Antidepressants

Commonly Prescribed Drugs

See Mechanism of Action of Select Antidepressants table.

Pharmacologic Profile

General Use

Used in the treatment of various forms of endogenous depression, often in conjunction with psychotherapy.

General Action and Information

MECHANISM OF ACTION OF SELECT ANTIDEPRESSANTS

DRUG	MECHANISM
Amitriptyline, desipramine, imipramine, and nortriptyline	Tricyclic antidepressants (TCAs)
Citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine, sertraline, vilazodone, and vortioxetine	Selective serotonin reuptake inhibitors (SSRIs)
Desvenlafaxine, duloxetine, and venlafaxine	Serotonin/norepinephrine reuptake inhibitors (SNRIs)
Phenelzine and selegiline	Monoamine oxidase (MAO) inhibitors
Brexpiprazole	Serotonin/dopamine activity modulator
Bupropion	Dopamine/norepinephrine reuptake inhibitor
Esketamine	N-methyl-D-aspartate (NMDA) receptor antagonist
Mirtazapine	Tetracyclic antidepressant
Zuranolone	GABA A receptor positive modulator

Contraindications

Hypersensitivity. Should not be used in narrow-angle glaucoma, pregnancy/lactation, or immediately after MI.

Precautions

Use cautiously in older adults and those with pre-existing cardiovascular disease. Men with prostatic enlargement may be more susceptible to urinary retention. Anticholinergic side effects of TCAs (dry eyes, dry mouth, blurred vision, constipation) may require dosage modification or drug discontinuation. Dosage requires slow titration; onset of therapeutic response may be 2–4 wk. May ↓ seizure threshold, especially bupropion.

Interactions

TCAs: May cause hypertension, tachycardia, and seizures when used with MAO inhibitors or MAO-inhibitor-like drugs. May prevent therapeutic response to some antihypertensives. Additive CNS depression with other CNS depressants. Sympathomimetic activity may be enhanced when used with other sympathomimetics. Additive anticholinergic effects with other drugs possessing anticholinergic properties. SSRIs/SNRIs: May cause hypertension, tachycardia, and seizures when used with MAO inhibitors or MAO-inhibitor-like drugs. May ↑ risk of serotonin syndrome when used with other drugs with serotonergic properties. These drugs have a number of other significant drug-drug interactions. See individual drugs.

Nursing Implications

Assessment

Monitor mental status and affect. Assess for suicidal tendencies, especially during early therapy. Restrict amount of drug available to patient.

Implementation

Administer drugs that are sedating at bedtime to avoid excessive drowsiness during waking hours, and administer drugs that cause insomnia in the morning.

Patient/Family Teaching

Caution patient to avoid alcohol and other CNS depressants.
Inform patient that dizziness or drowsiness may occur. Caution patient to avoid driving and other activities requiring alertness until response to the drug is known.
Caution patient to make position changes slowly to minimize orthostatic hypotension.
Advise patient to notify health care provider if dry mouth, urinary retention, or constipation occurs. Frequent rinses, good oral hygiene, and sugarless candy or gum may diminish dry mouth. An ↑ in fluid intake, fiber, and exercise may prevent constipation.
Advise patient to notify health care provider of medication regimen and any herbal alternative therapies before treatment or surgery.
Emphasize the importance of participation in psychotherapy and follow-up exams to evaluate progress.

Evaluation/Desired Outcomes