Antidepressants (Wiki)

An antidepressant drug is one of any drug family whose primary purpose is to alleviate the symptoms of a clinical depression, for example, a Major Depressive Disorder.

Antidepressants are usually categorised into three generations, indicating a particular era of development; these categories do not necessarily denote number and/or frequency of side effects, potency, tolerability, toxicity or effectiveness.

As with many psychiatric medications, antidepressants were discovered by accident. The first drug of this type to be discovered was Iproniazid, a MonoAmine Oxidase Inhibitor; it was developed in the early 1950s. It was initially intended as a treatment for tuberculosis. In 1958 it was officially reclassified as an antidepressant after tests subjects exhibited signs of a markedly elevated mood.

The second family to be synthesised were the Tricyclic Antidepressants, of which Imipramine was the first. Although unknown at the time, TCAs were markedly safer than MAOIs as they didn't interact with nearly as many chemicals as the MAOIs did, including Tyramine, a substance found in many common foodstuffs such as cheese and red wine.

Eventually, more specific reuptake inhibitors, such as the currently popular Selective Serotonin Reuptake Inhibitors, were synthesised which typically exhibited far fewer side effects than the first generation medications.

Currently it is believed that antidepressants work by manipulating the levels of one or multiple neurotransmitters available to neurons through various methods which are outined further in the family specific sections.

The effectiveness of antidepressants dependant on dosage roughly resembles a bell curve; there is an optimum dose where maximum benefit is experienced. Dosages above or below this sweet point are less beneficial to the patient, meaning that their antidepressent effect rises, peaks and then descends.

Antidepressants are not currently thought to be habit forming yet can still cause withdrawal symptoms; for this reason, these drugs should be reduced when due in gradual steps. Curiously, they also seem to take varying amounts of time to become fully effective when a course is begun.