Tricyclic Antidepressants

  • Dangerous in overdose
  • Sedative
  • Older drugs, proven efficacy

Drugs in class

  • Clomipramine
    • very effective
  • Imipramine
    • less sedative
  • Lofepramine
    • not cardiotoxic in overdose, fewer side effects, insomnia
  • doxepin 
    • sedative – better for anxious patients

Uses

  • severe depression
  • Atypical facial pain 
  • Prophylaxis of panic attacks 
  • Phobic anxiety 
  • Obsessive Compulsive

Mechanism of Action

  • Block uptake 1 of monoamines into neurones 
  • A slow adaptive decrease in presynaptic amine receptor sensitivity

Side effects

  • May increase weight and appetite

Anticholinergic

  • Dry mouth
  • tachycardia
  • blurred vision
  • glaucoma
  • constipation
  • urinary retention
  • sexual dysfunction
  • Cognitive impairment
  • fine tremor

Antiadrenergic

  • drowsiness
  • postural hypotension
  • sexual dysfunction
  • cognitive impairment

Histamine

  • Drowsiness
  • Weight gain

Membrane stabilising

  • ECG changes
    • prolonged PR and QT
    • depressed ST segments
    • flattened T-waves
  • cardiac conduction defects
  • cardiac arrhythmias
  • epileptic seizures

Other

  • Rash
  • Oedema
  • leucopenia
  • elevated liver enzymes

Withdrawal

  • Nausea
  • anxiety
  • sweating
  • GI symptoms
  • insomnia

Contraindications

  • Epilepsy 
  • Recent MI
  • heart block 
  • mania 
  • Severe liver disease 
  • Porphyria

Interactions

 

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