Haloperidol is the mainstay of delirium treatment.8 Compared with atypical antipsychotics in delirium treatment, haloperidol doses < 3.5 mg/d have not been associated with an increase in extrapyramidal symptoms (EPS).9
Although not devoid of side effects, atypical antipsychotics are an alternative to haloperidol.8,10 This article briefly summarizes the current evidence on the use of atypicals for treating delirium.
Evidence for antipsychotics
Haloperidol has been the antipsychotic of choice for treating delirium symptoms. It is recommended by the Society of Critical Care Medicine7 and is regarded as safe, cost-effective, and efficacious for delirium5 despite a risk of dose-related EPS and potential cardiac conduction alterations.5,14
Risperidone is not indicated for treating delirium but is one of the most extensively studied atypical antipsychotic alternatives to haloperidol. Evidence consisting primarily of case reports has illustrated the potential efficacy of risperidone in treating delirium (Table 2).10,15-19
Clinical Point
In a small double-blind, randomized trial, risperidone was effective but not significantly more so than low-dose haloperidol
In 2004, Parellada et al17 observed significant mean improvements in all measures (Delirium Rating Scale [DRS], Mini-Mental State Exam [MMSE], positive subscale of the Positive and Negative Syndrome Scale [PANSS-P], and Clinical Global Impressions scale [CGI]) in 64 delirium patients treated with risperidone. In a 2004 double-blind trial of 28 delirium patients randomly assigned to risperidone or haloperidol, risperidone was effective but not significantly more efficacious than low-dose haloperidol for acute delirium treatment.18
Advantages of using risperidone include its lack of anticholinergic effects. Potential side effects include dose-related EPS and weight gain, which were observed in patients with schizophrenia and other psychotic disorders and dementia-related behavioral disorders.20,21
Olanzapine. Much like risperidone, olanzapine’s use in delirium is relatively well described in the literature (Table 3).22-24 In a randomized, placebo-controlled study comparing olanzapine with haloperidol, 175 patients were treated for 7 days with olanzapine, haloperidol, or placebo. Olanzapine and haloperidol showed significantly greater DRS score improvement than placebo.24 There was no difference between olanzapine and haloperidol outcomes; however, olanzapine showed significant improvement by days 2 and 3 compared with haloperidol. Haloperidol was associated with a significantly higher rate of dystonia compared with olanzapine.
Olanzapine carries a risk of anticholinergic effects. This can be a drawback, especially in patients such as Ms. B whose delirium has an anticholinergic component. Olanzapine is available in an IM formulation, which can be an advantage when addressing agitation and medical comorbidities of delirium.
Quetiapine. Case reports have suggested quetiapine is effective for delirium (Table 4).10,25-27 In a prospective, open-label trial, Sasaki et al26 treated 12 delirium patients with a single bedtime dose of quetiapine. All patients achieved remission within several days of beginning quetiapine, and the drug was well tolerated with no detected EPS or excessive sedation.
Clinical Point
Quetiapine reduced delirium duration and agitation in a small double-blind randomized trial of adult ICU patients
In 2010 Devlin et al27 reported on the efficacy and safety of quetiapine in a prospective double-blind, placebo-controlled study of 36 adult ICU patients. Compared with those receiving placebo, patients taking quetiapine had a statistically significant shorter time to first resolution of delirium, reduced duration of delirium, and less agitation as measured by the Sedation-Agitation Scale. Mortality, ICU length of stay, and incidence of QTc prolongation did not differ, but patients treated with quetiapine were more likely to be discharged home or to rehabilitation and to have more somnolence. Quetiapine’s side effect profile includes a low occurrence of EPS, sedation, and dose-related anticholinergic effects.25
Ziprasidone. The literature on ziprasidone for delirium so far is limited to a few anecdotal case reports (Table 5).28-31 In 2002, Leso and Schwartz28 successfully used ziprasidone to treat delirium in a patient with human immunodeficiency virus and cryptococcal meningitis. Ziprasidone was chosen for its lack of sedating effects and low EPS risk. The patient experienced significant clearing of his delirium and lowering of his DRS score. Ziprasidone eventually was discontinued because a fluctuating QTc interval associated with comorbid electrolyte imbalances—a potential drawback to ziprasidone.
In the case of Ms. B, ziprasidone appeared to be efficacious; however, improvement in her medical condition, rather than ziprasidone treatment, is the most likely explanation for the resolution of her delirium symptoms.
Aripiprazole. Alao et al30 reported on 2 delirium patients treated with 30 mg and 15 mg aripiprazole; improvement was monitored using the MMSE and DRS (Table 5).28-31 In both cases, confusion, disorientation, and agitation improved within 7 days of treatment. In the first case, the patient’s MMSE score improved from 5 to 28 and his DRS score decreased from 28 to 6. The second patient’s MMSE score improved from 7 to 27 and her DRS score went from 18 to 6.
Straker et al31 reported on 14 delirium patients treated with aripiprazole. Twelve patients had a ≥50% reduction in DRS, Revised-98 scores, and 13 showed improvement on CGI scores. The rate of adverse side effects was low. Three patients had prolonged QTc interval, but no patients developed arrhythmia or discontinued aripiprazole.
Atypical antipsychotics for delirium: A reasonable alternative to haloperidol?
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