Diazepam i.m. - the Most Common, but Inappropriate Medication for Management of Acute Anxiety, Agitation and Aggression

Introduction: There is a need for intramuscular (IM) administration of benzodiazepines for acute restlessness, anxiety and agitation. In the Czech Republic, diazepam is frequently used. The aim of this study was to determine the variability of serum diazepam concentrations after IM administration and evaluate its clinical effect. Methods: We included six men, who were administered 10 mg of diazepam IM in an outpatient setting. Measurements were carried out 30 minutes (T1), 4 (T2) and 24 hours (T3) after diazepam administration. The diagnosis was determined using the Mini-International Neuropsychiatric Interview, anxiety was quantified by the Hamilton Anxiety Rating Scale (HAMA). Results: The mean levels of diazepam in the serum were 14.6 ng/ml at T1 (after 30 minutes), 48.6 ng/ml at 4 hours and 28.7 ng/ml at 24 hours after administration. The values at T1 ranged from 0.5 ng/ml to 148.0 ng/ml. We found no relationship between the scores of HAMA and concentrations of diazepam. Anxiety decreased to normal values (HAMA < 13) at the time T1 in all patients. Conclusions: Concentrations of diazepam were lower 30 minutes after the administration than after 4 and 24 hours, respectively. We observed the largest variability in concentrations 30 minutes after the administration, when the concentrations between patients differed 280-times. This finding confirms international experience that IM diazepam administration should not be used. We discuss the differences between individual SPCs and guidelines that force inappropriate use of diazepam IM and do not permit other than off-label use of midazolam.