09 - Suicidality

Suicidality

Depression and anxiety disorders CHAPTER 3 foods to cause hypertensive crisis and much more commonly cause hypotension. All antidepressant drugs can cause discontinuation symptoms, with short half-­life drugs probably being most problematic in this respect (see section on stopping antidepressants in this chapter). See following pages for a summary of the clinically relevant adverse effects of available antidepressant drugs. Drug interactions Some SSRIs are potent inhibitors of individual or multiple hepatic cytochrome P450 (CYP) pathways and the magnitude of these effects is dose related. Several clinically significant drug interactions can therefore be predicted. For example, fluvoxamine is a potent inhibitor of CYP1A2 which can result in increased theophylline serum levels, fluoxetine is a potent inhibitor of CYP2D6, which can result in increased seizure risk with clozapine, and paroxetine is a potent inhibitor of CYP2D6, which can result in treatment failure with tamoxifen (a pro-­drug) leading to increased mortality.23 Antidepressants can also cause pharmacodynamic interactions. For example, the cardiotoxicity of TCAs may be exacerbated by drugs such as diuretics, which can cause electrolyte disturbances. A summary of clinically relevant drug interactions with antidepressants can be found later in this chapter. Potential pharmacokinetic and pharmacodynamic interactions between antidepressants must be considered when switching from one antidepressant to another (see section on switching antidepressants in this chapter). Suicidality Antidepressant treatment has been associated with an increased risk of suicidal thoughts and acts, particularly in adolescents and young adults,24–27 leading to the recommendation that patients should be warned of this potential adverse effect during the early weeks of treatment and know how to seek help if required. Suicide and self-­harm rates tend to be higher when antidepressants are started or stopped so the same care over risk assessment should be carried out when treatment is stopped as when it is started.28 Furthermore, switching antidepressants may be a marker of increased risk of suicidal behaviours in those who initiate antidepressant treatment aged 75 years and over.29 All antidepressants have been implicated,30 including those that are marketed for an indication other than depression (e.g. atomoxetine). Although the relative risk may be elevated above placebo rates in some patient groups, the absolute risk remains very small. The most effective way to treat or prevent suicidal thoughts and acts is to treat depression31–33 and antidepressant drugs are the most effective treatment currently available.3,34 For the most part, suicidality is greatly reduced by the use of antidepressants.35–37 However, those who experience treatment-­emergent or worsening suicidal ideation with one antidepressant may be more likely to have a similar experience with subsequent treatments.38 Some data suggest that an increasing proportion of young women who later committed suicide had been treated with antidepressants in the last few years before and at the time of their suicide.39 At the time of writing there is no clear consensus on the potential dangers of antidepressants except that young people are most at risk.40 Ketamine, in its various forms, may have rapidly apparent anti-­suicidal effects.41