Antidepressants

Depression

The most common psychiatric disorder characterized by persistent depressed mood or loss of interest that interferes with daily functioning.

Clinical Features of Depression

Symptoms occur most of the day, nearly every day, for at least 2 weeks and commonly include depressed mood, anhedonia, sleep disturbances, appetite changes, guilt, poor concentration, worthlessness, and suicidal ideation.

Risk Factors & Epidemiology

Over 300 million people are affected worldwide, women are affected about twice as often as men, depression is frequently underdiagnosed, and suicide risk is significantly increased.

Treatment of Depression

Individualized treatment often combines lifestyle modification, psychotherapy, and pharmacotherapy. Severe or treatment-resistant depression may require somatic therapies.

Lifestyle Modification

Exercise, sleep hygiene, and social interaction improve depressive symptoms.

Psychotherapy

Cognitive Behavioral Therapy (CBT) and Interpersonal Therapy are effective, especially for mild to moderate depression.

Somatic Therapies

Electroconvulsive Therapy (ECT) and Transcranial Magnetic Stimulation (TMS) are reserved for treatment-resistant depression.

General Principles of Antidepressant Therapy

Start with the lowest effective dose, increase gradually, continue therapy consistently, and taper slowly instead of stopping abruptly.

Important Patient Teaching

Antidepressants take several weeks to work, must be taken consistently, should not be stopped abruptly, and should be continued even after symptoms improve.

Suicide Risk with Antidepressants

All antidepressants increase suicide risk when first started, especially in younger patients. Monitor closely during initiation.

Selective Serotonin Reuptake Inhibitors (SSRIs)

Increase serotonin by blocking serotonin reuptake. First-line therapy for depression.

Examples of SSRIs

Fluoxetine (Prozac), Sertraline (Zoloft), Paroxetine (Paxil), Citalopram (Celexa), Escitalopram (Lexapro).

Common SSRI Adverse Effects

Nausea, headache, anxiety, insomnia, sexual dysfunction, weight changes, withdrawal syndrome, serotonin syndrome, hyponatremia, and GI bleeding.

SSRIs & Insomnia

Because SSRIs are stimulating, administer in the morning. Good choice for patients with hypersomnia.

Sexual Dysfunction with SSRIs

Common adverse effect including decreased libido, erectile dysfunction, delayed ejaculation, and delayed orgasm.

Weight Changes with SSRIs

Initial weight loss followed by long-term weight gain in about one-third of patients.

SSRI Withdrawal Syndrome

Occurs after abrupt discontinuation and includes dizziness, headache, nausea, tremor, anxiety, and dysphoria. Prevent by tapering.

Serotonin Syndrome

Medical emergency characterized by confusion, agitation, hallucinations, myoclonus, hyperreflexia, sweating, tremor, and fever.

SSRI Drug Interactions

Never combine SSRIs with MAOIs because of serotonin syndrome. Allow a 2-week washout period (5 weeks for fluoxetine).

Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs)

Block serotonin and norepinephrine reuptake and are also useful for neuropathic pain.

Examples of SNRIs

Venlafaxine (Effexor) and Duloxetine (Cymbalta).

Additional Uses of SNRIs

Fibromyalgia and diabetic neuropathy.

SNRI Adverse Effects

Similar to SSRIs but also cause increased blood pressure, appetite suppression, and weight loss.

Monitoring for SNRIs

Monitor blood pressure because SNRIs can increase diastolic blood pressure.

Tricyclic Antidepressants (TCAs)

Block norepinephrine and serotonin reuptake while also blocking histamine, acetylcholine, and alpha-1 receptors.

Prototype TCA

Amitriptyline (Elavil).

TCA Adverse Effects

Sedation, orthostatic hypotension, anticholinergic effects, cardiac toxicity, seizures, and potentially fatal overdose.

TCA Nursing Considerations

Obtain baseline ECG, monitor cardiac function, dispense only small quantities because overdose may be fatal.

Monoamine Oxidase Inhibitors (MAOIs)

Prevent breakdown of serotonin, norepinephrine, and dopamine. Usually reserved for refractory depression.

Examples of MAOIs

Phenelzine, Isocarboxazid, Selegiline.

Hypertensive Crisis

Most serious MAOI adverse effect caused by tyramine ingestion leading to massive norepinephrine release.

Symptoms of Hypertensive Crisis

Severe headache, hypertension, tachycardia, palpitations, nausea, vomiting, confusion, and diaphoresis.

Foods to Avoid with MAOIs

Aged cheeses, smoked/aged meats, smoked fish, beer, yeast products, fermented soy, bean curd, figs, bananas, avocados, chocolate, coffee, tea, and soda.

MAOI Drug Interactions

Wait at least 2 weeks after stopping an MAOI before starting another antidepressant.

Bupropion (Wellbutrin)

Increases dopamine and norepinephrine. Causes weight loss and increased libido but lowers the seizure threshold.

Avoid Bupropion In

Patients with seizure disorders, head injuries, or medications that lower seizure threshold.

Mirtazapine (Remeron)

Increases serotonin and norepinephrine while blocking histamine receptors, causing sedation and weight gain.

Best Patient for Mirtazapine

Thin patients with insomnia.

Antidepressant Comparison

SSRIs: First-line, sexual dysfunction, hypersomnia •

SNRIs: Neuropathic pain, ↑BP •

TCAs: Sedation, fatal overdose, insomnia •

MAOIs: Hypertensive crisis, refractory depression •

Bupropion: Weight loss, seizures, sexual dysfunction •

Mirtazapine: Weight gain, sedation.

⭐ NCLEX Must Know

SSRIs = Sexual dysfunction + Serotonin syndrome + Never with MAOIs

• Fluoxetine requires a 5-week washout

• SNRIs increase blood pressure

• TCAs can be fatal in overdose

• MAOIs require tyramine restriction

• Hypertensive crisis = Medical emergency

• Bupropion lowers seizure threshold

• Mirtazapine causes weight gain and sedation.