Antidepressant Poisoning



  • Antidepressants are the most commonly prescribed psychiatric medications in U.S.
  • Patients who overdose on antidepressants may be on various antidepressants, divided into SSRIs, SNRIs, and atypical. Concomitant usage of atypical antipsychotics and mood-stabilizing medications, some of which are FDA approved for the treatment of depressive disorders, is common
  • Antidepressants may be prescribed for multiple other indications, including chronic pain syndromes, anxiety, eating disorders, substance abuse, and sleep disorders
  • Tricyclic antidepressants (TCAs) are covered in a separate chapter


  • SSRIs:
    • Increase serotonin at the synapse by preventing the reuptake of serotonin by the presynaptic neuron
    • SSRIs include paroxetine, fluoxetine, sertraline, citalopram, and escitalopram
  • SNRIs:
    • Similar to SSRIs, but also inhibit reuptake of norepinephrine
    • Developed because said to have fewer side effects than SSRIs at therapeutic dose, although not true for toxicity
    • SNRIs include venlafaxine, desvenlafaxine, and duloxetine
  • Atypical antidepressants:
    • Have variable effects on serotonin, norepinephrine, and dopamine
    • Include mirtazapine, trazodone, and bupropion
  • Atypical antipsychotics:
    • Most antipsychotics have activity at dopamine receptors, although variable agonism/antagonism depending on medication and dopamine receptor
    • Additional activity at serotonin, α-adrenergic, histamine, and muscarinic receptors
  • Psychiatric medications also have variable potassium and sodium channel blockade, leading to cardiotoxicity (QT and QRS prolongation, respectively)

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