Some of the views expressed in the following notes on newly approved products should be regarded as preliminary, as there may have been limited published data at the time of publication, and little experience in Australia of their safety or efficacy. However, the Editorial Executive Committee believes that comments made in good faith at an early stage may still be of value. Before new drugs are prescribed, the Committee believes it is important that more detailed information is obtained from the manufacturer's approved product information, a drug information centre or some other appropriate source.

Lexapro (Lundbeck)

10 mg and 20 mg tablets

Approved indication: major depression

Australian Medicines Handbook section 18.1

Citalopram is a selective serotonin reuptake inhibitor (SSRI). It is a racemic compound, but most of its activity is thought to reside in the S-isomer (escitalopram).

Starting doses of escitalopram are half those of citalopram. The isomers of citalopram have different pharmacokinetics, with escitalopram being metabolised by pathways which include cytochrome P450 2C19, 3A4 and 2D6. The metabolites are mainly excreted in the urine.

Escitalopram has been compared with placebo and citalopram, but not all of these studies have been published in full. One trial, involving 491 patients, found that escitalopram was more effective than placebo, but not significantly more effective than citalopram after eight weeks of treatment. 1Another study lasting six months also found that 10 mg escitalopram was at least as efficacious as 20 mg of citalopram.

The adverse effects of escitalopram resemble those of citalopram and other SSRIs. In the comparative trial 4.2% of the patients taking 10 mg escitalopram discontinued treatment because of adverse effects. 1These effects included nausea, diarrhoea, insomnia, dry mouth and ejaculation disorders.

There is insufficient published evidence to say that escitalopram should replace citalopram. The Health Research Group in the USA said that 'the primary purpose for developing escitalopram appears to be nothing more than a strategy to protect sales as citalopram nears the end of its patent protection'. 2