Altered Mental Status from Olanzapine Overdose Treated with Physostigmine

The Use of Physostigmine in the Diagnosis and Treatment of Anticholinergic Toxicity After Olanzapine Overdose: Literature Review and Case Report

BACKGROUND

Second-generation antipsychotic agents are commonly used by clinicians for the treatment of various psychiatric and medical conditions. Despite their presumed safety, an overdose with olanzapine may lead to the development of anticholinergic toxicity. The anticholinergic toxidrome is characterized by both central and peripheral physical findings. Central anticholinergic syndrome, a term used to describe the symptoms that arise from reduced cholinergic activity in the central nervous system, is characterized primarily by signs and symptoms consistent with hyperactive delirium. Signs of peripheral anticholinergia include mydriasis and blurred vision, tremors, ataxia, fever/hyperthermia, flushed and dry skin, dry oral mucosa, decreased bowel sounds, constipation, and urinary retention, among other symptoms. In extreme cases, central anticholinergic syndrome can be associated with seizures, coma, respiratory failure, and cardiovascular collapse.

OBJECTIVE

To provide scientific evidence regarding the efficacy and safety of physostigmine use in cases of anticholinergic toxicity.

METHODS

We conducted a comprehensive review of the published literature on the symptoms, diagnosis, and treatment of anticholinergic toxicity.

RESULTS

Currently the recommended treatment for olanzapine overdose, as is the case of most severe anticholinergic toxicity cases, involves supportive care, along with cardiac, neurological, and respiratory status monitoring. In addition, we detail the symptoms characteristic of anticholinergic toxicity, using the case of a patient experiencing central anticholinergic syndrome after an overdose with olanzapine.

CONCLUSION

Physostigmine, a tertiary acetylcholinesterase inhibitor, can be used to assist in the both the diagnosis and management of severe anticholinergic toxicity associated with an olanzapine overdose, which might be applicable to the antimuscarinic toxidrome associated with the ingestion of agents with significant anticholinergic activity.

Acute Brain Failure: Pathophysiology, Diagnosis, Management, and Sequelae of Delirium

Delirium is the most common psychiatric syndrome found in the general hospital setting, with an incidence as high as 87% in the acute care setting. Delirium is a neurobehavioral syndrome caused by the transient disruption of normal neuronal activity secondary to systemic disturbances. The development of delirium is associated with increased morbidity, mortality, cost of care, hospital-acquired complications, placement in specialized intermediate and long-term care facilities, slower rate of recovery, poor functional and cognitive recovery, decreased quality of life, and prolonged hospital stays. This article discusses the epidemiology, known etiological factors, presentation and characteristics, prevention, management, and impact of delirium.

Adverse Drug Reactions in the Intensive Care Unit

Adverse drug reactions (ADRs) are undesirable effects of medications used in normal doses [1]. ADRs can occur during treatment in an intensive care unit (ICU) or result in ICU admissions. A meta-analysis of 4139 studies suggests the incidence of ADRs among hospitalized patients is 17% [2]. Because of underreporting and misdiagnosis, the incidence of ADRs may be much higher and has been reported to be as high as 36% [3]. Critically ill patients are at especially high risk because of medical complexity, numerous high-alert medications, complex and often challenging drug dosing and medication regimens, and opportunity for error related to the distractions of the ICU environment [4]. Table 1 summarizes the ADRs included in this chapter.

Delirium with anticholinergic symptoms after a combination of paliperidone and olanzapine pamoate in a patient known to smoke cannabis: an unfortunate coincidence

We report a case of delirium with anticholinergic symptoms in a 19-year-old female patient with schizophrenia. On the day the symptoms emerged, the patient received olanzapine long-acting injection and a higher dose of paliperidone. We observed symptoms ranging from confusion to delirium as well as some anticholinergic symptoms. The delirium lasted 24 hours and was managed by intravenous fluid substitution and oral benzodiazepines. Olanzapine pamoate, paliperidone and cannabis are central nervous system (CNS) depressants, and their combination can increase the risks of CNS depression. In this case report, we review the symptoms of delirium in a case of antipsychotic overdose and provide general guidelines for managing these symptoms. We also review possible complications in combined use of cannabis, olanzapine and paliperidone.

[Informed Consent and the Approval by Ethics Committees of Studies Involving the Use of Atypical Antipsychotics in the Management of Delirium]

INTRODUCTION

Delirium is an acute alteration of consciousness and cognition. Atypical antipsychotics (AA) have recently become a main part of its treatment. Studies in this population generate a series of ethical dilemmas concerning the voluntary participation of patients and their state of vulnerability since their mental faculties are, by definition, compromised.

OBJECTIVE

To assess whether studies with AA for the treatment of delirium obtained an approval by an ethics committee on human research (ECHR), if an informed consent (IC) was obtained, whether the IC was verbal or written, and who gave the approval to participate.

METHOD

Systematic review of Medline for studies of delirium where quetiapine and olanzapine were the main treatment, assessing the existence of an ECHR approval and implementation of an IC.

RESULTS

11 studies were identified (6 of quetiapine and 5 of olanzapine). 5 had an ECHR approval.

CONCLUSIONS

Most studies examining the treatment of delirium with quetiapine or olanzapine were not subject to approval by an ECHR and most of them did not obtain an IC from the patient's legal guardian. It is essential that future studies of antipsychotics and other drugs for the treatment of delirium have the protocol approved by an ECHR and a written IC signed by the patient's legal representative, since by definition delirium is a condition that compromises superior mental processes.

Timing and frequency of physostigmine redosing for antimuscarinic toxicity

We sought to determine how frequently antimuscarinic-poisoned patients receiving physostigmine receive multiple doses of physostigmine, the length of time between physostigmine doses, and what impact multiple doses of physostigmine have on the disposition and total length of hospital stay. We performed a retrospective chart review of patients given physostigmine for likely antimuscarinic toxicity. A total of 45 patients met inclusion criteria. We abstracted patient demographics, vital signs, physical exam findings, electrocardiograms, the timing and dose of physostigmine, the implicated antimuscarinic agents, and disposition from the hospital. We counted the number of patients who required multiple physostigmine doses and calculated the time to repeat dosing. Fourteen of the 45 patients (31%) given physostigmine for antimuscarinic toxicity received multiple doses: nine patients (20%) received two doses, three patients (6.6%) received three doses, and two patients (4.4%) received four doses. Less than 5.5 h elapsed between sequential physostigmine doses, and less than 6.5 h elapsed between the first and last dose. Forty-five percent of patients receiving one dose of physostigmine were discharged from the emergency department (ED) and 36% of patients receiving more than one dose of physostigmine were discharged from the ED. Whether admitted or discharged, there was no statistically significant difference in the length of hospital stay between patients receiving one or multiple doses of physostigmine. Repeated physostigmine administration is not frequently needed in medication-induced antimuscarinic toxicity. Patients are not likely to require further physostigmine redosing more than 6.5 h from their first dose.

A systematic review of cardiovascular effects after atypical antipsychotic medication overdose

As the use of atypical antipsychotic medications (AAPMs) increases, the number of overdoses continues to grow. Cardiovascular toxicity was common with older psychiatric medications but seems uncommon with AAPM. We conducted a systematic literature review to describe the cardiovascular effects reported after overdose of 5 common AAPM: aripiprazole, olanzapine, quetiapine, risperidone, and ziprasidone. We included case reports and case series describing overdose of these 5 medications identified in a search of MEDLINE, EMBASE, and abstracts from major toxicology meetings. We found 13 pediatric cases (age, <7 years), 22 adolescent cases (age, 7-16 years), and 185 adult cases. No pediatric case described a ventricular dysrhythmia or a cardiovascular death. In the adolescent and adult cases, we found numerous reports of prolonged corrected QT interval and hypotension, but there were only 3 cases of ventricular dysrhythmia and 3 deaths that may have been due to direct cardiovascular toxicity. The results from case series reports were similar to the single case report data. Our review suggests that overdose of AAPM is unlikely to cause significant cardiovascular toxicity.

Pathoetiological model of delirium: a comprehensive understanding of the neurobiology of delirium and an evidence-based approach to prevention and treatment

Delirium is the most common complication found in the general hospital setting. Yet, we know relatively little about its actual pathophysiology. This article contains a summary of what we know to date and how different proposed intrinsic and external factors may work together or by themselves to elicit the cascade of neurochemical events that leads to the development delirium. Given how devastating delirium can be, it is imperative that we better understand the causes and underlying pathophysiology. Elaborating a pathoetiology-based cohesive model to better grasp the basic mechanisms that mediate this syndrome will serve clinicians well in aspiring to find ways to correct these cascades, instituting rational treatment modalities, and developing effective preventive techniques.

Delirium in the acute care setting: characteristics, diagnosis and treatment

Delirium is a neurobehavioral syndrome caused by the transient disruption of normal neuronal activity secondary to systemic disturbances. It is also the most common psychiatric syndrome found in the general hospital setting, its prevalence surpassing better known psychiatric disorders. This article reviews the published literature on delirium and addresses the epidemiology, known etiologic factors, presentation and characteristics of delirium, while emphasizing what is known about treatment strategies and prevention. Given increasing evidence that delirium is not always reversible and the many sequelae associated with its development, physicians must do everything possible to prevent its occurrence or shorten its duration, by recognizing its symptoms early, correcting underlying contributing causes, and using treatment strategies proven to help recover functional status.

Olanzapine overdose: a series of analytically confirmed cases

To describe the spectrum of clinical effects in olanzapine overdose and investigate the factors that predict severe outcomes. We analysed olanzapine-overdose events confirmed by drug analysis. Demographic, clinical and outcome data were recorded for each presentation. The relationship between dose and therapeutic olanzapine use, and outcomes (length of hospital stay, intensive care unit admission, mechanical ventilation, Glasgow coma score <9 and delirium) were investigated. Thirty-seven olanzapine overdose admissions were included. Median age was 30 years (interquartile range: 24-40 years), 24 women and 27 taking olanzapine therapeutically. Median ingested dose was 150 mg (range: 10-1600 mg). Olanzapine overdose was characterized by tachycardia (73%), central nervous system depression (43%), miosis (39%) and delirium (54%), which were either present on admission or developed within 6 h. There was no relationship between the dose and length of hospital stay, intensive care unit admission, Glasgow coma score <9 or delirium, but there was a trend towards more severe outcomes in patients not taking olanzapine therapeutically. Patients with delirium had an increased length of hospital stay and intensive care unit admission rate (50%) and 70% of them required physical or chemical restraint. Olanzapine overdose causes a high rate of delirium and central nervous system sedation that requires significant inpatient resources. Olanzapine overdoses should be initially observed for 6 h and patients not taking olanzapine regularly may have more severe effects.