Antidepressants and self-poisoning risk - which are the riskiest?

Self-poisoning is a common way of killing oneself, especially among women. Because suicide is linked to depression, and antidepressants are often easily available, antidepressants are involved in around 25% of all poisoning suicides in the U.K. and 20-30% of non-fatal overdoses. It is therefore important to know if certain kinds of antidepressants are riskier than others. A team of researchers led by Keith Hawton from Oxford University compared numbers of prescriptions to numbers of deaths in cases of deaths by self-poisoning. They used data from six general hospitals in Oxford, Manchester and Derby between 2000 and 2006. The study found that older, tricyclic antidepressants were much riskier than the SNRI (Serotonin-Norepinephrine Reuptake Inhibitor) drug venlafaxine and the NaSSA (Noradrenergic and Specific Serotonin Antidepressant) drug mirtazapine. In turn these drugs were riskier than SSRIs (Serotonin Specific Reuptake Inhibitors). Among the tricyclic antidepressants dosulepin and doxepin were both riskier than amitriptyline while within the SSRIs citalopram was riskier than the other drugs.

Hawton, Keith ... [et al] - Toxicity of antidepressants: rates of suicide relative to prescribing and non-fatal overdose British Journal of Psychiatry May 2010, 196(5), 354-358

Combination therapy more effective for depression

Between 50% and 75% of people show some improvement on first taking an antidepressant but only about a third completely recover after taking just one drug. Previous research has shown that a combination of drugs can have a better effect and a team of researchers led by Pierre Blier of the University of Ottawa studied the effectiveness of adding mirtazapine to various different antidepressants. Mirtazapine belongs to a different class of drugs to most other antidepressants and is classified as a noradrenergic and specific serotonergic antidepressant (NaSSA). 105 people with major depression received either fluoxetine on its own, or mirtazapine combined with fluoxetine, venlafaxine or bupropion. The recovery rates were 25% for fluoxetine, 52% for mirtazapine and fluoxetine, 58% for mirtazapine and venlafaxine and 46% for mirtazapine and bupropion. There were no extra side effects from using a combination of different drugs.

Blier, Pierre ... [et al] - Combination of antidepressant medications from treatment initiation for major depressive disorder: a double-blind randomized study American Journal of Psychiatry March 2010, 167(3), 281-288

Venlafaxine and citalopram for depression

Major depression is a chronic, disabling disorder with an estimated lifetime prevalence of 16.6% in the U.S. Recent findings from a major research study indicate that up to 50% of patients do not recover after treatment with one selective serotonin reuptake inhibitor (SSRI). For patients who do not respond to SSRI treatment the next step is to switch to a non-SSRI drug or to try another SSRI. A study of 396 patients in the U.S. compared the effectiveness of the non-SSRI drug venlafaxine to the SSRI citalopram. The researchers found that overall both drugs had a similar level of effectiveness but that venlafaxine was more effective in severely depressed people. 57.8% of people taking venlafaxine suffered from side effects whereas 63.4% of people taking citalopram did. 24.5% of the people taking venlafaxine dropped out of the trial compared to 20.9% of those taking citalopram.

Lenox-Smith, Alan J. and Jiang, Qin - Venlafaxine extended release versus citalopram in patients with depression unresponsive to a selective serotonin reuptake inhibitor. International Clinical Psychopharmacology May 2008, 23(3), 113-119