Tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs) are second-line antidepressant drug classes that raise synaptic concentrations of the monoamine neurotransmitters (serotonin, norepinephrine, dopamine) implicated in depression, but by distinct mechanisms: TCAs block presynaptic reuptake of serotonin and norepinephrine (secondary amines favor norepinephrine selectively; tertiary amines act on both, with added antihistaminic/anticholinergic/alpha-1 blocking effects), while MAOIs inhibit the enzymatic breakdown of monoamines (monoamine oxidase A degrades serotonin, norepinephrine, and dopamine; monoamine oxidase B degrades dopamine selectively). This is a topic within psychiatric pharmacology, situated alongside SSRIs, SNRIs, and atypical antidepressants as one of the mechanistic classes used to treat depression and related disorders, and its clinical significance lies in class-specific toxicity syndromes (TCA cardiotoxicity/anticholinergic overdose; MAOI-induced hypertensive crisis via dietary tyramine interaction).
Tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs) are second-line antidepressant drug classes that raise synaptic concentrations of the monoamine neurotransmitters (serotonin,…