386 Use of Quetiapine in the Emergency Department for Acute Agitation and Associated Physiologic Effects

Abstract

Agitation is commonly encountered in the emergency department (ED) and antipsychotics are frequently used for treatment. Quetiapine is a second generation antipsychotic (SGA) indicated for treatment of schizophrenia and bipolar mania. It is rarely used for acute agitation because of its blockade of alpha-receptors, which can lead to a drop in blood pressure (BP). Decreases in systolic BP, which have been previously reported prospectively in a pilot study of ED patients, are thought to be unrelated to dose. However, it is unknown if other factors such as alcohol or concomitant benzodiazepine use contribute to these observed decreases in BP. This study measured the association of dose, alcohol use, benzodiazepine use, and age on decreases in systolic BP in patients receiving quetiapine in the ED. This is a multicenter structured review of an historical cohort of patient visits over 7 years. Visits were included if quetiapine was administered and vital signs were obtained both before and within 4 hours after administration. Age, dose of quetiapine, use of benzodiazepines, and presence of alcohol (as measured by Breathalyzer) were utilized as predictor variables, with benzodiazepines/alcohol dummy-coded for inclusion into a multivariate linear regression model. Decreases in systolic BP were utilized as the dependent variable, and were measured within a particular patient so as to prevent any pre-dose differences among groups from skewing the results. During the study period quetiapine was administered on 117 patient visits to 109 unique patients at an average dose of 200 mg (72% male, average age 44, range 19-86). Alcohol intoxication was present in 17.1% of patients (average BAL 120 mg/dl). Benzodiazepines were used adjunctively in 12.8% of quetiapine patients with an average dose of 2.8 mg in lorazepam equivalents. Seventy-two patient visits met all inclusion criteria for further analysis. The average decrease in systolic blood pressure was 12.5 mm Hg, but the decrease was not related to age, dose, alcohol use, or benzodiazepine use (all P>.10). Four patients became hypotensive defined as SBP ≤ 95 mm Hg, with one of these patients being 77 years (the others were 40, 45 & 46) with doses of 100 mg, 600 mg, 100 mg and 600 mg, respectively. In these four patients, none were taking alcohol and only one (age 46) received adjunctive benzodiazepines. The drop in SBP was from 110 to 90 mm Hg in the 77-year-old, 118 to 80, 111 to 91, and 137 to 95 in the other three subjects. The rest of the subjects had relative drops in SBP, but not to the level what we defined as hypotensive. Fifteen (20.8%) patients had alcohol use and 0% became hypotensive. Eleven (15.3%) patients received adjunctive benzodiazepines and 9.1% (n=1) became hypotensive. None of the patients studied had an O2 sat drop below 92% after medication administration. Quetiapine is infrequently used in the ED for agitation. Most patients in the ED setting will have at least some decrease in blood pressure after administration of quetiapine, but it remains difficult to predict which patients will become hypotensive. Decreases in blood pressure appear to not be related to dose, alcohol use or adjunctive benzodiazepine use. Additional research is warranted to determine other contributing factors.