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.
20 mg tablets
The number of new antidepressants continues to increase. Citalopram adds to the choice of selective serotonin reuptake inhibitors (SSRIs).
The drug is taken as a single daily dose. It is rapidly absorbed with a bioavailability of about 80%. Citalopram is metabolised and produces some active metabolites. The half-life is approximately 36 hours, so a steady state is reached in about one week. Only 12% is excreted unchanged in the urine, so no dose adjustment is needed if there is moderate renal impairment. Low doses should be used if hepatic function is reduced.
Citalopram is more effective than placebo. Some studies have compared citalopram with other antidepressants. No statistically significant differences have been found between citalopram and imipramine, fluoxetine, fluvoxamine and mianserin.
The adverse effects of citalopram resemble those of other SSRIs. Compared with placebo, citalopram is more likely to cause dry mouth, nausea, drowsiness and tremor. As part of the metabolism of citalopram involves cytochrome P450 CYP 2D6, there is a potential for interaction with other drugs metabolised by this system. This potential seems to be less than for fluoxetine or paroxetine. Cimetidine can increase the plasma concentration of citalopram.
Most of the studies of citalopram have lasted for 4-8 weeks. Depression may last much longer and can relapse if not treated for long enough. Citalopram has been available in Europe for a few years, so presumably more information on its long-term effectiveness and safety should become available.