drug adverse effects of tricyclic antidepressants

Adverse effects

• anticholinergic effects
  • tinnitus
  • constipation
  • confusion
  • mydriasis
  • tachycardia
    • amitriptyline > doxepin > nortriptyline > desipramine
  • in general, NOT a good class of agents for the elderly
• arrhythmic effects
  • overdose results in prolongation of the QT interval
  • patients with a bundle branch block are at higher risk
  • risk of torsades de pointes
  • avoid use within 6 months of coronary syndrome
  • avoid in patients with cardiovascular disease, arrhythmias
    • risk of arrhythmias, heart block, & sudden death
• cholinergic symptoms with abrupt withdrawal
  • abdominal cramping & diarrhea
• increased risk of seizures
• orthostatic hypotension
  • doxepin = amitriptyline > imipramine = nortriptyline > desipramine
• galactorrhea, hyperprolactinemia
• may trigger manic attack in patients with
  • bipolar affective disorder
  • schizoaffective disorder

Overdose:

• clinical manifestations
  • progressive somnolence, hypotension, widened QRS interval, seizures, & parasympatholytic signs (fever, tachycardia, mydriasis, diminished peristalsis)
  • case report of cardiac arrest in a young women
• management
  • early endotracheal intubation, hyperventilation
  • fluid resusitation
  • gastric lavage followed by activated charcoal even with delayed presentation
  • EKG monitoring: QRS complex > 100 msec predicts seizures
  • bicarbonate
    • bolus 1-2 meq/kg every 3-5 minutes until QRS complex narrows or blood pressure improves
    • bicarbonate drip titrated to QRS width & blood pressure
    • monitor serum K+, signs of fluid overload
  • norepinephrine for hypotension not responsive to bicarbonate
  • lidocaine for ventricular arrhythmias
  • benzodiazepines for seizures
    • avoid phenytoin
    • propofol or barbiturates for refractory seizures

More general terms

• drug adverse effect(s)