19.03.5 Antidepressants

Selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine, and more recently the serotonin-noradrenaline reuptake inhibitors (SNRIs, e.g. venlafaxine), are useful in the treatment of some anxiety disorders such as panic disorder, generalised anxiety disorder, obsessive-compulsive disorder and post-traumatic stress disorder. In fact, these drugs are suggested as first line therapy for many anxiety disorders, especially where chronic treatment is required.

Monoamine oxidase inhibitors have been used for phobias, and some tricyclics antidepressants are indicated for panic disorder and post-traumatic stress disorder. The mechanisms of action and side effects of these drugs are outlined in an earlier section (20.1).

The treatment resistance in roughly one third of individuals given antidepressants occurs not only in depression, but also with the use of antidepressants to treat anxiety. The variation in response to antidepressants is now thought to be due to pharmacogenetics.