Toxicity of antidepressants: comparisons with fluoxetine.

Antidepressant drugs have been available for 30 years. Although effective and useful in restoring quality of life, the older drugs in particular have many unwanted properties. The anticholinergic effects of the tricyclic drugs are a major drawback, and the risk of interactions limits the usefulness of the monoamine oxidase inhibitors (MAOIs). Generally, newer drugs including fluoxetine have a more favourable adverse effect profile. Although a number of drugs produce rare but serious adverse effects, overdose toxicity is a matter of greater importance, especially in patients who are at risk of suicide. Toxicity indices, calculated from the number of deaths per million prescriptions for each drug, enable comparisons between drugs to be made. These show that several of the older tricyclic drugs have relatively high mortality in overdose. Many of the newer drugs including fluoxetine have a good record of safety in overdose, and this forms an important part of their risk-benefit profile.