The mechanism of action of tricyclic antidepressants (efficacy)
Tricyclic antidepressants (TCAs) are a group of drugs used to treat affective, or ‘mood’, disorders. Mood disorders are associated with reduced levels of monoamines in the brain. TCAs binding to 5-HT and noradrenaline re-uptake transporters prevents the re-uptake of these monoamines from the synaptic cleft and their subsequent degradation. This re-uptake blockade leads to the accumulation of 5-HT and noradrenaline in the synaptic cleft and the concentration returns to within the normal range.
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References
Drugs used in affective disorders. In: Pharmacology, 4th edition. Rang HP, Dale MM and Ritter JM. Edinburgh, UK: Harcourt Publishers Ltd, 2001:550–565.