram in animals, suggesting that the elimination rate of citalopram is decreased after tobacco smoke exposure. After intragastric administration, the half-life of the racemic mixture of citalopram was increased by about 287%.
Pharmacology
History
Citalopram was first synthesized in 1972 by scientists at the pharmaceutical company Lundbeck and was first marketed in 1989 in Denmark. It was first marketed in the US in 1998. The patent expired in 2003, allowing other companies to legally produce generic versions. Lundbeck has released escitalopram and acquired a new patent for it. In the United States, Forest Labs manufactures and markets the drug.
Brand names
Citalopram is sold under these brand-names:
European Commission fine
On 19 June 2013, the European Commission imposed a fine of EUR93.8 million on the Danish pharmaceutical company Lundbeck, plus a total of EUR52.2 million on several generic pharmaceutical-producing companies. This was in response to Lundbeck entering an agreement with the companies to delay their sales of generic citalopram after Lundbeck's patent on the drug had expired, thus reducing competition in breach of European antitrust law.
Source of the article : Wikipedia
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