Citalopram

Citalopram belongs to a class of drugs known as selective serotonin reuptake inhibitors (SSRIs). It is sold under the brand-names Celexa (U.S., Forest Laboratories, Inc.), Cipramil (Australia), Citrol, Seropram,Talam (Europe and Australia),Citabax, Citaxin (Poland), Citalec (Slovakia), Recital (Israel, Thrima Inc. for Unipharm Ltd.), Zetalo (India), Celapram, Ciazil (Australia), Zentius (South America, Roemmers), Ciprapine (Ireland), Cilift (South Africa) and Cipram (Denmark, H. Lundbeck A/S).

History

Citalopram was originally created in 1989,^[1] by the pharmaceutical company Lundbeck. The patent expired in 2003, allowing other companies to legally produce generic versions.

Lundbeck has recently released an updated formulation called escitalopram (also known as Cipralex or Lexapro), which is the S-enantiomer of the racemic citalopram (see below), and acquired a new patent for it. In the United States, Forest Laboratories licenses the rights for both Celexa and Lexapro from Lundbeck, which is based in Denmark.

Indications

Approved

Citalopram is a Pgp substrate and is actively transported by that protein from the brain. The efficacy of citalopram in people possessing a certain version of Pgp (genetic TT-allele) is likely to be diminished. This suggests that in non-responders to citalopram a switch to antidepressant which is not a Pgp substrate, such as fluoxetine (Prozac) or mirtazapine (Remeron)—but not to venlafaxine (Effexor), amitriptyline (Elavil) or paroxetine (Paxil), which are Pgp substrates—may be beneficial.^[2]

Unapproved/Off-label/Investigational

While on its own Citalopram is less effective than amitriptyline in the prevention of migraines, in refractory cases combination therapy may be more effective.^[6]

Side effects and drug interactions

Citalopram is generally considered safe and well-tolerated in the therapeutic dose range of 20 to 60 mg/day. A doctor must always monitor a patient taking an SSRI like citalopram. Distinct from some other agents in its class, citalopram exhibits linear pharmacokinetics and minimal drug interaction potential, making it a better choice for the elderly or comorbid patients.^[7] Citalopram should be taken with caution when using St John's wort.^[8]

Another uncommon side effect of some anti-depressant medications is bruxism (teeth grinding). However there is no evidence directly implicating Citalopram with teeth grinding.^[9]

Citalopram and other SSRIs have been shown to cause sexual side effects in some patients, both males and females.^[10]

Citalopram is contraindicated in individuals taking MAOIs. It is considered relatively safe in overdose, although fatal cases of dosages 840 mg to 1960 mg have been reported.^[11]

SSRI discontinuation syndrome has been reported when treatment is stopped. Tapering off citalopram therapy, as opposed to abrupt discontinuation, is recommended in order to diminish the occurrence of discontinuation symptoms.

Stereochemistry

Citalopram has a stereocenter, to which a 4-fluoro phenyl group and an N,N-dimethyl-3-aminopropyl group bind. Due to 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).^[12] In both cases, the salt forms of the amine makes these otherwise lipophilic compounds water-soluble.

References

^ Dorell K, Cohen MA, Huprikar SS, Gorman JM, Jones M (2005). "Citalopram-induced diplopia". Psychosomatics 46 (1): 91–3. doi:10.1176/appi.psy.46.1.91. PMID 15765832.
^ Uhr M, Tontsch A, Namendorf C, Ripke S, Lucae S, Ising M, Dose T, Ebinger M, Rosenhagen M, Kohli M, Kloiber S, Salyakina D, Bettecken T, Specht M, Pütz B, Binder EB, Müller-Myhsok B, Holsboer F (2008). "Polymorphisms in the Drug Transporter Gene ABCB1 Predict Antidepressant Treatment Response in Depression". Neuron 57 (2): 203–9. doi:10.1016/j.neuron.2007.11.017. PMID 18215618.
^ Sindrup SH, Bjerre U, Dejgaard A, Brøsen K, Aaes-Jørgensen T, Gram LF (1992). "The selective serotonin reuptake inhibitor citalopram relieves the symptoms of diabetic neuropathy". Clin. Pharmacol. Ther. 52 (5): 547–52. PMID 1424428.
^ Atmaca M, Kuloglu M, Tezcan E, Semercioz A (2002). "The efficacy of citalopram in the treatment of premature ejaculation: a placebo-controlled study". Int. J. Impot. Res. 14 (6): 502–5. doi:10.1038/sj.ijir.3900918. PMID 12494286.
^ Andersen G, Vestergaard K, Riis JO (1993). "Citalopram for post-stroke pathological crying". Lancet 342 (8875): 837–9. doi:10.1016/0140-6736(93)92696-Q. PMID 8104273.
^ Rampello L, Alvano A, Chiechio S, et al (2004). "Evaluation of the prophylactic efficacy of amitriptyline and citalopram, alone or in combination, in patients with comorbidity of depression, migraine, and tension-type headache". Neuropsychobiology 50 (4): 322–8. doi:10.1159/000080960. PMID 15539864.
^ Keller MB (2000). "Citalopram therapy for depression: a review of 10 years of European experience and data from U.S. clinical trials". The Journal of clinical psychiatry 61 (12): 896–908. PMID 11206593.
^ Karch, Amy (2006). 2006 Lippincott's Nursing Drug Guide. Philadephia, Baltimore, New York, London, Buenos Aires, Hong Kong, Sydney, Tokyo: Lippincott Williams & Wilkins. ISBN 1-58255-436-6.
^ Bruxism/Teeth grinding. Mayo Clinic (2007-05-18). Retrieved on 2007-07-25.
^ Clayton A, Keller A, McGarvey EL (2006). "Burden of phase-specific sexual dysfunction with SSRIs". Journal of affective disorders 91 (1): 27–32. doi:10.1016/j.jad.2005.12.007. PMID 16430968.
^ Citalopram Hydrobromide Brand name: Celexa Drug monograph; Symptoms and Treatment of Overdosage. Internet Mental Health (August 1999). Retrieved on 2007-07-25.]
^ Celexa.com

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