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Ketamine versus benzodiazepines for severely agitated emergency department patients

Three Part Question

In [severely agitated adult emergency department patients], does [ketamine] or [midazolam or lorazepam] [have a shorter time to sedation]?

Clinical Scenario

A 25 year old male is brought into the emergency department by police profoundly agitated. You wonder whether ketamine will work faster than lorazepam or midazolam to treat the agitation.

Search Strategy

Medline using the OVID interface.

(emergency or Emergency Service, Hospital/ OR emergency or Emergency Service, Hospital/ OR (accident and emergency).mp) AND ( or Ketamine/ OR or Ketamine/) AND ( or Benzodiazepines/ OR or Midazolam OR or Midazolam/ OR or Lorazepam/ OR or Lorazepam/)

Search Outcome

165 papers found of which 163 irrelevant and 1 relevant that has not yet published results. The remaining paper is discussed below.

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Riddell J et al
98 acutely agitated patients who required chemical sedation for acute agitation in ER. Ketamine (24) vs. Midazolam (17) vs. Lorazepam (33) vs. Haloperidol (14) vs. Combo (10)Prospective, observational studyTime to adequate sedationKetamine 6.57 mins vs. Midazolam 14.95 mins vs. Lorazepam 17.73 mins vs. Haloperidol 13.43 mins vs. Combo 23.30 mins (p<0.107)Single centre study, high proportion of methamphetamine abusers, not possible to randomize, physicians not blinded to medications received, dosing was not uniform, small sample size


There are an abundance of pre-hospital studies that cover the use of ketamine as a treatment for severe agitation, but a paucity of studies covering it’s use in the emergency department. The only current study available that compares ketamine to benzodiazepines in the emergency department is non-randomized. There is an RCT currently in progress, with results not yet published.

Clinical Bottom Line

There is insufficient robust evidence to recommend ketamine over midazolam or lorazepam for faster time to sedation in severely agitated emergency department patients. Further research on the topic is required before recommendations can be made.


  1. Riddell J; Tran A; Bengiamin R; Hendey GW; Armenian P. Ketamine as a first-line treatment for severely agitated emergency department patients. American Journal of Emergency Medicine 35(7):1000-1004, 2017 Jul.