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Tricyclic Antidepressants

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turlough's version from 2017-10-30 12:56

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9 uses of amitriptyline 1) Major depression. 2) Neuropathic pain. 3) Chronic pain. 4) Migraine prophylaxis. 5) Frequent tension headache prophylaxis. 6) PTSD. 7) Nocturnal enuresis. 8) IBS. 9) Fibromyalgia
What is the typical starting dose of amitriptyline for depression? 75 mg daily divided into 1-3 doses.
What is the typical starting dose of amitriptyline for nerve pain? 10-25 mg daily, typically taken once daily at night.
How does amitriptyline work? Amitriptyline functions as a serotonin-noradrenaline reuptake inhibitor (SNRI). It is stronger effects on the serotonin transporter than the noradrenaline transporter but its metabolite nortriptyline has very strong effects on the NA transporter.
Why are SSRIs preferred to amitriptyline? Although amitriptyline is more effective, SSRIs are preferred because they are safer.
3 contra-indications to the use of amitripyline 1) Hypersensitivity. 2) Heart disease. 3) Use of a MAOI (including use within the past 14 days).
Does food affect amitripyline absorption? No
Amitripyline is a major substrate of which enzyme? CYP2D6
Is amitriptyline a good choice for elderly patients? No. It is highly sedating, it can cause orthostatic hypotension and it has anti-cholinergic effects.
5 interactions with amitriptyline 1) Anticholinergics. 2) Antiarrhythmics and QT-prolonging agents. 3) Drugs that increase serotonin levels (e.g. SSRIs and MAOIs). 4) CYP2D6 inducers. 5) CYP2D6 inhibitors.
Explain the interaction between amitriptyline and antiarrhythmics/QT-prolonging agents Concurrent use increases the risk of cardiotoxicity e.g. QT prolongation and cardiac arrest
Side effects of amitriptyline Cardiac side effects = Tachycardia, cardiotoxicity, arrhythmias (TCA). Anti-cholinergic side effects = Dry mouth, urinary retention, blurred vision, constipation and sedation.
4 counselling points with amitriptyline 1) Avoid driving or operating machinery. 2) Avoid alcohol. 3) Avoid abrupt discontinuation. 4) It may take several weeks for amitriptyline to become effective.
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