Olanzapine overdose: a series of analytically confirmed cases

Olanzapine Pharmacokinetics: A Clinical Review of Current Insights and Remaining Questions

Olanzapine is one of the most widely used antipsychotics since its initial approval by the US Food and Drug Administration in 1996 and has undergone extensive pharmacokinetic study. Despite being utilized in clinical psychiatry for decades, there remain questions regarding the variety of available formulations, the utility of therapeutic drug monitoring, altered kinetic properties in special populations/medical illnesses, the use of high-dose olanzapine, and drug interactions, among many others. We performed a narrative literature review of olanzapine pharmacokinetics in June 2023 using the US National Library of Medicine's PubMed.gov resource (https://www.ncbi.nlm.nih.gov/pubmed) and Google Scholar. Herein, we review clinically relevant aspects of olanzapine pharmacokinetic data while highlighting knowledge gaps and potential areas of future study.

Olanzapine poisoning in patients treated at the National Poison Control Centre in Belgrade, Serbia in 2017 and 2018: a brief review of serum concentrations and clinical symptoms

Olanzapine is a thienobenzodiazepine class antipsychotic that strongly antagonises the 5-HT2A serotonin receptor, but acute poisonings are reported rarely. Symptoms of an overdose include disorder of consciousness, hypersalivation, myosis, and coma. Serum concentration higher than 0.1 mg/L is toxic, while concentration above 1 mg/L can be fatal. Here we report key data about 61 patients admitted to the National Poison Control Centre in Belgrade, Serbia over olanzapine poisoning in 2017 and 2018. The ingested doses ranged from 35 to 1680 mg, and time from ingestion to determination from two to 24 hours. In 34 patients olanzapine serum concentrations were in the therapeutic range and in 27 in the toxic range. In five patients they were higher than fatal, but only one patient died. The most common symptoms of poisoning were depressed consciousness (fluctuating from somnolence to coma), tachycardia, hypersalivation, hypotension, myosis, and high creatine kinase. All patients but one recovered fully after nonspecific detoxification and symptomatic and supportive therapy.

Hospital-treated deliberate self-poisoning patients: Drug-induced delirium and clinical outcomes

OBJECTIVE

Drug-induced delirium has been attributed to opioid, benzodiazepine, antipsychotic, antihistaminic and anticholinergic drug groups at therapeutic doses. Delirium also occurs in hospital-treated self-poisoning (at supra-therapeutic doses), although the causative drug classes are not well established and co-ingestion is common. We tested the magnitude and direction of association of five major drug groups with incident cases of delirium.

METHODS

A retrospective longitudinal cohort (n = 5131) study was undertaken of deliberate and recreational/chronic misuse poisoning cases from a regional sentinel toxicology unit. We described ingestion and co-ingestion patterns and estimated the unadjusted and adjusted odds for developing a drug-induced delirium. We also estimated the odds of drug-induced delirium being associated with three outcomes: intensive care unit admission, general hospital length of stay and discharge to home.

RESULTS

Drug-induced delirium occurred in 3.9% of cases (n = 200). The unadjusted odds ratios for development of delirium were increased for anticholinergics 10.79 (5.43-21.48), antihistamines 6.10 (4.20-8.84) and antipsychotics 2.99 (2.20-4.06); non-significant for opioids 1.31 (95% confidence interval = [0.81, 2.13]); and reduced for benzodiazepines 0.37 (0.24-0.58); with little change after adjustment for age, gender and co-ingestion. Delirium was associated with intensive care unit admission, longer length of stay and discharge destination.

CONCLUSION

Drug-induced delirium was uncommon in this population. Co-ingestion was common but did not alter the risk. In contrast to drug-induced delirium at therapeutic doses in older populations, opioids were not associated with delirium and benzodiazepines were protective. Drug-induced delirium required increased clinical services. Clinical services should be funded and prepared to provide additional supportive care for these deliriogenic drug group ingestions.

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.

The Use, Safety, and Efficacy of Olanzapine in a Level I Pediatric Trauma Center Emergency Department Over a 10-Year Period

OBJECTIVES

Olanzapine is a second-generation antipsychotic increasingly used in emergency medicine for many indications. Literature on its use in children is sparse. Our objectives were to describe the use, safety, and efficacy of olanzapine in pediatric emergency patients.

METHODS

A structured chart review was performed of patients 18 years old or younger receiving olanzapine from 2007 to 2016 in the emergency department of a pediatric level I trauma center.

RESULTS

A total of 285 children received olanzapine. Mean age was 16.4 years (range, 9-18 years); 121 were male (42.8%). Primary indications for olanzapine included agitation (n = 166, 58.3%), headache (n = 58, 20.4%), nausea/vomiting/abdominal pain (n = 37, 12.5%), unspecified pain (n = 20, 7%), and other (n = 4, 1.4%). Route of olanzapine administration was intramuscular (n = 160, 56%; median dose, 10 mg; range, 2.5-20), intravenous (n = 101, 36%; median dose, 5 mg; range, 1.25-5), and oral (n = 24, 8%; median dose, 10 mg; range, 5-10). For agitated patients, 28 (17%) received another sedative within 1 hour. For headache patients, 5 (8.6%) received another analgesic. For gastrointestinal complaints, 5 patients (13.5%) received another analgesic/antiemetic. Adverse respiratory events were hypoxia (pulse oximetry reading, in percentage, <92%; n = 7, 2.4%), supplemental oxygen placement (n = 9, 3.2%), and intubation (n = 2, 0.7%). No patient died or had a dysrhythmia. One patient experienced dystonia.

CONCLUSIONS

Olanzapine seems safe when used for a variety of conditions in pediatric emergency patients. It may be effective for acute agitation, primary headache, and gastrointestinal complaints.

Extended-release quetiapine overdose is associated with delayed onset of toxicity compared to immediate-release quetiapine overdose

OBJECTIVES

There are currently no studies comparing toxicity after extended-release (XR) and immediate-release (IR) quetiapine overdose. To compare the time course of toxicity of XR and IR quetiapine overdose.

METHODS

Retrospective analysis of toxicology unit consultations from July 2013 to April 2016. Information extracted included demographics, type of ingestion (IR, XR, mixed formulation, dose, tablet count, time to presentation, sedative co-ingestants), lowest Glasgow coma score (GCS), time to lowest GCS, fastest pulse, lowest systolic blood pressure, and time to recovery from sedation.

RESULTS

There were 256 presentations in 210 patients. Females 86% (n = 181), median age 30.5 years (IQR 23-43). Median quetiapine dose for the whole cohort was 2 g (IQR 1-5). Sedating co-ingestants were seen in 61% of presentations. Comparison of IR (n = 43) and XR quetiapine (n = 23) ingestions without sedating co-ingestants revealed a larger median ingested dose for XR formulation: 5.7 g versus 1.75 g (P = 0.004) and larger median tablet strength (XR 200 mg vs IR 100 mg, P < 0.001). Median time to lowest GCS: XR 7 h (IQR 4.9-11) versus IR 3.8 h (IQR 2.4-5.7), P < 0.001. Median time to peak pulse: XR 9 h (IQR 3-12) versus IR 2.5 h (IQR 1.5-5), P = 0.01. Median time to recovery from sedation: XR quetiapine 20 h (IQR 12-39) versus 12 h (IQR 5.5-22), P < 0.05. Median duration of intubation: XR 47 h versus 17 h for IR, P = 0.04).

CONCLUSION

XR quetiapine overdoses without sedating co-ingestants were associated with a doubling of time to peak sedation and pulse, and had longer recovery from sedation. The absence of sedation or tachycardia 12 h post-overdose of XR quetiapine seems a reasonable timeframe to rule out significant poisoning.

The antipsychotic story: changes in prescriptions and overdose without better safety

AIMS

Morbidity and mortality from drug overdose has decreased over three decades. This is credited to safer drugs and therefore better outcomes in overdose. We aimed to investigate changing prescriptions of antipsychotic medications and associated changes in antipsychotic overdoses over a 26-year period.

METHODS

All antipsychotic poisoning presentations to a tertiary referral toxicology unit between 1987 and 2012 were reviewed. Data were collected prospectively on demographics, ingestion information, clinical effects, complications and treatment. Rates of antipsychotic drug use in Australia were obtained from Australian government publications for 1990-2011 and linked to overdose admissions by postcode.

RESULTS

There were 3180 antipsychotic overdoses: 1235 first generation antipsychotics, 1695 'atypical' second generation antipsychotics and 250 lithium overdoses. Over 26 years, antipsychotic overdoses increased 1.8-fold, with first generation antipsychotics decreasing to one-fifth of their peak (≈80/year to 16) and second generation antipsychotics increasing to double this (≈160/year), olanzapine and quetiapine accounting for 78%. All antipsychotic overdoses had a median length of stay of 18.6 h, 15.7% admitted to intensive care unit, 10.4% ventilated and 0.13% died in hospital, which was the same for first generation compared to second generation antipsychotics. There was a 2.3-fold increase in antipsychotic prescriptions over the same period; first generation antipsychotics declined whereas there was a dramatic rise in second generation antipsychotics, mainly olanzapine, quetiapine and risperidone (79%).

CONCLUSION

Over 26 years there was an increase in antipsychotic prescribing associated with an increase in antipsychotic overdoses. Although the type of antipsychotics changed, the morbidity and mortality remained the same, so that antipsychotics are an increasing proportion of overdose admissions.

Overdose of atypical antipsychotics: clinical presentation, mechanisms of toxicity and management

Historically, treatment for schizophrenia focused on sedation. The advent of the typical antipsychotics resulted in treatment aimed specifically at the underlying disease, but these agents were associated with numerous adverse effects, and were not particularly effective at treatment of the negative symptoms of schizophrenia. As a result, numerous atypical agents have been developed over the past 2 decades, including several agents within the past 5 years. Overdose of antipsychotics remains quite common in Western society. In 2010, poison control centres in the US received nearly 43,000 calls related to atypical antipsychotics alone. Due to underreporting, the true incidence of overdose with atypical antipsychotics is likely much greater. Following overdose of an atypical antipsychotic, the clinical effects observed, such as CNS depression, tachycardia and orthostasis are largely predictable based on the unique receptor binding profile of the agent. This article, which focuses on the atypical antipsychotics commonly used in the treatment of schizophrenia, discusses the features commonly encountered in overdose. Specifically, agents that result in QT prolongation and the corresponding potential for torsades de pointes, as well as unique features encountered with the various medications are discussed. The diagnosis of this overdose is largely based on history. Routine use of drug screens is unlikely to be beneficial. The primary goal of management is aggressive supportive care. Patients with significant CNS depression with associated loss of airway reflexes and respiratory failure need advanced airway management. Hypotension should be treated first with intravenous fluids, with the use of direct acting vasopressors reserved for persistent hypotension. Benzodiazepines should be used for seizures, with barbiturates used for refractory seizures. Intravenous magnesium can be administered for patients with a corrected QT interval exceeding 500 milliseconds.

[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.

Increased risks of acute organ dysfunction and mortality in intensive care unit patients with schizophrenia: a nationwide population-based study

OBJECTIVE

To investigate the risks of acute organ dysfunction and death in intensive care unit (ICU) patients with schizophrenia.

METHODS

Using a retrospective matched cohort design, we compared 203 schizophrenic patients to 2036 demographically matched (1:10) nonschizophrenic patients with first-time ICU admission between 2005 and 2007 using the claims data of a nationally representative cohort from the Taiwan National Health Insurance Research Database. Definitions of schizophrenia and associated diagnoses were based on the codes of the International Classification of Diseases, Ninth Revision, Clinical Modification. Analyses were performed using univariate and multivariate analyses.

RESULTS

The median age of schizophrenic patients was 53 years; 61.1% were men. Schizophrenic patients were less likely to be hospitalized in a medical center and had fewer surgical conditions and principal cardiovascular diagnoses, but they had a higher prevalence of infection than nonschizophrenic patients. After controlling for the aforementioned baseline covariates, schizophrenic patients had a higher risk of acute organ dysfunction (adjusted odds ratio = 1.52, 95% confidence interval = 1.09-2.10). When individual organ systems were analyzed, they had a 47% higher risk of respiratory dysfunction, a 194% higher risk of renal dysfunction, and a 122% higher risk of neurological dysfunction than nonschizophrenic patients. Hospital mortality was also higher in schizophrenic patients than in nonschizophrenic patients (24.1% versus 14.4%, p < .001; adjusted odds ratio = 1.56, 95% confidence interval = 1.08-2.24).

CONCLUSIONS

Among ICU patients, schizophrenic patients were sicker, having a higher risk of acute organ dysfunction and death.

Olanzapine intoxication-related transient diabetes insipidus

Olanzapine is a second-generation atypical antipsychotic agent approved for the treatment of psychotic disorders and mania. The effects of olanzapine intoxication include central nervous system depression, hyperthermia, myosis, tachycardia, and orthostatic hypotension. Heretofore, only one case has been reported to develop polyuria after olanzapine overdose (560 mg). We describe a case that developed diabetes insipidus following massive olanzapine ingestion and returned to normal after desmopressin treatment.

Amisulpride overdose is frequently associated with QT prolongation and torsades de pointes

This study aimed to describe the effects of the antipsychotic amisulpride in overdose, including the frequency of QT prolongation and torsades de pointes. Cases of amisulpride overdose (>1 g) were recruited from 2 state poison centers and a tertiary toxicology unit over 5 years. A 1-page clinical research form was used to collect clinical information. Copies of all electrocardiograms were obtained. Electrocardiogram parameters (QRS and QT intervals) were manually measured as previously described, and plots of QT-heart rate (HR) pairs were compared with the QT nomogram. There were 83 patients with amisulpride overdoses with a median age of 29 years (interquartile range [IQR], 23-40 years), and 42 (51%) were female. The median dose ingested was 6 g (IQR, 3-13 g, range, 1.2-120 g). The median HR was 66 beats/min (IQR, 60-81 beats/min). Bradycardia occurred in 20 cases (24%), and hypotension in 19 (23%). From 440 electrocardiograms (average of 5 per case; range, 1-15), an abnormal QT-HR pair occurred in 61 cases (73%). Torsades de pointes developed in 6 cases (7%), with doses of 4, 4.6, 18, 24, 32, and 80 g. The patient taking 32 g died after a cardiac arrest. Widened QRS did not occur except transient rate-dependent bundle-branch block in 3 cases. There were significant associations of bradycardia, hypokalemia, and hypocalcaemia, with QT prolongation and torsades de pointes. Central nervous system effects were uncommon with coma in 7 cases, seizures in 2, and dystonic reactions in 2. Amisulpride overdose commonly causes QT prolongation, bradycardia, and hypotension. Torsades de pointes occurred commonly enough to suggest that amisulpride is highly cardiotoxic in overdose.

Relationship between abnormal pupillary reactivity and the outcome of a psychotropic drug overdose

OBJECTIVE

The association between abnormal pupil reactivity (abnormal) and the outcome among patients with psychotropic drug overdose (OD) was retrospectively investigated.

METHODS

The study included patients that had experienced an OD between January and December 2007. The subjects were divided into 2 groups, namely, abnormal and normal groups.

RESULTS

There were 12 subjects in the abnormal and 74 subjects in the normal group. Glasgow Coma Scale in the abnormal was significantly smaller that that in the normal group. An average quantity of ingested tranquilizer per subject in the abnormal was significantly larger that those in the normal group. However, the duration of admission and survival rates between the two groups were not significantly different.

CONCLUSION

The patients that experienced an OD, who demonstrated abnormal pupil reactivity, tended to have ingested larger amounts of drugs while also demonstrating severe unconsciousness. However, the patients with abnormal pupil reactivity had a favorable outcome.

Quetiapine overdose: predicting intubation, duration of ventilation, cardiac monitoring and the effect of activated charcoal

To investigate factors that predict the probability and duration of mechanical ventilation in quetiapine overdose, and if cardiac toxicity occurs, this cohort study involved 176 patients presenting to a toxicology unit on 286 occasions with quetiapine overdose. Patient demographics, dose, coingestants, single dose activated charcoal (SDAC) administration, requirement for and duration of mechanical ventilation and electrocardiogram parameters (heart rate, QT, QRS) were obtained. A fully Bayesian approach using logistic regression and time-to-event analysis was undertaken to investigate the relationship between predictor variables and the requirement for and duration of intubation. QT versus heart rate was plotted on a QT nomogram to investigate QT prolongation. The commonest clinical effects were central nervous system depression on 136 occasions (48%) and tachycardia (67%). There were no malignant arrhythmias and an abnormal QT occurred in only 24 admissions (8.4%), all with tachycardia. Hypotension (systolic blood pressure <90 mmHg) occurred on 35 occasions (12%). The logistic regression model supported dose and SDAC (<2 h) influencing the probability of intubation, but not age, sex, therapeutic use of quetiapine or coingestants. The probability of intubation was 10% after 2 g, 22% after 5 g, 37% after 10 g and 55% after 20 g and SDAC resulted in a reduced probability of intubation of 7% for 2 g ingestion. The median duration of ventilation was 22 h (interquartile: 19-28 h), which was not affected by SDAC. Ingested dose can inform early decision making about requirements for intensive care unit admission and intubation. SDAC seems to have only modest effects on outcomes but may be considered within 2 h for large ingestions. Electrocardiogram monitoring is unlikely to be necessary.

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.

Neuroleptic malignant syndrome developing after acute overdose with olanzapine and chlorpromazine

Neuroleptic malignant syndrome (NMS) is a relatively uncommon side effect that may develop after a recent increase in the therapeutic dose of an antipsychotic medication or the addition of a new agent in therapeutic doses.

CASE REPORT

We report a case of NMS developing in a 36-year-old female patient 2 days following deliberate self-poisoning with 30 x 10-mg olanzapine tablets, 7 x 100-mg chlorpromazine tablets and an unknown amount of escitalopram. These were the patient's own medications. She had not been taking these for several weeks. The patient initially presented with sedation from her overdose which resolved over the next 24 hours. Following this, over the subsequent 24 hours, she became progressively confused, ataxic, hypertonic, ferbrile and tachycardic, with marked lead pipe rigidity of the limbs. Head CT, lumbar puncture and septic screen were all negative. She was treated with intravenous midazolam infusion, nasogastrically administered bromocriptine, external cooling and was mechanically ventilated. She gradually improved over a period of 10 days, with residual confusion lasting another week, and was discharged well with no deterioration from her premorbid neurologic state.

CONCLUSION

To our knowledge, although there are numerous cases reported with therapeutic use, NMS has not been reported to develop following acute olanzapine overdose. Clinicians should be aware that this may be an uncommon side effect of antipsychotic medication.

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.