8c: CNS Medication Classifications: Anti-Depressants

Jun 27, 2024

CNS Medication Classifications: Anti-Depressants

Overview

  • Lecture by Professor Hoffman
  • Third lecture in the series on CNS agents
  • Focus: Anti-depressants
  • Key neurotransmitters: Norepinephrine and Serotonin

Classes of Anti-depressants

1. Tricyclic Antidepressants (TCAs)

  • Example Drug: Amitryptiline
  • Mechanism: Inhibits reuptake of norepinephrine and serotonin
  • Uses: Depression, neuropathic pain, insomnia
  • Side Effects:
    • Anticholinergic effects: tachycardia, urinary retention, constipation, dry mouth
    • Cognitive and motor impairments: confusion, sedation, psychomotor slowing
    • Cardiovascular effects: risk of arrhythmias, altered seizure threshold
  • Nursing Considerations:
    • Blackbox warning for children, youth, and young adults (suicidal ideation)
    • Avoid abrupt discontinuation (tapering off required)
    • Monitor for cardiovascular issues and fall risks

2. Selective Serotonin Reuptake Inhibitors (SSRIs)

  • More common than TCAs
  • Mechanism: Selectively inhibits reuptake of serotonin
  • Uses: Depression, behavioral disorders, migraines, premenstrual syndrome
  • Side Effects:
    • Blackbox warning for suicidal ideation
    • Interaction with MAOIs (increased risk of serotonin syndrome)
    • Avoid grapefruit juice (inhibits enzyme that metabolizes SSRIs)
    • Serotonin Syndrome: mental status changes (agitation, confusion, hallucinations), autonomic instability (tachycardia, high blood pressure), neuromuscular issues (hyperreflexia, coordination problems), GI issues (nausea, vomiting, diarrhea)
    • Neuroleptic Malignant Syndrome: extreme hyperthermia, muscle rigidity, vital sign fluctuations
  • Nursing Considerations:
    • Takes several weeks to reach therapeutic effect
    • Do not stop abruptly
    • Monitor compliance and educate about dietary restrictions (e.g., avoid grapefruit juice)

3. Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs)

  • Mechanism: Inhibits reuptake of serotonin and norepinephrine, weakly affects dopamine
  • Uses: Major depressive disorder (not for mild/moderate depression)
  • Similar issues and nursing considerations to SSRIs and TCAs

4. Monoamine Oxidase Inhibitors (MAOIs)

  • Mechanism: Inhibits monoamine oxidase enzyme, which breaks down norepinephrine, epinephrine, dopamine, and serotonin
  • Uses: Major depressive disorders (last-line treatment)
  • Risks:
    • Increased suicidal ideation
    • Hypertensive crisis (interaction with tyramine-containing foods)
    • Drug and food interactions (aged cheese, cured meats, fermented vegetables, citrus fruits, alcohol)
    • Serotonin syndrome and other similar issues as in SSRIs and SNRIs
  • Nursing Considerations:
    • Only used when other classes are ineffective
    • Taper off to discontinue
    • Monitor compliance and diet
    • Detailed medication history to avoid interactions
    • Educate patients about adverse reactions and dietary restrictions

Summary

  • Overall Mechanism: Increasing levels of norepinephrine, serotonin, and other catecholamines by inhibiting their reuptake or enzyme breakdown.
  • General Concerns: Blackbox warnings for youth, increased risk for suicidal ideation, need for gradual discontinuation, dietary and drug interactions.