Efficacy and Tolerability of Atypical Antipsychotics in the Treatment of Delirium: A Systematic Review of the Literature.

Background: Although haloperidol is the most widely used drug in the treatment of delirium, evidence on the relevance of atypical antipsychotics (AAPs) is growing.

Objective: To review the literature on the efficacy and tolerability of AAPs in the treatment of delirium.

Methods: A systematic search of the literature published before April 2018 was performed on PubMed using the following search strings: "Delirium" and "Atypical antipsychotics", "Novel antipsychotics", "New antipsychotics", "Quetiapine", "Olanzapine", "Aripiprazole", "Risperidone", "Paliperidone", "Clozapine", "Asenapine", "Iloperidone", "Amisulpiride", "Ziprasidone", "Zotepine", "Sertindole", "Lurasidone" or "Perospirone".

Results: Twelve randomized controlled trials (RCTs) and 22 open trials were considered. Despite an overall lack of large-scale RCTs, there is some evidence supporting the efficacy of olanzapine and quetiapine in placebo controlled trials. In a recent and large RCT in elderly patients, risperidone and/or haloperidol were associated with a significantly worse outcome than placebo. While preliminary, the current comparative studies suggest that haloperidol and the AAPs olanzapine, quetiapine and risperidone are similarly effective, although treatment with AAPs is associated with a reduced incidence of extrapyramidal symptoms. Ziprasidone was not shown to be effective. No RCTs are available for other AAPs.

Conclusions: Although the current evidence of the efficacy and tolerability of AAPs in the treatment of delirium is limited and the heterogeneity of the data precluded a meta-analysis, olanzapine and quetiapine seem to be adequate alternatives to haloperidol, especially in patients who are vulnerable for extrapyramidal symptoms, who require sedation or who have a history of haloperidol intolerance. Evidently, larger-scale RCTs are urgently required.