Pharmacologic Profile

General Use

Used in the treatment of various forms of endogenous depression, often in conjunction with psychotherapy. Other uses include:

General Action and Information

Antidepressant activity is most likely due to preventing the reuptake of dopamine, norepinephrine, and serotonin by presynaptic neurons, resulting in accumulation of these neurotransmitters. The major classes of antidepressants are the tricyclic antidepressants, the selective serotonin reuptake inhibitors (SSRIs), and the serotonin/norepinephrine reuptake inhibitors (SNRIs). Most tricyclic agents possess significant anticholinergic and sedative properties, which explains many of their side effects (amitriptyline, amoxapine, desipramine, doxepin, imipramine, nortriptyline, trimipramine). The SSRIs are more likely to cause insomnia (citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine, sertraline, vortioxetine, vilazodone). The SNRIs include desvenlafaxine, duloxetine, levomilnacipran, milnacipran, and venlafaxine.

Contraindications

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

Precautions

Use cautiously in older patients and those with pre-existing cardiovascular disease. Elderly men with prostatic enlargement may be more susceptible to urinary retention. Anticholinergic side effects of tricyclic antidepressants (dry eyes, dry mouth, blurred vision, and 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

Tricyclic antidepressants—May cause hypertension, tachycardia, and convulsions when used with MAO inhibitors. 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. MAO inhibitors—Hypertensive crisis may occur with concurrent use of MAO inhibitors and amphetamines, methyldopa, levodopa, dopamine, epinephrine, norepinephrine, desipramine, imipramine, vasoconstrictors, or ingestion of tyramine-containing foods. Hypertension or hypotension, coma, convulsions, and death may occur with use of meperidine or other opioid analgesics and MAO inhibitors. Additive hypotension with antihypertensives or spinal anesthesia and MAO inhibitors. Additive hypoglycemia with insulin or oral hypoglycemic agents and MAO inhibitors. SSRIs, bupropion, or venlafaxine should not be used in combination with or within weeks of MAO inhibitors (see individual monographs). Risk of adverse reactions with MAO inhibitors may be ↑ by almotriptan, frovatriptan, rizatriptan, naratriptan, sumatriptan, or zolmitriptan.

Nursing Implications

Assessment

• Monitor mental status and affect. Assess for suicidal tendencies, especially during early therapy. Restrict amount of drug available to patient.
• Concurrent ingestion of MAO inhibitors and tyramine-containing foods may lead to hypertensive crisis. Symptoms include chest pain, severe headache, nuchal rigidity, nausea and vomiting, photosensitivity, and enlarged pupils. Treatment includes IV phentolamine.

Potential Nursing Diagnoses

• Ineffective coping (Indications)
• Risk for injury (Side Effects)
• Deficient knowledge related to disease processes and medication regimen (Patient/Family Teaching)

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. Patients receiving MAO inhibitors should also avoid OTC drugs and foods or beverages containing tyramine (see Food Sources for Specific Nutrients) during and for at least 2 wk after therapy has been discontinued, as they may precipitate a hypertensive crisis. A health care professional should be contacted immediately if symptoms of hypertensive crisis develop.
• 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 professional if dry mouth, urinary retention, or constipation occurs. Frequent rinses, good oral hygiene, and sugarless candy or gum may diminish dry mouth. An increase in fluid intake, fiber, and exercise may prevent constipation.
• Advise patient to notify health care professional of medication regimen and any herbal alternative therapies before treatment or surgery. MAO inhibitor therapy usually needs to be withdrawn at least 2 wk before use of anesthetic agents.
• Emphasize the importance of participation in psychotherapy and follow-up exams to evaluate progress.

Evaluation/Desired Outcomes

• Resolution of depression.
• Decrease in anxiety.
• Control of bedwetting in children over 6 yr of age.
• Management of chronic neurogenic pain.