Tricyclic antidepressants

Question 1

What is an example of a tricyclic antidepressant?

Answer 1

• Amitriptyline

Question 2

What is the method of action of a tricyclic antidepressant?

Answer 2

• Inhibits neuronal reuptake of serotonin and noradrenaline from the synaptic cleft
• Neurotransmitter more available
• Block muscarinic, histamine, alpha-adrenergic and dopamine receptors = side effects

Question 3

What are the indications for tricyclic antidepressants?

Answer 3

• 2nd line treatment for moderate/severe depression when SSRIs are ineffective
• Neuropathic pain

Question 4

What are the contraindications for tricyclic antidepressants?

Answer 4

• Elderly
• CV disease
• Epilepsy
• Constipation
• Prostatic hypertrophy
• ↑ intraocular pressure

Question 5

What are the side effects of tricyclic antidepressants?

Answer 5

• Dry mouth – blockage of anti-muscarinic receptors
• Constipation – blockage of anti-muscarinic receptors
• Urinary retention – blockage of anti-muscarinic receptors
• Sedation – blockage of histamine and α1 receptors
• Hypotension – blockage of histamine and α1 receptors
• Arrhythmias
• ECG changes (prolonged QT/QRS duration)
• Convulsions
• Hallucinations
• Mania
• Breast changes - blockage of dopamine receptors
• Sexual dysfunction - blockage of dopamine receptors
• Coma – in overdose
• Respiratory failure – in overdose
• GI upset – in sudden withdrawal
• Influenza like symptoms – in sudden withdrawal
• Sleep disturbances – in sudden withdrawal

Question 6

What drugs interact with tricyclic antidepressants?

Answer 6

• Monoamine oxidase inhibitors – both ↑ serotonin and noradrenaline levels so can cause hypertension/hyperthermia/serotonin syndrome
• Drugs with anti-muscarinic side effects – may ↑ side effects
• Drugs with sedative side effects – may ↑ side effects
• Drugs with hypotensive side effects – may ↑ side effects

Question 7

What organ eliminates tricyclic antidepressants?

Answer 7

Kidney

Question 8

What information should you give to a patient taking tricyclic antidepressants?

Answer 8

• May take up to a week to feel the effects of the medication
• Carry on with the treatment for at least 6 months after you feel better to stop the depression coming back
• Do not stop the medication suddenly as you will get withdrawal affects