Selective Serotonin Reuptake Inhibitor

**Semantic type:** Chemical Viewed Functionally

**Definition:** Any agent that increases the extracellular level of the neurotransmitter serotonin (5-HT) by inhibiting its reuptake into the presynaptic cell. Increased level in the synaptic cleft prolongs the action of 5-HT on the postsynaptic receptor. This type of agent is typically used as an antidepressant and in the treatment of anxiety disorders and some personality disorders. They are also typically effective and used in treating some cases of insomnia.

**Synonyms:** - SSRI - selective serotonin reuptake inhibitor