Tricyclic antidepressants - Amitriptylline

Question 1

What are indications for the use of tricyclic antidepressants?

Answer 1

• Moderate-to-severe depression where SSRI’s are ineffective
• Neuropathic Pain

Question 2

What is the mechanism of action of Tricyclic antidepresants?

Answer 2

Inhibit neuronal reuptake of serotonin (5HT) and noradrenaline from the synaptic cleft, thereby increasing their availibility for neurotransmission. This improvees mood and physical symptoms in depression and pain.

Question 3

Why do Tricyclic antidepressants have a wide array of side effects?

Answer 3

They act on muscarinic, histamine (H1), α-adrenergic (α1 and α2) and dopamine (D2) receptors

Question 4

What are important adverse effects of tricyclic anti-depressants?

Answer 4

• Antimuscarinic - dry mouth, constipation, urinary retention, blurred vision
• H1 and a1 - sedation, hypotension
• Arrythmias
• Long QT
• Convulsions
• Hallucinations
• Mania
• Dopamine - breast changes, sexual dysfunction, extrapyramidal effects
• Overdose

Question 5

What are features of TCA overdose?

Answer 5

• Hypotension
• Arrythmias
• Convulsions
• Coma
• Respiratory failure

Question 6

What can happen with sudden withdrawal of TCAs?

Answer 6

• GI upset
• Flu-like symptoms
• Sleep disturbance
• Neurological symptoms

Question 7

What should you never give with TCAs?

Answer 7

MOAIs - can precipitate hypertension and hyperthermia or serotonin syndrome

Question 8

What dose of amitriptylline would you start someone on for neuropathic pain?

Answer 8

10mg

Question 9

What advise would you give someone who you had prescribed a TCA?

Answer 9

• Symptoms will improve over a few weeks
• Mood - take drugs for at least 6 months
• Don’t stop taking it suddenly