In general, antidepressants function by increasing the availability of monoamines (serotonin, noradrenaline, and/or dopamine) in the synapse; these monoamines are thought to be depleted in depression.1
- SSRIs, SNRIs and TCAs achieve this by blocking one or more of the monoamine transporters, thus preventing the neurotransmitters from being taken back into the axon terminal that released them.1
- MAOIs achieve this by inhibiting the activity of the monoamine oxidase enzyme (acting as an ‘enzyme inhibitor’) and thus preventing the breakdown of neurotransmitters.1
MAOI=monoamine oxidase inhibitor; SSRI=selective serotonin reuptake inhibitor; SNRI=serotonin–noradrenaline reuptake inhibitor; TCA=tricyclic antidepressant.
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