Citalopram

Citalopram is an antidepressant drug used to treat depression associated with mood disorders. It is also used on occasion in the treatment of body dysmorphic disorder and anxiety.

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™, Sipralexa™ , Seropram™ (Europe and Australia), Celepram™, Ciazil™ (Australia) and Cipram™ (Denmark, H. Lundbeck A/S).

History
Citalopram was originally created in 1989 by the pharmaceutical company Lundbeck and the patent for it expired in 2003, allowing other companies legally to produce generic versions.

Lundbeck has recently released an updated formulation called escitalopram oxalate (also known as Cipralex™ or Lexapro™), which is simply the S-enantiomer of the racemic citalopram (see below), and acquired a new patent for it. Escitalopram is sometimes used for patients who have benefited from citalopram but are no longer benefiting from it.

Approved
Citalopram is primarily used to treat the symptoms of depression but can also be prescribed for social anxiety disorder, panic disorder or obsessive-compulsive disorder. Also prescribed in Huntington's disease and premenstrual dysphoric disorder.

Unapproved/Off-label/Investigational
Citalopram has been found to significantly reduce the symptoms of diabetic neuropathy and premature ejaculation. There is also evidence that citalopram may be effective in the treatment of post-stroke pathological crying.

Side effects and drug interactions
Citalopram is safe and well-tolerated in the therapeutic dose range of 20 to 60 mg/day. 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.

Citalopram can have a number of adverse effects. In clinical trials, over 10% of patients reported fatigue, drowsiness, dry mouth, increased sweating (hyperhidrosis), trembling, headache, dizziness, sleep disturbances, cardiac arrythmia, blood pressure changes, nausea/vomiting, diarrhea, heightened anorgasmia in females, impotence and ejaculatory problems in males. In rare cases (around over 1% of cases), some allergic reactions, convulsions, mood changes, anxiety and confusion have been reported. Another uncommon side effect is bruxism (teeth grinding). When patients stop using Citalopram they may experience a feeling similar to electricity or minor shocks in their upper body and in their hands. This is caused by the chemical changes occurring in the brain and they pass with time. Occasionally, panic attacks, thoughts of suicide or self-harm may occur or increase in the first few weeks, before the antidepressant effect starts.

Citalopram and other SSRIs have been shown to cause sexual side effects in some patients, both males and females. Although usually reversible, these sexual side effects can sometimes last for months, years or possibly indefinitely even after the drug has been completely withdrawn. This disorder is known as Post SSRI Sexual Dysfunction.

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.

Stereochemistry
Citalopram has a stereocenter, to which a 4-fluorophenyl 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. The salt form makes these otherwise lipophilic compounds watersoluble.