To our knowledge, this is the first review to compare publicly available guidelines for the management of illicit drug-related ED presentations in Australia, the UK and the US with current treatments employed in EDs as reported in pertinent literature.

Among the five Australian papers,^{15,27–29,32} only one focused on identifying opportunities for implementing early interventions to prevent substance-induced psychosis. ²⁸ Another ²⁷ reported on use of oral or parenteral BZDs and antipsychotics in line with Australian guidelines (Table 1), without specifying individual medications. The remaining three papers reported using restraints as one of the interventions.

Unadkat et al. (2019) reported use of physical and mechanical restraints in over half of the methamphetamine-related ED presentations. ²⁹ The appropriateness was difficult to assess as pharmacological interventions and other de-escalating strategies were not reported. Tucker et al. (2016) reported a case of use of ziprasidone, oral lorazepam, droperidol, zuclopenthixol acetate, chlorpromazine and benztropine, ³² with only droperidol concordant with Australian guidelines.^16–18 This patient had a complex treatment history and therefore the use of lorazepam and zuclopenthixol may be justified. Benztropine was also administered to minimize extrapyramidal side effects. ³² The only Australian literature to report use of verbal de-escalation was the transcript of evidence from the Western Australian Parliament. ¹⁵

Even though five European studies^30,33–36 were included in this review, only UK guidelines could be sourced.^19,20 Hence, the appropriateness of reported interventions in these studies may not be fully determined. Both UK guidelines recommended non-restrictive de-escalation strategies, use of BZDs (lorazepam, midazolam or diazepam), antipsychotics (haloperidol, droperidol, olanzapine) and ketamine. Medications reported in the European studies were from the same classes as UK guidelines and antidotes prescribed for substance overdose were appropriate for intoxicated individuals.^34,36 However, the latter were not included in the UK guidelines. Restrictive interventions were not reported in the European studies,^30,33–36 potentially due to lack of recording.

A US case study ³⁷ reported use of risperidone, lorazepam, and both physical and mechanical restraints for cannabis-induced acute psychosis. While use of oral risperidone and lorazepam adhered to guidelines,^24,26 recommended oral medications for agitation induced by CNS depressant intoxication were first-generation antipsychotics, such as haloperidol. ²⁴ Lack of reporting on de-escalation strategies makes it challenging to comment on the use of restraints. Lastly, Finkelstein et al. (2017) reported use of BZDs, antipsychotics and other medications as well as supportive therapies like antidotes, anticonvulsants and ventilatory support. ³¹ However, the latter were not recommended in US guidelines, despite specific sections addressing substance intoxication.^21–25

All guidelines recommended BZD use (Table 1) although the preferred initial approach for agitation and aggression were verbal and other de-escalation strategies, including offering food and reducing environmental stimulation (Table 1). Restraints were frequently reported as a non-pharmacological intervention,^15,29,32,37 despite guidelines advising their use as last resort when there is risk of harm to self or others. Despite non-coercive de-escalation strategies being recommended as first line, they were only reported in the transcript of evidence. ¹⁵ It is uncertain whether restraints were considered after other attempts to de-escalate were ineffective or used incorrectly, or not reported as they were not considered as interventions. Hence, the prevalence of verbal de-escalation and its role in the clinical setting remains unclear.

Ventilatory support and antidotes were also commonly reported. Antidotes essential for intoxicated individuals were not recommended in any guidelines. Urine drug screens may lack accuracy and speed for rapid decision making in EDs,^38,39 but could be useful for those acutely psychotic, or unable to provide a reliable history. ⁴⁰