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Lesson 5 of9
In Progress

First Generation Antipsychotics

Jimmy October 25, 2021

Butyrophenones

  • Mechanism
    • Dopamine receptor inhibition
DrugOnset (IM)Onset (IV)
Haloperidol 5-10 mg20-60 min3-5 min
Droperidol 5-10 mg15-30 min1-2 min
  • Effects
    • Reduces psychotic symptoms
  • Adverse Effects
    • QTc prolongation, sedation, dystonia, akathisia
      • Akathisia – restlessness 🡪 “worsening agitation” 
      • Dystonia – torticollis, tongue protrusion, laryngeal dystonia (respiratory sx, stridor, dysphagia)
  • Caution
    • Neuroleptic malignant syndrome, Parkinson’s disease
  • Controversies
    • How significant is the QTc prolongation? Studies show…4-8 ms
    • Combination therapy needed? 

Calver et al, 2015

  • ECG within 2 hours of droperidol in 1009 patients 
    • 1.3% of patients had abnormal QTc
    • Of the 13 patients, 7 had pre-existing prolongation or other causes
  • No cases of TdP

Harrigan et al, 2004

  • Open-label, randomized, parallel-group trial of 183 patients
  • Haloperidol increased QTc interval by 7.1 ms