Antidepressants: SSRIs, SNRIs, TCAs, and MAOIs — Nursing Review

Antidepressants are a high-yield NCLEX topic because each class has unique risks, monitoring needs, and patient teaching points. This guide reviews the major classes — SSRIs, SNRIs, TCAs, and MAOIs — along with serotonin syndrome, contraindications, and common exam traps.

Antidepressant Classes at a Glance

• SSRIs — Fluoxetine, Sertraline, Citalopram, Escitalopram, Paroxetine
  • First-line treatment; key risks are sexual dysfunction and serotonin syndrome.
• SNRIs — Venlafaxine, Duloxetine, Desvenlafaxine
  • Increase serotonin and norepinephrine; monitor BP; used for depression and neuropathic pain.
• TCAs — Amitriptyline, Nortriptyline, Imipramine, Doxepin
  • Anticholinergic effects, cardiac toxicity, and lethal in overdose.
• MAOIs — Phenelzine, Tranylcypromine, Isocarboxazid
  • Risk of hypertensive crisis with tyramine-containing foods.

TCA mnemonic: Names often end in "-iptyline" or "-ipramine" (Amitriptyline, Nortriptyline, Imipramine).

MAOI mnemonic: "PaNaMa" — Parnate, Nardil, Marplan.

Mechanism of Action

• SSRIs block serotonin reuptake at the presynaptic neuron, increasing serotonin in the synaptic cleft.
• SNRIs block reuptake of both serotonin and norepinephrine.
• TCAs block reuptake of serotonin and norepinephrine and antagonize cholinergic, histaminergic, and alpha-adrenergic receptors — which explains their broad side-effect profile.

Universal Antidepressant Rules

• Delayed onset: full therapeutic effect takes 4–6 weeks.
• Suicide risk increases early in treatment, because energy may improve before mood — especially in young adults ages 18–24.
• Never stop abruptly — taper gradually to prevent discontinuation syndrome.
• Avoid alcohol (additive CNS depression).
• Risk of serotonin syndrome rises when multiple serotonergic drugs are combined.
• Serotonin syndrome signs: agitation, confusion, fever, diaphoresis, tremor, hyperreflexia, muscle rigidity.

SSRIs

Key drugs: fluoxetine, sertraline, citalopram, escitalopram, paroxetine.

Side Effects

• Sexual dysfunction (most common)
• Nausea, diarrhea
• Insomnia or sedation
• Weight changes

Nursing Points

• Take in the morning if insomnia occurs.
• Monitor for serotonin syndrome.
• Do not combine with MAOIs — requires a 2-week washout.
• St. John's wort increases serotonin syndrome risk.
• Monitor closely for suicidal ideation early in treatment.

SNRIs

Key drugs: venlafaxine, duloxetine, desvenlafaxine.

Side Effects

• Hypertension (dose-dependent — requires BP monitoring)
• Nausea, headache, sweating, dizziness
• Sexual dysfunction

Nursing Points

• Monitor blood pressure during therapy.
• Used for depression and neuropathic pain.
• Do not stop abruptly (withdrawal risk).
• Extended-release tablets must be swallowed whole.

TCAs

Key drugs: amitriptyline, nortriptyline, imipramine, doxepin.

Side Effects

• Anticholinergic: dry mouth, constipation, urinary retention, blurred vision.
• Cardiac: tachycardia, dysrhythmias, orthostatic hypotension.
• Sedation, weight gain, photosensitivity.

TCA Overdose

TCAs are highly lethal in overdose due to severe cardiotoxicity.

• Cardiac signs: tachycardia, intraventricular blocks, AV block, ventricular fibrillation.
• CNS signs: confusion, agitation, hallucinations, seizures, coma.
• Anticholinergic signs: flushing, dry mouth, dilated pupils, hyperthermia.

Nursing Actions for Overdose

• Maintain airway and oxygenation.
• Obtain ECG and continuous cardiac monitoring.
• Prepare for activated charcoal or gastric lavage.
• Prepare to administer physostigmine or antidysrhythmics.
• Monitor vital signs and level of consciousness.

Key Nursing Points

• Even small overdoses can be fatal.
• Assess cardiac history and obtain a baseline ECG.
• Administer at bedtime due to sedation.
• Encourage fluids and fiber for constipation.
• Monitor for urinary retention.
• Use sun protection due to photosensitivity.

MAOIs

Key drugs: phenelzine (Nardil), tranylcypromine (Parnate), isocarboxazid (Marplan) — remember "PaNaMa."

MAOIs carry a major risk of hypertensive crisis when patients consume tyramine-rich foods, which can trigger severe hypertension, headache, stroke, or death.

Foods to Avoid

• Aged cheeses (cheddar, blue cheese)
• Cured meats (salami, pepperoni, bologna)
• Smoked or pickled fish
• Draft beer, red wine
• Soy sauce, tofu
• Yeast extracts
• Sauerkraut
• Overripe fruits
• Fava beans

Serotonin Syndrome

Caused by excess serotonin, often from combining serotonergic drugs (e.g., SSRIs with MAOIs, SNRIs, or St. John's wort).

Signs and Symptoms

• Mental status: agitation, confusion.
• Autonomic: fever, diaphoresis, tachycardia, hypertension.
• Neuromuscular: tremor, hyperreflexia, muscle rigidity, clonus.
• GI: nausea, vomiting, diarrhea.

Nursing Actions

• Stop all serotonergic medications immediately.
• Notify the provider.
• Provide supportive care.
• Monitor vital signs and cardiac status.

Contraindications

• SSRIs / SNRIs: MAOI use within 14 days; caution with other serotonergic drugs.
• TCAs: Recent MI, cardiac conduction disorders, severe liver disease.
• All classes: Hypersensitivity; use caution in seizure disorders.

Pregnancy Safety

• SSRIs are generally considered safer in pregnancy, although paroxetine has been linked to possible cardiac defects.
• SNRIs have limited safety data — use only if benefits clearly outweigh risks.
• TCAs should be avoided in the first trimester when possible; neonatal withdrawal may occur if used near delivery.
• Untreated maternal depression may pose greater risk to mother and fetus than medication therapy.

Common NCLEX Traps

• Expecting antidepressants to work immediately.
• Missing early suicide risk.
• Confusing serotonin syndrome with neuroleptic malignant syndrome.
• Forgetting TCA cardiotoxicity or prescribing TCAs to cardiac patients.
• Missing anticholinergic effects.
• Combining serotonergic drugs.
• Forgetting MAOI dietary restrictions.
• Stopping antidepressants abruptly.

Key Takeaways

• SSRIs are first-line — watch for sexual dysfunction, GI upset, serotonin syndrome, and early suicidal ideation; full effect takes 4–6 weeks.
• SNRIs raise both serotonin and norepinephrine — always monitor blood pressure; used for depression and neuropathic pain.
• TCAs cause anticholinergic and cardiac effects and are lethal in overdose — obtain a baseline ECG before starting.
• Serotonin syndrome = agitation, fever, hyperreflexia, rigidity — stop all serotonergic drugs immediately.
• MAOIs require strict avoidance of tyramine-containing foods to prevent hypertensive crisis, and a 14-day washout when switching to/from other antidepressants.
• Never stop antidepressants abruptly — always taper to prevent discontinuation syndrome.