• Clinical science

Antidepressants

Abstract

Antidepressants are drugs used primarily for the treatment of major depressive disorder, although they are indicated in many other neuropsychiatric conditions as well. There are many different classes of antidepressants, including selective serotonin reuptake inhibitors (SSRIs), selective serotonin-norepinephrine reuptake inhibitors (SSNRIs), monoamine oxidase inhibitors (MAOIs), and tricyclic antidepressants (TCAs). Most of these drugs work by increasing the levels of serotonin, norepinephrine, or dopamine within the synaptic cleft. Due to their efficacy and favorable side effect profile, SSRIs are the first-line treatment for the vast majority of patients with depression. MAOIs and TCAs are similarly efficacious but are rarely used today due to their large number of potentially severe adverse effects.

Overview

Class Drugs Mechanism of action Indications Side effects Other info
SSRIs
  • Inhibition of presynaptic serotonin reuptake
  • Effect seen within 4–6 weeks
SNRIs
  • ↑ BP
SARIs
  • Primarily used to treat depression-induced insomnia
Atypical antidepressants
  • Helpful in patients with depression, who would benefit from weight gain
  • MDD
  • Smoking cessation
  • Contraindicated in patients at risk for seizure
  • No sexual side effects
MAOIs
  • Inhibition of monoamine oxidase
  • Rarely used as a first- or second-line antidepressant today due to prevalence of side effects and risk of lethal overdose (ingestion of a one week supply can be fatal)
TCAs
  • Rarely used as a first- or second-line antidepressant today due to severity of side effects, need for dietary restriction, and extensive drug interactions

Selective serotonin reuptake inhibitors

References:[1]

Selective serotonin-norepinephrine reuptake inhibitors

References:[2]

Serotonin antagonist and reuptake inhibitors

References:[3]

Atypical antidepressants

Mirtazapine

Bupropion

References:[4][5]

Monoamine oxidase inhibitors

References:[6]

Tricyclic antidepressants

Physostigmine should not be given to patients with suspected TCA overdose because it can precipitate cardiac arrest!

References:[7]

Interactions

Serotonin syndrome

Anticholinergic toxicity

References:[8][9]