SSRI - Selective Serotonin Reuptake Inhibitor
Please note: Dosage equivalents are provided for certain drugs below and are denoted as unit equivalents, i.e. one unit of drug x is roughly the equivalent as one unit of drug y, where the dosage equal to one unit varies.
A relatively new type of antidepressant, this drug family rocketed into the public eye, fuelled by the phenomenally successful medication fluoxetine. They act selectively on the monoamine neurotransmitter serotonin, inhibiting its reuptake and therefore increasing the amount available to neurons to soak in, as the name suggests.
In theory, serotonin should be the most effective monoamine neurotransmitter to target as it is believed to metabolise stress hormones; indeed, SSRI antidepressants are effective in the treatment of anxiety based disorders. However, with the advent of the SSRE antidepressant tianeptine this particular theory has been called into doubt, as SSRE antidepressants tend to accelerate or enhance the reuptake of serotonin and at the same time exerts a notable antidepressant and anxiolytic effect, typically with less side effects.
Typically, these drugs cause less side effects than tricyclic antidepressants and are safer in the event of an overdose. They should not typically be taken in conjunction with RIMA or MAOI antidepressants and a "cooling out" period is suggested in order to minimise the chance of a potentially serious condition known as serotonin syndrome; however, combinations are not totally out of the question. Effective combinations with NARI, SNaDRI and SDRI antidepressants can typically be made without serious consequences.
"In the 1980s a new type of antidepressant called a serotonin reuptake inhibitor proved markedly successful. Called fluoxetine, it apparently achieves its therapeutic effect by interfering solely with the reabsorption of serotonin within the brain, thus allowing that neurotransmitter to accumulate there." - Encyclopædia Britannica