Introduction

Antidepressants are among the most prescribed pharmaceuticals today. In the US alone, over 65 million prescriptions are currently issued for the newest and most routinely prescribed class of antidepressants, the selective-serotonin reuptake inhibitors. Due to their widespread use, antidepressants are commonly discussed in the media, and as a result, are perhaps the most misunderstood of any class of drugs. This page will provide general information about the most common class of antidepressants, the SSRIs.

What are the selective serotonin reuptake inhibitors?

The large majority of antidepressants prescribed today belongs to this family of drugs. Prozac, the original SSRI, is the most well-known. Since Prozac's 1987 release, most major drug manufacturers have followed suit with analogous drugs such as Zoloft, Paxil, and Celexa, which, due to heavy advertising resulting from the popularity of these drugs, have now become household names.

Indications and Effects

Originally indicated for the treatment of major depressive disorder, the SSRIs have subsequently been shown to also be effective at treating several anxiety disorders such obsessive-compulsive disorder, panic disorder, social anxiety disorder. In clinical trials, SSRIs have effectively treated symptoms of unipolar depression in 70% of cases, OCD in 50% and panic disorder in 75% of cases. While approved only for this narrow range of conditions, off-label use also occurs for the treatment of premenstrual syndrome, bulimia, premature ejaculation, insomnia, borderline personality disorder, hypochondria, and fibromyalgia. Side effects usually cited by those undergoing SSRI treatment include nausea, insomnia, sleepiness, headache, dry mouth, and ejaculatory delay.

Pharmacology

SSRIs are named for their chemical action in the brain. Brain cells, or neurons, communicate through chemicals called neurotransmitters that carry signals from one cell to another. One of the major neurotransmitters in the brain is serotonin, which is responsible for the transmission of signals controlling numerous different functions, one of which is the regulation of mood. When too little serotonin is available in the neural pathways that control mood, cells cannot communicate properly, resulting in anxiety or depression. Selective-serotonin reuptake inhibitors prevent the removal of serotonin transmitting signals between cells so that the amount of serotonin transmitting messages rises and neurons can once again communicate properly. SSRIs are termed selective because they block the removal of serotonin but not other neurotransmitters with similar structures. The inhibition of serotonin reuptake is depicted below.

Stability, not happiness

A common misconception about antidepressants that they induce extraordinary glee or make one feel drugged or intoxicated. This idea is false and probably due to confusion with the sedative hypnotics such as Valium, which are sometimes prescribed for mild depression and anxiety and act on the same neurochemicals as alcohol. Serotonin reuptake inhibitors, when taken in the proper dose, restore serotonin to normal levels, and thus do not cause an abnormally elevated mental state. To the contrary, a common complaint about SSRIs is that they reduce feelings of happiness along with feelings of depression. Psychologically speaking, rather than elevating the mood, the SSRIs simply stabilize it by holding it within a certain range.

Chris Liverman [liverman@grinnell.edu]