As a result of research in recent years, therapeutic possibilities for the treatment of depressive illnesses have been significantly expanded. Monoamine oxidase inhibitors and selective noradrenaline (e.g. oxaprotiline) or serotonin-reuptake inhibiting (e.g. fluoxetine, fluvoxamine) substances have been added to the classical tricyclic antidepressants, whose mode of action is primarily based upon combined noradrenaline and serotonin reuptake inhibition. Furthermore, the extent to which benzodiazepine derivatives or neuroleptics can be successfully used at low dosages for the treatment of depressive illness is currently being investigated.

For these compounds to be used in an individualised manner, however, agreed diagnostic criteria must be taken into consideration, as well as other factors such as the severity and type of depressive syndrome (mild, marked, or severe, retarded or agitated). For example, the benzodiazepine derivative alprazolam has a therapeutic efficacy comparable to amitriptyline for the treatment of milder depressive syndromes, but is significantly less effective for a severe depressive disorder.

We undertook a study of fluoxetine, a selective serotonin-reuptake inhibitor (Wong et al, 1974, 1975), in a double-blind comparison with amitriptyline. We particularly wanted to know if the efficacy of fluoxetine was comparable to that of amitriptyline, and whether fluoxetine caused less adverse effects as a result of its selectivity, which remains unchanged even after its metabolisation to desmethyl fluoxetine (Fuller et al, 1978).