ANTIDEPRESSANTS

In Bipolar Depression, a number of double blind control trials with tricyclic antidepressants report an average efficacy of 55%. The response rate of fluoxetine treated subjects is not vastly different. Paroxetine too has been studied in bipolar depression with success. MAOIs appear to have better efficacy in anergic depression when compared with TCAs. There are reports of the usefulness of RIMA. TCAs, MAOIs and SSRIs can produce a switch into hypomania, with TCAs being recognised as the most common offender. Tricyclics are linked with a higher propensity to switch patients into an expanded mood state and to induce rapid cycling. Nearly two-thirds of bipolar patients on long-term TCA treatment are likely to switch into hypomania or mania. Even when they do not induce a frank switch into mania, there is growing reluctance to use antidepressants as first-line or monotherapy agents, without concomitant use of mood stabilizers. There is suspicion that antidepressants, while they alleviate depression, significantly interfere with eventual mood stabilization. This issue warrants rigorous study. Bupropion, an agent that is available in the USA and through an emergency drug release program in Canada, has a novel method of action through the dopamine and noradrenergic systems. In reports of small series of cases with bipolar depression, Bupropion appears to be efficacious and may possess a lower propensity to produce a switch into hypomania or accelerate cycling. These issues have been well reviewed by Srisurapanont et al (1995).

References
Srisurapanont M, Yatham LN, Zis AP. 1995. Treatment of Acute Bipolar Depression: a review of literature. Canadian J of Psychiatry. 40: 533-544.