Amitriptyline

Antidepressant Drug

Drug class: Tricyclic Antiperessant Drug

Amitriptyline (ELAVIL)（中文：阿米替林）

Pronunciation

Amitriptyline 10mg

Amitriptyline 25mg

Common Strengths of Amitriptyline

Amitriptyline are available in the following strengths:

• 10 mg, 25 mg, 50 mg, 75 mg, 100 mg, 150 mg tablets

Drug Trade Names of Amitriptyline

ELAVIL

Drug Usage

• Primary use: Treatment of depression
• Other uses: Anxiety disorders, post-traumatic stress disorder (PTSD), chronic pain, migraine prevention, insomnia

Mechanism of Action

Amitriptyline works by increasing the levels of serotonin and noreinephrine in the brain, which helps regulate mood. It inhibits the reuptake of these neurotransmitters at the synaptic cleft.

Route of Administration

Oral

Dosages

For depression

• Initial dose 75 mg/day in divided doses, may increase to 150 mg/day.
• Maintenance dose 40 to 100 mg/day.

Side Effects

Frequency	Adverse reactions
Common	These side effects often improve as the body adjusts to the medication
	Dry mouth
	Drowsiness or sedation
	Dizziness
	Constipation
	Weight gain
	Increased appetite
	Headaches
	Nausea and vomiting
	Difficulty urinating
	Blurred vision
	Fatigue or tiredness
Serious	Allergic reactions: Signs include difficulty breathing, swelling of the face or throat, and hives.
	Neurological sympptoms: Such as confusion, hallucinations, seizures, or fainting.
	Liver problems: Indicated by yellowing of the skin or eyes, dark urine or abdominal pain.
	Suicidal thoughts or behavior: Particularly in younger individuals under 24 years old.
	Severe constipation or urinary retention.
	QT prolongation: This can lead to serious heart rhythm problems, especially in overdose situations.

Pharmacokinetics

• Absorption: Rapidly absorbed from the gestrointestinal tract
• Metabolism: Primarily in the liver via CYP2C19, CYP3A4, and CYP2D6
• Elimination: Mainly excreted in urine. The half-life of 10 to 28 hours, but clinical effects may last longer
• Onset time: 2 to 4 weeks for antidepressant effects, up to 6 weeks for pain relief

Drug Precautions

Pregnancy

Use only if clearly needed; potential risk to the fetus.

Breastfeeding

Excreted in breast milk; use with caution.

Children and Elderly

Not recommended for children under 12; lower doses for elderly.

Monitoring items

Blood pressure, heart rate, mental status, suicidal thoughts

Drug Interactions

Major Interaction

• CYP450 Enzyme Inhibitors: Drugs that inhibit cytochrome P450 enzymes, particularly CYP2D6 and CYP2C19, can increase the plasma levels of amitriptyline. Examples include fluoxetine and paroxetine, which can significantly raise amitriptyline levels and enhance its side effects.

Moderate Interactions

• Central Nervous System (CNS) Depressants: Combining amitriptyline with other CNS depressants (e.g., benzodiazepines, alcohol) can enhance sedation and increase the risk of respiratory depression.
• Anticholinergic Drugs: Medications such as diphenhydramine and oxybutynin may increase the risk of anticholinergic side effects when taken with amitriptyline, potentially leading to complications like hyperthermia.
• Topiramate: This anticonvulsant can increase amitriptyline levels, necessitating dosage adjustments.
• Cimetidine: This medication can also raise amitriptyline levels, increasing the risk of side effects.
• Certain supplements, like St. John’s Wort, can reduce the effectiveness of amitriptyline by decreasing its levels in the body.
• Grapefruit: may affect the metabolism of amitriptyline, potentially increasing its level.

FAQ

How Should I Take the Tablet?

Usually with food to reduce stomach upset. It's often taken at bedtime due to its sedating effects.

What Should I Avoid While Taking?

Avoid alcohol, driving or operating machinery until you know how the medication affects you.

What Happens if I Miss a Dose?

Take it as soon as you remember, unless it is almost time for your next dose. Never take a double dose to make up for a missed one.