Home Drug Guide Amitriptyline Hydrochloride

Drug Guide

Generic Name

Amitriptyline Hydrochloride

Brand Names Elavil, Endep, Amitril, Amitid

Classification

Therapeutic: Antidepressant, Tricyclic

Pharmacological: Serotonin-Norepinephrine Reuptake Inhibitor (SNRI)

FDA Approved Indications

Depressive disorder (major depression)
Prevention of migraine headaches
Chronic pain management (e.g., neuropathic pain)
Insomnia (off-label)

Mechanism of Action

Amitriptyline inhibits the reuptake of serotonin and norepinephrine, increasing their levels in the synaptic cleft, which enhances neurotransmission and alleviates depressive symptoms. It also has anticholinergic and antihistaminic properties.

Dosage and Administration

Adult: Typically 25-50 mg at bedtime, titrated up to 150-300 mg/day as needed.

Pediatric: Not generally recommended for children.

Geriatric: Start at lower doses (e.g., 10-25 mg at bedtime) due to increased sensitivity and risk of side effects.

Renal Impairment: Use with caution; dose adjustments may be necessary.

Hepatic Impairment: Use with caution; consider lower doses.

Pharmacokinetics

Absorption: Well absorbed orally.

Distribution: Widely distributed; crosses the blood-brain barrier.

Metabolism: Hepatically metabolized primarily via CYP2D6, CYP1A2, and CYP3A4 enzymes.

Excretion: Excreted mainly in urine.

Half Life: Approximately 10-28 hours.

Contraindications

Use in patients with recent myocardial infarction, as it may cause arrhythmias.
History of hypersensitivity to amitriptyline.

Precautions

Suicide risk, especially in young adults and adolescents.
Caution in patients with seizures, glaucoma, urinary retention, or bipolar disorder.

Adverse Reactions - Common

Dry mouth (Frequent)
Drowsiness (Common)
Dizziness (Common)
Constipation (Common)
Weight gain (Common)

Adverse Reactions - Serious

Cardiac conduction abnormalities (arrhythmias) (Rare)
Serotonin syndrome (Rare)
Suicidal thoughts or behavior (Possible in young patients)

Drug-Drug Interactions

MAO inhibitors (risk of serotonin syndrome)
CNS depressants (additive sedative effect)
Anticholinergic drugs (anticholinergic toxicity)

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor mental health status, suicidal ideation, cardiac status, and baseline ECG if indicated.

Diagnoses:

Risk for injury due to orthostatic hypotension or sedation
Risk for injury due to anticholinergic effects

Implementation: Administer at bedtime to reduce sedation; gradually titrate dose; monitor for therapeutic effects and adverse effects.

Evaluation: Assess for improvements in depressive symptoms and pain; monitor for adverse reactions and toxicity.

Patient/Family Teaching

Take medication exactly as prescribed.
Do not stop abruptly to avoid withdrawal symptoms.
Be cautious of drowsiness and avoid operating machinery until response is known.
Report worsening depression or suicidal thoughts immediately.
Use caution when driving or engaging in hazardous activities.

Special Considerations

Black Box Warnings:

Increased risk of suicidal thoughts and actions in children, adolescents, and young adults with major depressive disorder and other psychiatric disorders.
Serious skin reactions (erythema multiforme, toxic epidermal necrolysis).

Genetic Factors: Metabolism greatly affected by CYP2D6 phenotype; poor metabolizers may have increased plasma levels.

Lab Test Interference: May affect blood glucose and other laboratory tests.

Overdose Management

Signs/Symptoms: Altered mental status, hallucinations, seizures, tachycardia, hypotension, arrhythmias, cardiac conduction delays, coma.

Treatment: Supportive care, activated charcoal, sodium bicarbonate for cardiac toxicity; specific antidote is not available.

Storage and Handling

Storage: Store at room temperature, 20-25°C (68-77°F).

Stability: Stable under normal storage conditions.