Abstract
The use of intramuscular midazolam for the sedation and agitation in patients with psychiatric illness has been increasing in Australia, given its supposed safety profile and a lack of other alternatives such as intramuscular lorazepam [1]. The advantages include a rapid onset of action of 15 min and a short half-life of 1–2.5 h; the disadvantages include anterograde amnesia and respiratory depression. There have been small case series describing the successful use of midazolam in psychotic patients with agitation [2, 3]. One study concluded that it was useful in the treatment of agitation, verbal abuse or aggression, without adverse effects despite over 500 doses of midazolam being administered [4].
We conducted a one year review on the use of intramuscular midazolam in a 30 bed acute inpatient general adult unit in Sydney, Australia. One hundred and thirteen patients (67 male; average age 35.1) had 122 admissions with an average admission length of 19.5 days. The most common diagnoses on admission were schizophrenia (20.3%), mania/hypomania (20.5%) and other psychotic disorders (23.0%).
Two hundred and twelve doses of intramuscular midazolam were given; most doses were 5 mg (48.1%) or 10 mg (49.5%). In 74.1% (157/212) of episodes, an antipsychotic was administered concurrently and 2.4% (5/212) were given a second benzodiazepine. The most frequent indications were agitation (28.8%), verbal aggression (37.7%) and physical aggression (14.6%). Overall, 84.4% (179/212) of episodes resulted in the settling of the patient. In the 162 episodes where midazolam and another medication was given, 142 (87.7%) resulted in the settling of the patient. In the 50 episodes of midazolam use alone, 37 patients (74%) were treated successfully. Adverse effects were documented in eight episodes (3.8%), with seven concerning excess sedation and one of urinary incontinence. None of the adverse effects required medical intervention.
This review suggests that midazolam may be useful in the treatment of the aggressive or agitated patient. Further prospective studies are needed to clarify the efficacy of intramuscular midazolam in comparison to other benzodiazepines, such as lorazepam. Given the retrospective nature of this review, rating scales were not used but would be useful in prospective studies. There were no fatal outcomes, but the rate of serious adverse effects, such as anterograde amnesia and respiratory depression, would also need to be explored in future studies.