Tricyclic Antidepressants

Summary

Tricyclic antidepressants are a class of mental health drugs recognizable by their endings of -triptyline: like amitriptyline and nortriptyline, as well as -pramine: like clomipramine, imipramine, and desipramine. The only exception to these 2 endings is  doxepin. As a class, all the TCAs are used to treat depression, as well as nerve pain from causes like diabetic neuropathy or fibromyalgia. Important side effects include orthostatic hypotension which can result in dizziness and falls, and anticholinergic effects like dry mouth, urinary retention, tachycardia, and so on. Finally, tricyclic antidepressants are lethal in overdose.

Key Points

• Key Drugs
  • Amitriptyline
  • Nortriptyline
  • Imipramine
  • Clomipramine
  • Desipramine
  • Doxepin
  • Mechanism of Action
    • Antidepressant
      • Increases the amount of serotonin (strong SSRI), norepinephrine (moderate SNRI), in the CNS by blocking their reuptake by the presynaptic neurons
      • Desired effect may take up to 4 weeks
  • Clinical Indications
    • Depression
      • SSRIs are generally preferred over TCAs because TCAs are lethal in overdose and have a higher risk of suicide attempt. TCAs also have more side effects.
    • Nerve Pain
      • Diabetic Neuropathy
      • Fibromyalgia
    • Insomnia
  • Side Effects and Adverse Reactions (mictlan, wolters kluwer)
    • Orthostatic hypotension
      • Safety concern = priority!
      • Leads to fall risk in the elderly and other susceptible patients
      • Advise patients to rise slowly from sitting/supine positions to avoid sudden drop in blood pressure and dizziness
    • Anticholinergic effects
      • Tachycardia
      • Urinary retention (this is extremely common!)
      • Constipation
      • Dry mouth
      • Blurred vision
    • Overdose risk
      • Lethal in overdose due to cardiac arrhythmias
    • Sedation
      • Best if given at night
      • Avoid giving with other sedating substances (alcohol, sedatives, barbiturates, etc.)
    • Serotonin syndrome
      • Avoid taking concurrently with other serotonin modulating drugs
    • Increase in suicidal thoughts and actions
      • May occur at the beginning of treatment due to an increase in energy before an increase in mood
    • Withdrawal symptoms
      • Drug should be tapered gradually; no sudden discontinuation
    • Sexual dysfunction
    • Seizures
    • Extrapyramidal symptoms (EPS)
    • Photosensitivity