Amitriptyline

Amitriptyline (or Amitryptyline) hydrochloride (sold as Elavil, Tryptanol, Endep, Elatrol, Tryptizol, Trepiline, Laroxyl) is a tricyclic antidepressant drug. It is a white, odorless (but tastes like licorice), crystalline compound which is freely soluble in water; it is usually dispensed in tablet form. In terms of its mechanism of action, amitriptyline inhibits serotonin and noradrenaline reuptake almost equally.

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Uses

Approved

Amitriptyline is approved most commonly for the treatment of depression (clinical/endogenous depression, also involutional melancholia 'depression of late life', which is no longer seen as a disease in its own right). Adult typical dosages are 25 to 150 mg daily, with half this initially for elderly or adolescents.

It may also be used to treat nocturnal enuresis (bed wetting). Children between the ages of 7 to 10 years having a dose of 10 to 20 mg, older children 25 to 50 mg at night. It should be gradually withdrawn at the end of the course, which overall should be of no more than 3 months.^[1]

In some European countries it is also officially approved as a preventative (prophylaxis) for patients with frequent/chronic migraines, usually 2.5 to 75 mg.

Unapproved/Off-Label/Investigational

Amitriptyline may be prescribed for other conditions such as insomnia, migraine, rebound headache, chronic pain, chronic cough, postherpetic neuralgia (persistent pain following a shingles attack), carpal tunnel syndrome, fibromyalgia, vulvodynia, interstitial cystitis, irritable bowel syndrome, diabetic peripheral neuropathy, neurological pain, and painful paresthesias related to multiple sclerosis and at low doses as a preventative (prophylaxis) for patients with frequent migraines.^[2] Typically lower dosages are required for pain modification of 10 to 50 mg daily.^[1]

Amitriptyline in low doses is also sometimes prescribed to help ease the symptoms of chronic fatigue syndrome. It is thought to help combat symptoms of insomnia primarily, in addition to other selected symptoms of the affliction.

A randomized controlled trial published in June 2005 found that amitriptyline was effective in functional dyspepsia refractory to famotidine and mosapride combination therapy.^[3]

Side effects

Common side effects of using amitriptyline are dry mouth, extreme weight gain, drowsiness, nervousness, dizziness, blurred vision and insomnia. Some rare side effects include tinnitus, hypotension, mania, psychosis, anticholinergic effects, heart block, arrhythmias, extrapyramidal symptoms, depression, and hepatic toxicity.

Overdose

The symptoms and the treatment of an overdose are largely the same as for the other tricyclic antidepressants.

Further information: Tricyclic antidepressant#Overdose

References

• PubChem Substance Summary: Amitriptyline National Center for Biotechnology Information.
• TREPILINE®-10 TABLETS; TREPILINE®-25 TABLETS South African Electronic Package Inserts. 12 May 1978. Revised February 2004.
• SAROTEN® RETARD 25 mg Capsules; SAROTEN® RETARD 50 mg Capsules South African Electronic Package Inserts. December 1987. Updated May 2000.
• AMITRIP® Amitriptyline hydrochloride 10 mg, 25 mg and 50 mg Capsules Medsafe NZ Physician Data Sheet. November 2004.
• [1] Consumer Medicine Information, Australia December 2005.
• MedlinePlus Drug Information (US National Institutes of Health), January 2008.