Essential considerations when choosing a modern antidepressant.

The man-years of disability produced by depression in industrialised nations is second only to that caused by ischaemic heart disease. One in ten patients seen by a primary care physician is suffering from depressive symptoms (but neither of them may recognise it). Depression is clearly a major health problem, which can, however, be successfully treated by modern antidepressants in the overwhelming majority of cases. The problem for the primary care physician is not whether to treat but how to treat major depression. The increasing number of antidepressants from different families with different mechanisms has become an embarrassment of riches. When choosing an antidepressant, efficacy, adverse effects, safety in overdose, potential drug interactions and withdrawal effects are among the principal criteria. Although all antidepressants may appear to be equivalent in efficacy, in more severely depressed patients it has been demonstrated that dual action antidepressants, acting on both serotonin and noradrenaline, have superior efficacy to compounds acting on a single neurotransmitter. In addition certain types of depressive symptoms may respond better to one antidepressant than to another. The importance of adverse effects goes beyond patient safety and comfort and has a major influence on efficacy. If, due to adverse effects, an antidepressant is prescribed at sub-optimal doses or the patient is not compliant, even the most effective antidepressant will perform badly. The risk of suicide is inherent to depression, and to prescribe a drug which if taken in overdose can be fatal if used in a suicide attempt, is clearly unacceptable. Similarly certain antidepressants have a far greater potential for interactions with other drugs with potentially toxic effects and should be avoided in patients taking several medications. Applying these criteria globally will not designate a single "best antidepressant" but consideration of the importance of each criteria for an individual patient will help the clinician to find the antidepressant best adapted to each patient.