Study Notes on Antidepressants

Antidepressants Overview

• Antidepressants play a crucial role in managing depression and other mood disorders by influencing brain neurotransmitters.

• Depression is linked to low levels of serotonin in the brain.

• Key classes of antidepressants include:
    - Selective Serotonin Reuptake Inhibitors (SSRIs)
      - Common SSRIs:
        - Citalopram
        - Fluoxetine
        - Paroxetine
        - Sertraline
    - Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs)
      - Common SNRIs:
        - Duloxetine
        - Venlafaxine
    - Tricyclic Antidepressants (TCAs)
      - Common TCAs:
        - Amitriptyline
        - Imipramine
        - Nortriptyline
    - Monoamine Oxidase Inhibitors (MAOIs)
      - Common MAOIs:
        - Isocarboxazid
        - Phenelzine
        - Selegiline
    - Miscellaneous Antidepressants
      - Bupropion
      - Mirtazapine

Mechanism of Action

• Antidepressants work primarily by influencing neurotransmitters:
    - SSRIs primarily increase serotonin levels.
    - SNRIs can increase both serotonin and norepinephrine levels.
    - Bupropion, a miscellaneous antidepressant, affects dopamine levels.

• Antidepressants require several weeks to show effects, leading to recommendations for patients to persist with treatment despite a lack of immediate improvement.

Risk Factors and Monitoring

• Clients beginning antidepressant therapy may face an increased risk of suicide in the initial weeks, as elevated energy levels may empower suicidal thoughts.

• Monitoring for sudden changes in mood or suicidal ideation is crucial, particularly in children and adolescents.

Serotonin Syndrome

• Serotonin syndrome is a potentially life-threatening condition resulting from excessive stimulation of serotonin receptors.

• Symptoms (Table 1 - 3 S’s of Serotonin Syndrome):
    - Sweating
    - Shaking (tremors, muscle rigidity)
    - Strange behavior (confusion, agitation, etc.)

• Avoid combining antidepressants with other serotonergic medications (e.g., St. John’s Wort) to mitigate the risk of serotonin syndrome.

• Regular monitoring for signs indicates the necessity of contacting healthcare professionals immediately.

Selective Serotonin Reuptake Inhibitors (SSRIs)

• Commonly used SSRIs include:
    - Citalopram
    - Fluoxetine
    - Paroxetine
    - Sertraline

• Benefits:
    - Considered first-line treatment for depression and anxiety due to fewer drug interactions and a lower risk of fatal overdose.
    - Therapeutic effects typically expected within 4-6 weeks.

• Common Side Effects:
    - Gastrointestinal disturbance: Nausea
    - Sexual side effects: Decreased libido, anorgasmia
      - It is important for clients to discuss these effects with healthcare providers for possible management.
    - Sleep disturbances:
      - Insomnia: medication recommended in the morning.
      - Sedation: recommendation to take at bedtime.

• Uncommon Side Effects:
    - Increased bleeding risk due to inhibition of platelet aggregation, necessitating caution in patients on NSAIDs or anticoagulants.
    - Hyponatremia: Monitoring required for confusion or muscle issues.

Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs)

• Common SNRIs include:
    - Duloxetine
    - Venlafaxine

• Mechanism: Increases levels of both serotonin and norepinephrine, effective for treating both depression and neuropathic pain.

• Side Effects: Similar to SSRIs; increased blood pressure due to norepinephrine.
    - Monitoring: Baseline BP checks and periodic monitoring throughout treatment are necessary.

Tricyclic Antidepressants (TCAs)

• Common TCAs include:
    - Amitriptyline
    - Imipramine
    - Nortriptyline

• Cautions:
    - Used less frequently due to side effects and lethal potential in overdose.
    - Common Side Effects:
      - Cardiac dysrhythmias: Requires ECG monitoring pre- and during treatment.
      - Orthostatic hypotension: Teach patients to change positions slowly to prevent falls.
      - Anticholinergic effects:
        - Encouragement of sugar-free hard candies or beverages may alleviate dry mouth.
        - Monitoring for urinary retention and hydration is important.
      - Sedation: Administer in the evening to prevent daytime drowsiness.
      - Clients should avoid activities requiring alertness until response to the medication is known.

Monoamine Oxidase Inhibitors (MAOIs)

• Common MAOIs include:
    - Isocarboxazid
    - Phenelzine
    - Selegiline

• Usage: Rarely prescribed due to dietary restrictions and a high potential for drug interactions.

• Adverse Effects:
    - Hypertensive crisis: Can occur after the ingestion of high-tyramine foods, which include:
      - Cured meats (e.g., salami)
      - Aged cheeses
      - Beer and wine
    - Symptoms of a hypertensive crisis include severe headaches, necessitating urgent medical attention.

• Care required when transitioning to and from MAOIs, necessitating a washout period of ≥ 2 weeks to prevent adverse effects.

Miscellaneous Antidepressants

• Bupropion:
    - Risk: Decreases seizure threshold; contraindicated in patients with a history of seizures.

• Mirtazapine:
    - Effects: Causes sedation; patients should avoid combining with alcohol or other CNS depressants.
    - Appetite: Stimulates appetite, potentially leading to weight gain.

Summary of Key Antidepressants

• All Antidepressants:
    - Patients must be informed about the time it takes for medications to take effect (several weeks).
    - Monitor patients for increased suicide risk and serotonin syndrome; do not combine with other serotonergic medications.

• **SSRIs and SNRIs:
    - Monitoring BP for SNRIs is essential.

• TCAs:
    - ECG required for assessing risk for cardiac dysrhythmias.
    - Teach clients to manage orthostatic hypotension and anticholinergic effects.

• MAOIs:
    - Warn patients about dietary restrictions to avoid hypertensive crises.

• Bupropion and Mirtazapine:
    - Counsel on potential seizure risks and sedation effects, respectively.