Quetiapine poisoning

Acute Quetiapine Intoxication: Relationship Between Ingested Dose, Serum Concentration and Clinical Presentation-Structured Literature Review and Analysis

Over the past decade, quetiapine has become one of the most commonly used psychotropic drugs in acute intoxication events worldwide. A structured literature review and analysis were conducted to assess the relationship between the kinetic and dynamic profiles in acute quetiapine intoxication. The correlation between dose and peak serum concentration (cmax) was determined using Pearson's correlation coefficient. Binary logistic regression was used to evaluate dose and cmax as predictors of the most common clinical events, signs and symptoms. One hundred and thirty-four cases of acute quetiapine ingestion were included in the analysis, with a median ingested dose of 10 g and a median cmax of 4 mg/L. The typical half-life was estimated to be 16.5 h, significantly longer than at therapeutic doses. For the immediate-release formulation, a biphasic disposition could not be excluded. Dose and cmax demonstrated a weak but significant correlation (r = 0.256; N = 63; p = 0.043). Central nervous system depression and tachycardia were the most common clinical signs. Higher doses and concentrations increased the risk of severe intoxication and were good predictors of intubation, tachycardia, hypotension, QTc prolongation and seizures, but not QRS prolongation, arrhythmia, heart block, hypokalaemia or acidosis. The thresholds for dose and cmax that increased the risk for individual signs and symptoms varied widely. However, doses > 3 g or cmax > 2 mg/L can be considered as alert levels that represent a high risk for severe clinical course of acute quetiapine intoxication.

Outcomes and Practices of Endotracheal Intubation Using the Glasgow Coma Scale in Acute Non-Traumatic Poisoning: A Systematic Review and Meta-Analysis of Proportions

BACKGROUND

Acute poisoning often results in decreased consciousness, necessitating airway assessment and management. Existing literature in the trauma setting suggests the importance of airway protection in unconscious patients to prevent complications, including aspiration. Practices for endotracheal intubation in non-traumatic acute poisoning are poorly described and variable, particularly regarding the use of a Glasgow Coma Scale (GCS) ≤ 8 threshold for intubation.

METHODS

A systematic review and meta-analysis of proportions was conducted to evaluate intubation rates and outcomes in patients presenting for acute non-traumatic poisoning. Studies were excluded if the primary indication for intubation was not airway protection. We analyzed rates of intubation, mortality, and aspiration by subgrouping patients into GCS ≤ 8, GCS 9-15, or mixed GCS. Common and random-effects analysis were used, supplemented by subgroup analyses.

RESULTS

39 studies were included in the analysis, involving 15,959 patients. Random-effects pooled intubation rates varied significantly across GCS categories: GCS ≤ 8 (30.0%, I2 = 92%, p < 0.01), GCS 9-15 (1.0%, I2 = 0%, p = 0.91), and mixed GCS (11.0%, I2 = 94%, p < 0.01), p-value <0.01 for subgroup difference. Aspiration rates also varied: GCS ≤ 8 (19.0%, I2 = 84%, p < 0.01), GCS 9-15 (4.0%, I2 = 78%, p < 0.01), and mixed group (5.0%, I2 = 72%, p < 0.01), p-value <0.01 for subgroup difference. Mortality rates remained low across all groups: GCS ≤ 8 (1.0%, I2 = 0%, p = 0.62), GCS 9-15 (1.0%, I2 = 0%, p = 0.99), and mixed group (2.0%, I2 = 68%, p < 0.01).

CONCLUSION

The conventional "less than 8, intubate" approach may not be directly applicable to acute poisoning patients due to heterogeneity in patient presentation, intubation practices, and low mortality. Therefore, a nuanced approach is warranted to optimize airway management strategies tailored to individual patient needs.

Quetiapine-Related Deaths: In Search of a Surrogate Endpoint

Quetiapine is a second-generation antipsychotic drug available for two and half decades. Due to increased misuse, prescription outside the approved indications, and availability on the black market, it is being encountered in medicolegal autopsies more frequently. For instance, it has been linked to increased mortality rates, most likely due to its adverse effects on the cardiovascular system. Its pharmacokinetic features and significant postmortem redistribution challenge traditional sampling in forensic toxicology. Therefore, a systematic literature review was performed, inclusive of PubMed, the Web of Science-core collection, and the Scopus databases; articles were screened for the terms "quetiapine", "death", and "autopsy" to reevaluate each matrix used as a surrogate endpoint in the forensic toxicology of quetiapine-related deaths. Ultimately, this review considers the results of five studies that were well presented (more than two matrices, data available for all analyses, for instance). The highest quetiapine concentrations were usually measured in the liver tissue. As interpreted by their authors, the results of the considered studies showed a strong correlation between some matrices, but, unfortunately, the studies presented models with poor goodness of fit. The distribution of quetiapine in distinct body compartments/tissues showed no statistically significant relationship with the length of the postmortem interval. Furthermore, this study did not confirm the anecdotal correlation of peripheral blood concentrations with skeletal muscle concentrations. Otherwise, there was no consistency regarding selecting an endpoint for analysis.

Adverse events with quetiapine and clarithromycin coprescription: A population-based retrospective cohort study

Background and Aims

Quetiapine is an atypical antipsychotic predominantly metabolized by the cytochrome P450 3A4 (CYP3A4) enzyme. We studied the risk of adverse events following coprescription of clarithromycin (a strong CYP3A4 inhibitor) versus azithromycin (not a CYP3A4 inhibitor) in quetiapine users.

Materials and Methods

This was a population-based retrospective cohort study from 2004 to 2020 in Ontario, Canada in adult quetiapine users newly co-prescribed clarithromycin (n = 16,909) or azithromycin (n = 25,267). The primary outcome was the composite of hospital encounters with encephalopathy (defined as a diagnosis of delirium, disorientation, transient alteration of awareness, transient ischemic attack, or unspecified dementia), a fall, or a fracture within 30 days of new coprescription. Secondary outcomes were individual components of the composite outcome, hospital encounter with computed tomography (CT) head scan, and all-cause mortality.

Results

Coprescription of clarithromycin versus azithromycin with quetiapine was associated with a higher risk of the primary composite outcome (365 of 16,909 clarithromycin users [2.2%] vs. 309 of 16,929 azithromycin users [1.8%]; absolute risk increase, 0.34% [95% confidence interval, CI, 0.04-0.63]; relative risk [RR], 1.19 [95% CI, 1.02-1.38]). This was primarily driven by an increase in fragility fractures (78 of 16,909 clarithromycin users [0.5%] vs. 45 of 16,923 azithromycin users [0.3%]; absolute risk increase, 0.20% [95% CI, 0.07-0.32]; RR, 1.74 [95% CI, 1.21-2.52]). Hospital encounters with a CT head scan were higher in clarithromycin users (220 of 16,909 [1.3%] vs. 175 of 16,923 azithromycin users [1.0%]; absolute risk increase, 0.27% [95% CI, 0.04-0.50]; RR, 1.26 [95% CI, 1.04-1.54]), but there was no difference in hospital encounters with encephalopathy, falls, or all-cause mortality between macrolide groups.

Conclusion

Among adults taking quetiapine, concurrent use of clarithromycin compared with azithromycin was associated with a small but statistically greater 30-day risk of a hospital encounter for encephalopathy, falls, or fracture, which was predominantly related to a higher rate of fragility fractures.

Dose-Dependent Biphasic Action of Quetiapine on AMPK Signalling via 5-HT7 Receptor: Exploring Pathophysiology of Clinical and Adverse Effects of Quetiapine

Recent pharmacological studies indicated that the modulation of tripartite-synaptic transmission plays important roles in the pathophysiology of schizophrenia, mood disorders and adverse reactions. Therefore, to explore the mechanisms underlying the clinical and adverse reactions to atypical antipsychotics, the present study determined the effects of the sub-chronic administration of quetiapine (QTP: 3~30 μM) on the protein expression of 5-HT7 receptor (5-HT7R), connexin43 (Cx43), cAMP level and intracellular signalling, Akt, Erk and adenosine monophosphate-activated protein kinase (AMPK) in cultured astrocytes and the rat hypothalamus, using ultra-high-pressure liquid chromatography with mass spectrometry and capillary immunoblotting systems. QTP biphasically increased physiological ripple-burst evoked astroglial D-serine release in a concentration-dependent manner, peaking at 10 μM. QTP enhanced the astroglial signalling of Erk concentration-dependently, whereas both Akt and AMPK signalling’s were biphasically enhanced by QTP, peaking at 10 μM and 3 μM, respectively. QTP downregulated astroglial 5-HT7R in the plasma membrane concentration-dependently. Protein expression of Cx43 in astroglial cytosol and intracellular cAMP levels were decreased and increased by QTP also biphasically, peaking at 3 μM. The dose-dependent effects of QTP on the protein expression of 5-HT7R and Cx43, AMPK signalling and intracellular cAMP levels in the hypothalamus were similar to those in astrocytes. These results suggest several complicated pharmacological features of QTP. A therapeutically relevant concentration/dose of QTP activates Akt, Erk and AMPK signalling, whereas a higher concentration/dose of QTP suppresses AMPK signalling via its low-affinity 5-HT7R inverse agonistic action. Therefore, 5-HT7R inverse agonistic action probably plays important roles in the prevention of a part of adverse reactions of QTP, such as weight gain and metabolic complications.

The serotonin toxidrome: shortfalls of current diagnostic criteria for related syndromes

INTRODUCTION

Serotonin syndrome (toxicity) describes adverse drug effects from toxic amounts of intra-synaptic central nervous system serotonin. A wide range of drugs have been implicated to cause serotonin toxicity, not all justifiably. The plausible agents all have a final common pathway resulting in a substantial increase in central nervous system serotonergic neurotransmission. Serotonin toxicity is characterized by neuromuscular excitation, mental status changes, and autonomic dysregulation. Signs and symptoms represent a spectrum of toxicity (mild to life-threatening) related to increasing serotonin concentrations. As there is no consensus on the threshold for "toxicity" or diagnostic criteria, the true incidence of serotonin toxicity is unknown. The incidence in overdose is easier to quantify and is reasonably common in serotonergic antidepressant overdoses. In a large case series of overdoses, moderate serotonin toxicity occurred in 14% of poisonings with a selective serotonin reuptake inhibitor. While half those ingesting a monoamine oxidase inhibitor in combination with a serotonergic agent in overdose exhibit at least moderately severe serotonin toxicity. In contrast, the incidence of serotonin toxicity in those on therapeutic serotonergic agents appears to be very low.

OBJECTIVES

To provide a narrative review of the current diagnostic criteria, utilizing case reports of fatalities to evaluate how many meet the various diagnostic criteria and propose practical solutions to resolve controversies in diagnosis.

METHODS

A review of serotonin toxicity diagnostic criteria in the English literature was completed by searching Embase and PubMed from January 1990 to July 2021 for the keywords "serotonin syndrome/toxicity" paired with "diagnostic criteria" or "diagnosis." Also, fatal cases of serotonin toxicity identified from a recent systematic review were independently examined to determine what diagnostic criteria were met and whether serotonin toxicity or another cause was most likely.

REVIEW OF DIAGNOSIS CRITERIA

Serotonin toxicity is a clinical diagnosis, four diagnostic criteria (Sternbach, Serotonin Syndrome Scale, Radomski, and Hunter) have been proposed. However, the Serotonin Syndrome Scale has not been validated in patients with serotonin toxicity and only utilized in those on a serotonergic agent. The remaining three criteria are utilized more widely but have undergone little refinement or validation.

REVIEW OF FATAL CASES

Shortfalls with diagnostic criteria can be illustrated by examining case fatalities. Of 55 fatal cases reviewed, 12 (22%) were unlikely to be serotonin toxicity. Sternbach and Radomski criteria were met by 25 (45%), 20 (36%) had insufficient data reported and 10 (18%) met an exclusion criterion. Few had sufficient information reported to determine whether Hunter Criteria were met, with only 13 (24%) documented as meeting the criteria, the remaining 42 (76%) had insufficient data.

RESOLVING SHORTFALLS IN CURRENT DIAGNOSTIC CRITERIA

As serotonin toxicity is a clinical diagnosis, issues arise when basing the diagnosis on symptom criteria alone, without considering whether the drug/s ingested increase central nervous system serotonin or whether there is an alternative diagnosis. This has resulted in case reports and government warnings for drugs that cannot plausibly cause significant serotonin toxicity (e.g., ondansetron and antipsychotics). We propose when assessing for a serotonin toxidrome, both the causative agent(s) and clinical scenario is considered to determine the likelihood of serotonin toxicity. Then the clinical features assessed, those with a moderate to high prior probability (e.g., serotonergic drug-drug interaction, overdose, recent initiation or increase in dose of serotonergic agent/s) could be diagnosed based on the Hunter criteria. However, those with a low probability (e.g., stable therapeutic doses of a serotonergic agent) require more specific and stringent criteria. Finally, we propose a minimum dataset for case reports/series of serotonin toxicity.

CONCLUSIONS

More complete and accurate reporting of serotonin toxicity cases is required in the future, to avoid further misleading associations that are physiologically implausible.

Cardiopulmonary Arrest Following a Single 25 Mg Dose of Quetiapine: A Case Report

Introduction

Quetiapine is commonly used in intensive care units (ICU) to treat delirium. Cardiopulmonary arrest caused by low dose quetiapine is unreported. Only two cases in the literature have reported acute respiratory failure after single doses of 50mg and 100mg respectively. We report a case of cardiopulmonary arrest in a patient after the administration of a single 25mg dose of quetiapine.

Case presentation

A 72-year-old Chinese female with multiple cardiovascular co-morbidities was admitted to the ICU intubated, following complications from an elective endovascular repair of an infrarenal abdominal aortic aneurysm. She was alert and extubated the following day. She subsequently showed signs of delirium and was administered a single 25mg dose of oral quetiapine. Seven hours after ingestion, she developed type 2 respiratory failure and eventually cardiopulmonary arrest. She was successfully resuscitated and other causes for cardiopulmonary arrest were excluded. Twenty-four hours following her cardiopulmonary arrest, her respiratory failure had completely reversed and she was extubated uneventfully.

Conclusion

This case report demonstrates that a single dose of oral quetiapine 25mg is sufficient to cause respiratory failure and cardiopulmonary arrest. Caution is advised when prescribing quetiapine in the elderly, especially in those with impaired drug clearance.

Angiotensin axis antagonists increase the incidence of haemodynamic instability in dihydropyridine calcium channel blocker poisoning

CONTEXT

Amlodipine, a dihydropyridine calcium channel blocker (CCB), is the leading cause of cardiovascular drug-related overdose deaths in the USA. In contrast, angiotensin-II receptor blockers (ARBs) and angiotensin converting enzyme inhibitors (ACEIs) cause minimal toxicity in overdose. ACEIs/ARBs are often combined with dihydropyridines in hypertension treatment. Co-ingested ARBs/ACEIs may significantly contribute to the toxicity of dihydropyridine, but this has not been investigated.

OBJECTIVE

To investigate the clinical outcomes from dihydropyridine overdoses with ARBs/ACEIs versus dihydropyridine overdoses alone.

METHODS

This was a retrospective study of patients reported to the New South Wales Poisons Information Centre (NSW PIC) and 3 toxicology units (Jan 2016 to Jun 2019) in Australia. Patients >14 years who took an overdose of dihydropyridines (amlodipine, felodipine, lercanidipine, nifedipine) were included. Concurrent overdoses with non-dihydropyridine CCBs, alpha-blockers and beta-blockers were excluded. Patient demographics, drugs exposure details, serial vital signs, treatments and outcome were collected.

RESULTS

There were 100 patients. 68 took mixed overdoses of dihydropyridines with ARBs/ACEIs and 32 took single overdoses of dihydropyridines without ARBs/ACEIs. The mixed group had lower median nadir mean arterial pressures (62 vs 75 mmHg, p < 0.001), more frequently had hypotension (OR 4.5, 95%CI: 1.7-11.9) or bradycardia (OR 8.8, 95%CI: 1.1-70). Multivariable analysis indicated the mixed overdoses had an 11.5 mmHg (95%CI: 4.9-18.1) lower minimum systolic blood pressure (SBP) compared with the single group; other factors associated with a lower minimum SBP were higher doses [2.3 mmHg (95%CI: 1.1-3.5) lower per 10 defined daily doses] and younger age [2.2 mmHg (95%CI: 0.3-4.2) higher per decade]. A larger proportion of the mixed ingestion group received intravenous fluids (OR 5.7, 95%CI: 1.8-18.6) and antidotes and/or vasopressors (OR 2.9, 95%CI: 1.004-8.6).

CONCLUSION

Combined overdoses of dihydropyridines with ARBs/ACEIs caused more significant hypotension and required more haemodynamic support than overdoses of dihydropyridines alone.

Quetiapine Poisoning and Factors Influencing Severity

PURPOSE/BACKGROUND

Quetiapine is a relatively new atypical antipsychotic with fewer adverse effects. It is increasingly prescribed to patients. The purpose of this study was to describe the cases of poisoning observed at the western France Poison Control Centre and identify potential risk factors that increase the severity of the cases.

METHODS

This was a retrospective study of self-poisoning with quetiapine as reported by the western France Poison Control Centre between 2007 and 2017.

RESULTS

There were 372 cases of quetiapine poisoning. Circumstances are known in 367 of 372 cases. There were 75 cases of null severity (grade 0), 133 cases of mild severity (grade 1), 85 cases of moderate severity (grade 2), and 79 cases of high severity (grade 3). Five deaths were listed in this series. The most commonly observed symptoms were neurological and cardiovascular in nature (drowsiness, coma, tachycardia, hypotension). Of these cases, 79.8% included voluntary ingestions. Among 302 cases with coagents, the most common coagents were benzodiazepines (56%), other psychotropic drugs (41%), and antidepressants (37%). An evaluated ingested dose 1500 mg or greater and 2 or more coagents increase the risk of severe poisoning. In particular, concomitant ingestion of benzodiazepines and antidepressants with quetiapine was associated with high severity (odds ratio, 2.478 [confidence interval, 1.3-4.723]; odds ratio, 1.820 [confidence interval, 1.010-3.316]).

CONCLUSIONS

Quetiapine may lead to severe poisoning for which there is currently no specific treatment. Patients and practitioners should be aware of this when quetiapine is prescribed, particularly when used in combination with other medications, and in order to deal with cases of poisoning.

Quetiapine dose optimisation during gestation: a pharmacokinetic modelling study

Objectives

The second-generation antipsychotic quetiapine has been demonstrated to undergo gestation-related changes in pharmacokinetics. This study applied pharmacokinetic modelling principles to investigate the mechanism of these changes and to propose new dosing strategies to counteract these changes.

Methods

A pharmacokinetic modelling approach was implemented using virtual population groups. Changes in quetiapine trough plasma concentration during gestation were quantified across all trimesters, and dose adjustment strategies were applied to counteract these changes by targeting a therapeutic range of 50–500 ng/ml throughout gestation.

Key findings

The application of the model during gestation predicted a decrease in trough concentration. A maximum decrease of 58% was predicted during trimester 2, and being associated with a statistically significant decrease in oral clearance at gestation week 25, 204 l/h ± 100.8 l/h compared with non-pregnant subjects, 121.9 l/h ± 51.8 l/h. A dosing optimisation strategy identified that dose increases to 500–700 mg twice daily would result in 32–55% of subjects possessing trough concentration in excess of 50 ng/ml.

Conclusions

Quetiapine doses in pregnancy should be increased to 500–700 mg twice daily to counteract a concomitant increase in metabolic clearance, increase in volume of distribution and decrease in plasma protein binding.

Use of a tablet-based application for clinical handover and data collection

Context: Inpatient toxicology services undertake remote as well as inpatient management of poisoned patients. The aim of this study is to describe the introduction of a tablet-based electronic data collection tool allowing data to be captured on inpatient and remote consultations.Methods: Retrospective review of all cases entered in the database from 1 March 2014 to 28 February 2016. Data collected included demographics (age, sex), clinical details (exposure category), presentation facility and disposition.Results: The database included 3616 cases: 59 (1.6%) were excluded due to inadequate details, 122 (3.4%) had no electronic medical record available, 1985 (54.9%) presented to the inpatient unit facility and 1450 (40.1%) were external consultations. Of these 1450, 223 (6.2%) were paediatric (aged less than 12 years), 395 (10.9%) adolescent (12-17 years) and 832 (23.0%) adults (18 years and over). The proportion of paediatric cases (median age 2 y; 45.7% females) with pharmaceutical ingestions was 122 (54.7%; 95% confidence intervals (CIs): 48.2-61.1) compared with 345 (87.3%; 95% CI: 83.7-90.3) in adolescents (median age 15 y; 79.5% females). Of the adult presentations, 659 (18.2%) were metropolitan/regional facility presentations and 173 (4.8%) rural facilities with 125 (3.4%) adults subsequently transferred to the inpatient facility. Median age was 38 years (interquartile range (IQR) 35-52) with 338 (51.4%) females in the metropolitan group and 37 years (IQR 26-48) with 51 (30.5%) females in the rural group. There were more bites and stings in the rural group, 41 (23.7%; 95% CI: 18.0-30.6) versus 54 (8.2%; 95% CI: 6.3-10.5), more recreational substance exposures 27 (15.6%; 95% CI: 11.0-21.8) versus 40 (6.1%; 95% CI: 4.5-8.2) and less pharmaceutical exposures 93 (53.8%; 95% CI: 46.3-61.0) versus 462 (70.1%; 95% CI: 66.5-73.5).Conclusions: The tablet based database provided useful information on populations of poisoned patients not accessible previously. It demonstrated important differences in the types of patients presenting to rural versus metropolitan hospitals.

Delirium Induced by Quetiapine and the Potential Role of Norquetiapine

Quetiapine in an atypical antipsychotic drug that is frequently used for delirium and behavioral and psychological symptoms in dementia. However, its potential anticholinergic effects, mediated primarily through its metabolite norquetiapine, could present as counterproductive adverse effects in these situations. There is little data published discussing this potential negative impact on quetiapine’s safety and tolerability, especially in the elderly. Here, we present what is, to our knowledge, the first published case report of delirium apparently induced by low-dose quetiapine, in a 95-year-old patient with no prior history of mental illness, and the potential role of its metabolite norquetiapine.

Treatment of Polypharmacy Overdose with Multimodality Extracorporeal Life Support

A 45-year-old woman presented to the emergency department of a tertiary referral hospital after taking an overdose of verapamil, doxepin, quetiapine, diazepam, temazepam, and clonazepam. She rapidly developed shock refractory to pharmacological support and was placed on percutaneous venoarterial extracorporeal membrane oxygenation (ECMO). She had a severe metabolic acidosis from a combination of shock and drug intoxication that improved with continuous venovenous haemodialysis. Forty-eight hours after presentation, while still on ECMO, the patient had complete cardiac standstill for three and a half hours, attributable to slow-release verapamil, that resolved after the commencement of plasmapheresis. The role of plasmapheresis in verapamil overdose requires further study.

Restarting antidepressant and antipsychotic medication after intentional overdoses: need for evidence-based guidance

Intentional drug overdoses with antidepressant and antipsychotic medications are an increasingly common problem. Currently, there is little guidance with regard to reintroduction of these medications after intentional overdoses. We have used published toxicological and pharmacokinetic data to obtain factors which control the recovery from overdoses. From such data, we have proposed guidance regarding their reintroduction, provided there are no adverse effects or contraindications. Tentatively, we suggest that when adverse effects from the overdose are lost, treatment could recommence after a further mean half-life of elimination. Most antidepressant and antipsychotic drugs are metabolized by cytochrome P450 enzymes and, where cytochrome P450 inhibitors are co-ingested, serial plasma concentrations should optimally be obtained in order to assess a suitable time for reintroduction of the psychoactive drugs. We hope the proposals presented will stimulate research and discussion that lead to better guidance for clinicians concerning reintroduction of psychoactive medication after intentional overdose.

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.

Delayed-Onset Seizure in a Mild Quetiapine Overdose: Report of a Case and Review of the Literature

Among atypical antipsychotics, quetiapine is commonly prescribed and considered to have a favorable side effect and safety profile. Here, we report the case of a patient who developed a generalized tonic-clonic seizure 28 hours following ingestion of 1,400 mg of quetiapine. Review of the literature identifies delayed-onset seizure as a potential complication of quetiapine overdose. Unique to this case, delayed-onset seizures occurred in a patient with a relatively low dose of quetiapine and no obvious toxidrome, suggesting that this reaction may be an important consideration in the management of quetiapine overdose. The pharmacokinetics and pharmacodynamics of quetiapine may explain this unusual phenomenon.

Overdoses with Aripiprazole: Signs, Symptoms and Outcome in 239 Exposures Reported to the Danish Poison Information Centre

The aim of this study was to characterize the clinical signs and symptoms of exposures to aripiprazole overdoses. We retrospectively identified all aripiprazole exposures reported to the Danish Poison Information Centre (DPIC) from June 2007 to May 2015. Information concerning demographics, ingested dose and symptoms was extracted from the DPIC database and medical records. Information on death and admission to hospital was obtained from Danish national registers. We analysed 239 cases, 86 concerning single-drug exposures to aripiprazole, and 153 cases where aripiprazole had been taken with at least one other substance (mixed-drug). The median ingested aripiprazole dose was 105 mg (IQR: 50-1680 mg) in the single-drug exposure group and 120 mg (IQR: 60-225 mg) in the mixed-drug exposure group. The most commonly reported symptom was light sedation, reported in 63% of the single-drug group and 50% of the mixed-drug exposure group. There were no malignant arrhythmias or ECG abnormalities after single-drug exposures. No deaths were recorded in relation to the intake. We found a long-term mortality rate of 13 deaths per 1000 person-years (95% CI: 7; 23 per 1000 person-years), which is significantly higher than in an age- and gender-matched background population. In conclusion, we found that aripiprazole overdoses had few and mild symptoms predominantly related to the sedative properties. We detected a benign cardiovascular safety profile and no new safety concerns. Our findings may support an increased threshold of 300 mg for hospital admission after a single-drug exposure with aripiprazole and symptoms not worse than light sedation.

Low-dose intravenous lipid emulsion for the treatment of severe quetiapine and citalopram poisoning

The treatment of quetiapine and/or citalopram poisoning is mainly supportive and involves gastric lavage, activated charcoal, intubation, and mechanical ventilation. Recently, however, there were reports of successful treatment with intravenous lipid emulsion. Here we report a case of a 19-year-old Caucasian girl who ingested approximately 6000 mg of quetiapine, 400 mg of citalopram, and 45 mg of bromazepam in a suicide attempt. The patient developed ventricular tachycardia and epileptic seizures 12 h after admission to the hospital. As the patient's condition deteriorated, we combined standard therapy (intubation, mechanical ventilation, and vasopressors) with low-dose intravenous lipid emulsion (ILE) (a total of 300 mL of 20 % lipid emulsion) and normalised her heart rhythm and stopped the seizures. She was discharged to the psychiatric ward after 48 h and home after a prolonged (2-month) psychiatric rehabilitation. Intravenous lipid emulsion turned out to be effective even in the lower dose range than previously reported for quetiapine poisoning in patients presenting with seizure and ventricular arrhythmia. To our knowledge, there are no case reports describing the use of ILE in treating citalopram poisoning.

Convulsive syncope related to a small dose of quetiapine in an adolescent with bipolar disorder

Quetiapine, an atypical antipsychotic, has been extensively used in patients with bipolar disorder. Overdose of quetiapine can result in severe complications, such as coma, seizure, respiratory depression, arrhythmia, and even death. However, the paucity of toxicological evaluation in adolescence causes more potential risks in this population. Herein, we present a case of hypotension and convulsive syncope after exposure to a small dose of quetiapine in a 16-year-old who was diagnosed with bipolar disorder. After cessation of quetiapine, no additional convulsive movements were reported. This case indicates that even in young patients without predisposing factors, close monitoring of adverse effects should be warranted for safety concerns, especially at the initiation of quetiapine treatment.

Misuse and Associated Harms of Quetiapine and Other Atypical Antipsychotics

Recent years have seen a significant increase in the reports of atypical antipsychotic diversion, misuse and even dependency syndrome. These reports have arisen amidst a marked increase in prescribing of these agents. Much of this increase in prescribing is because of a preferential use of these medications over typical antipsychotic agents to treat schizophrenia and bipolar disorder due to perceptions of fewer extrapyramidal side effects. However, there has also been a significant increase in the off-label prescribing of these medicines to treat less well evidence-based conditions. Misuse and abuse are perhaps surprising given the putative central role of dopamine in addiction and that these agents are dopamine antagonists. However, there may be other factors such as other pharmacological effects and increasing availability driving this misuse. It is also apparent that certain patient groups appear to be more at risk. Here, we explore the evidence behind the misuse of atypical antipsychotics with a focus of quetiapine. We consider the factors that may be driving this misuse, and then, we also detail some of the adverse effects that may ensue. We end by suggesting interventions at a prescriber and systems level that may be implemented to reduce the risk of atypical antipsychotic misuse.

Intentional Recreational Abuse of Quetiapine Compared to Other Second-generation Antipsychotics

INTRODUCTION

Case reports and poison center data have demonstrated that the second-generation antipsychotic quetiapine is being obtained and used for recreational abuse. The purpose of this study was to describe the relative rates of single-substance abuse for different atypical antipsychotics and compare their demographic and clinical features.

METHODS

We conducted a 10-year retrospective analysis of the National Poison Data System (NPDS) database (2003 - 2013). Trained nurses and pharmacists with specialty training in toxicology prospectively collect all NPDS data at poison control centers around the United States. We queried the NPDS for all cases of single-substance second-generation antipsychotic exposures coded as "intentional abuse." The data provided by the NPDS regarding rates and clinical features of quetiapine abuse and the abuse of all other second-generation antipsychotics were compared and described descriptively.

RESULTS

During the study period, 2,118 cases of quetiapine abuse and 1,379 cases of other second-generation antipsychotic abuse were identified. Quetiapine abuse was more common than the abuse of other second-generation antipsychotics, compromising 60.6% of all abuse cases during the study period. After quetiapine, the next most frequently abused medications were risperidone (530 cases, 15.2%) and olanzapine (246 cases, 7.0%). For all second-generation antipsychotics including quetiapine, central nervous system clinical effects were most common, including drowsiness, confusion, and agitation. Other serious clinical effects observed with second-generation antipsychotic abuse included hypotension, respiratory depression, and seizures.

CONCLUSION

Quetiapine abuse is relatively common, and is abused far more often than any other second-generation antipsychotic. Emergency physicians should be aware of the clinical effects that may occur after second-generation antipsychotic abuse.

Acute Respiratory Failure with a Single Dose of Quetiapine Fumarate

Objective:

To report a case of acute respiratory failure after a single dose of quetiapine fumarate in an elderly patient with a history of chronic obstructive pulmonary disease (COPD).

Case Summary:

A 92-year-old woman with a history of COPD was admitted to the hospital with pneumonia. Her symptoms improved with antibiotics. Because of acute agitation and delirium, quetiapine 50 mg twice daily was started. After receiving the first dose, the woman developed acute respiratory failure and severe central nervous system depression. She required mechanical ventilation and supportive care in the intensive care unit (ICU). She had a full recovery within 24 hours.

Discussion:

Quetiapine is an atypical antipsychotic that has been used successfully for the treatment of schizophrenia and bipolar disorder for many years. Recently, it has also been used to treat delirium and agitation. It has proven to be very safe, even in the elderly. In previously reported cases, serious adverse effects were seen in patients who ingested very high doses of quetiapine. Those patients required intubation and supportive care in the ICU. To our knowledge, as of January 19, 2006, this is the first case report of acute respiratory failure of such severity with one dose of quetiapine. Using the Naranjo probability scale, we conclude that the acute respiratory failure observed in this patient was probably related to quetiapine.

Conclusions:

This case suggests that quetiapine can have significant adverse effects even with a single 50 mg dose. Elderly patients, especially those with significant underlying pulmonary pathology, should be monitored closely when started on this medication.

Comparison of pediatric atypical antipsychotic exposures reported to U.S. poison centers

CONTEXT

The rise in atypical antipsychotic prescribing increases the risk of pediatric exposures. Published studies in children are limited.

OBJECTIVE

The objectives are to evaluate national poison center data on atypical antipsychotic exposures in young children and compare toxicity amongst selected agents.

MATERIALS AND METHODS

A retrospective study of U.S. National Poison Data System single substance exposures, from 2005 to 2013, of five atypical antipsychotics in children <6 years old, followed to known outcome was performed. Data were evaluated for reason, clinical effects, management site and outcome.

RESULTS

There were 16,935 exposures included: 5018 aripiprazole, 1735 olanzapine, 3904 quetiapine, 4778 risperidone and 1500 ziprasidone. Median age was two years. Most common reason was unintentional-general (90.6%). Therapeutic error occurred more often with risperidone (19.9%). Clinical effects occurred in 59.4% of aripiprazole, 57.9% of olanzapine, 56.6% of ziprasidone, 40.1% of risperidone, and 29.3% of quetiapine. The most frequent were drowsiness/lethargy (35.6%), tachycardia (6.9%), agitation (4.0%), and ataxia (3.3%). Drowsiness/lethargy occurred most with aripiprazole (47.6%), ziprasidone (46.5%) and olanzapine (45.1%) and least with quetiapine (20.5%) and risperidone (28.6%). Tachycardia and agitation both occurred most often with olanzapine (11.4% and 12.7%, respectively). Management sites were non-health care facility (28.0%), treated/discharged from emergency department (48.9%), admitted - noncritical care (11.4%), critical care (9.5%), and other/unknown (2.2%). Admission was lowest for risperidone (13.9%) and quetiapine (11.9%) and highest for olanzapine (32.9%). Coded outcomes were no effect (53.3%), minor (33.7%), moderate (12.1%), major (0.9%) and no deaths. Moderate/major outcomes occurred most often with ziprasidone (20.5%) and olanzapine (19.0%) and least often with quetiapine (5.3%) and risperidone (10.9%).

DISCUSSION AND CONCLUSION

Overall outcomes were favorable, with major toxicity in <1% of exposures. Risperidone and quetiapine exposures resulted in less toxicity. This finding may be attributed to higher frequency of therapeutic errors for risperidone but the reason for less toxicity with quetiapine is unclear.

Antipsychotic-related fatal poisoning, England and Wales, 1993-2013: impact of the withdrawal of thioridazine

CONTEXT

Use of second generation antipsychotics in England and Wales has increased in recent years whilst prescription of first generation antipsychotics has decreased.

METHODS

To evaluate the impact of this change and of the withdrawal of thioridazine in 2000 on antipsychotic-related fatal poisoning, we reviewed all such deaths in England and Wales 1993-2013 recorded on the Office for National Statistics drug poisoning deaths database. We also reviewed antipsychotic prescribing in the community, England and Wales, 2001-2013. Use of routine mortality data: When an antipsychotic was recorded with other drug(s), the death certificate does not normally say if the antipsychotic caused the death rather than the other substance(s). A second consideration concerns intent. A record of "undetermined intent" is likely to have been intentional self-poisoning, the evidence being insufficient to be certain that the individual intended to kill. A record of drug abuse/dependence, on the other hand, is likely to have been associated with an unintentional death. Accuracy of the diagnosis of poisoning: When investigating a death in someone prescribed antipsychotics, toxicological analysis of biological samples collected post-mortem is usually performed. However, prolonged attempts at resuscitation, or diffusion from tissues into blood as autolysis proceeds, may serve to alter the composition of blood sampled after death from that circulating at death. With chlorpromazine and with olanzapine a further factor is that these compounds are notoriously unstable in post-mortem blood. Deaths from antipsychotics: There were 1544 antipsychotic-related poisoning deaths. Deaths in males (N = 948) were almost twice those in females. For most antipsychotics, the proportion of deaths in which a specific antipsychotic featured either alone, or only with alcohol was 30-40%, but for clozapine (193 deaths) such mentions totalled 66%. For clozapine, the proportion of deaths attributed to either intentional self-harm, or undetermined intent was 44%, but for all other drugs except haloperidol (20 deaths) the proportion was 56% or more. The annual number of antipsychotic-related deaths increased from some 55 per year (1.0 per million population) between 1993 and 1998 to 74 (1.5 per million population) in 2000, and then after falling slightly in 2002 increased steadily to reach 109 (1.9 per million population) in 2013. Intent: The annual number of intentional and unascertained intent poisoning deaths remained relatively constant throughout the study period (1993: 35 deaths, 2013: 38 deaths) hence the increase in antipsychotic-related deaths since 2002 was almost entirely in unintentional poisoning involving second generation antipsychotics. Clozapine, olanzapine, and quetiapine were the second generation antipsychotics mentioned most frequently in unintentional poisonings (99, 136, and 99 deaths, respectively). Mentions of diamorphine/morphine and methadone (67 and 99 deaths, respectively) together with an antipsychotic were mainly (84 and 90%, respectively) in either unintentional or drug abuse-related deaths. Deaths and community prescriptions: Deaths involving antipsychotics (10 or more deaths) were in the range 11.3-17.1 deaths per million community prescriptions in England and Wales, 2001-2013. Almost all (96%) such deaths now involve second generation antipsychotics. This is keeping with the increase in annual numbers of prescriptions of these drugs overall (<1 million in 2000, 7 million in 2013), largely driven by increases in prescriptions for olanzapine and quetiapine. In contrast, deaths involving thioridazine declined markedly (from 40 in 2000 to 10 in 2003-2013) in line with the fall in prescriptions for thioridazine from 2001.

CONCLUSIONS

The removal of thioridazine has had no apparent effect on the incidence of antipsychotic-related fatal poisoning in England and Wales. That such deaths have increased steadily since 2001 is in large part attributable to an increase in unintentional deaths related to (i) clozapine, and (ii) co-exposure to opioids, principally diamorphine and methadone.

Coma After Quetiapine Fumarate Intentional Overdose in a 71-year-old Man: A Case Report

A 71-year-old man developed coma with severe respiratory failure, hypotension, and tachycardia induced by the intentional ingestion of quetiapine fumarate extended release (XR) 20 g. At the time, he had been treated for bipolar depression with venlafaxine 75 mg/day, lamotrigine 100 mg/day, pregabalin 75 mg/day, and quetiapine XR 400 mg/day for approximately 1 year. Comorbidities were hypertension treated with metoprolol, diabetes mellitus type 2 treated with metformin, and benign prostatic hyperplasia treated with silodosin. In the emergency room, about 4 h after ingestion of quetiapine fumarate XR, the presenting symptomatology was characterized by coma (Glasgow Coma Scale score 3), hypotension (blood pressure [BP] 90/60 mmHg), tachycardia (electrocardiogram [ECG] showed sinus tachycardia with heart rate 120 beats per minute and a QTc of 499 ms). A gastric lavage was performed and activated charcoal 50 g and magnesium sulfate 30 g was administered. About 6 h after ingestion, he developed marked desaturation and underwent mechanical ventilation; 13 h after ingestion, a severe hypotensive episode followed (BP 70/40), which was treated with an infusion of ringer lactate 500 cc. On the 3rd day after intentional overdose, an episode of agitation occurred; 4 days after ingestion, the quetiapine plasma level was found to be 42 ng/ml (within therapeutic range). At 5 days after ingestion, the patient developed septicemia caused by staphylococci (probably originating from the central vein catheter), which was treated with antibiotic therapy. On days 10 and 18 after the suicide attempt, two episodes of paroxysmal supraventricular tachycardia (PSVT) occurred and were successfully treated with intravenous adenosine triphosphate. The patient recovered completely without residual symptoms. In line with literature data, in this case report, symptoms of quetiapine overdose were tachycardia, agitation, hypotension, QT interval prolongation, and coma. A causal relationship between PSVT and quetiapine intoxication seems quite unlikely due to the drug level.

Ventricular dysrhythmias associated with poisoning and drug overdose: a 10-year review of statewide poison control center data from California

BACKGROUND

Ventricular dysrhythmias are a serious consequence associated with drug overdose and chemical poisoning. The risk factors for the type of ventricular dysrhythmia and the outcomes by drug class are not well documented.

OBJECTIVE

The aim of this study was to determine the most common drugs and chemicals associated with ventricular dysrhythmias and their outcomes.

METHODS

We reviewed all human exposures reported to a statewide poison control system between 2002 and 2011 that had a documented ventricular dysrhythmia. Cases were differentiated into two groups by type of arrhythmia: (1) ventricular fibrillation and/or tachycardia (VT/VF); and (2) torsade de pointes (TdP).

RESULTS

Among the 300 potential cases identified, 148 cases met the inclusion criteria. Of these, 132 cases (89%) experienced an episode of VT or VF, while the remaining 16 cases (11%) had an episode of TdP. The most commonly involved therapeutic classes of drugs associated with VT/VF were antidepressants (33/132, 25%), stimulants (33/132, 25%), and diphenhydramine (16/132, 12.1%). Those associated with TdP were antidepressants (4/16, 25%), methadone (4/16, 25%), and antiarrhythmics (3/16, 18.75%). Drug exposures with the greatest risk of death in association with VT/VF were antidepressant exposure [odds ratio (OR) 1.71; 95% confidence interval (CI) 0.705-4.181] and antiarrhythmic exposure (OR 1.75; 95% CI 0.304-10.05), but neither association was statistically significant. Drug exposures with a statistically significant risk for TdP included methadone and antiarrhythmic drugs.

CONCLUSIONS

Antidepressants and stimulants were the most common drugs associated with ventricular dysrhythmias. Patients with suspected poisonings by medications with a high risk of ventricular dysrhythmia warrant prompt ECG monitoring.

QTc interval prolongation and torsade de pointes associated with second-generation antipsychotics and antidepressants: a comprehensive review

We comprehensively reviewed published literature to determine whether it supported the link between corrected QT (QTc) interval prolongation and torsade de pointes (TdP) for the 11 second-generation antipsychotics and seven second-generation antidepressants commonly implicated in these complications. Using PubMed and EMBASE, we identified four thorough QT studies (one each for iloperidone, ziprasidone, citalopram, and escitalopram), 40 studies specifically designed to assess QTc interval prolongation or TdP, 58 publications based on data from efficacy and safety trials, 18 toxicology studies, and 102 case reports. Thorough QT studies, QTc prolongation-specific studies, and studies based on efficacy and safety trials did not link drug-associated QTc interval prolongation with TdP. They only showed that the drugs reviewed caused varying degrees of QTc interval prolongation, and even that information was not clear and consistent enough to stratify individual drugs for this risk. The few toxicology studies provided valuable information but their findings are pertinent only to situations of drug overdose. Case reports were most informative about the drug-QTc interval prolongation-TdP link. At least one additional well established risk factor for QTc prolongation was present in 92.2 % of case reports. Of the 28 cases of TdP, six (21.4 %) experienced it with QTc interval <500 ms; 75 % of TdP cases occurred at therapeutic doses. There is little evidence that drug-associated QTc interval prolongation by itself is sufficient to predict TdP. Future research needs to improve its precision and broaden its scope to better understand the factors that facilitate or attenuate progression of drug-associated QTc interval prolongation to TdP.

Intralipid therapy does not improve level of consciousness in overdoses with sedating drugs: a case series

OBJECTIVE

To assess the effect of intralipid emulsion therapy (ILE) in sedating drugs presenting to an urban emergency department.

METHODS

Following the introduction of a clinical protocol for the use of ILE a retrospective chart review was undertaken, which describes the use of ILE in treating sedating drug overdose in a facility with a tertiary referral level clinical toxicology unit. Demographic data as well as details of drug ingested, physiological parameters and disposition were extracted from the medical record.

RESULTS

Over a 7 month period nine cases were treated with intralipid, of which two were male and the median age was 33 years (17-52 years). Endotracheal intubation was required in seven cases and of the other two, one required a nasopharyngeal airway for several hours while being observed in a critical care area. One patient was managed in the intensive care unit without intubation. The median duration of ventilation in the seven patients was 31 h (22-82 h), and median length of stay for all nine cases was 63 h (24-133 h).

CONCLUSION

This study does not support any clinically significant effect of intralipid in sedating drug overdose.

Drug induced QT prolongation: the measurement and assessment of the QT interval in clinical practice

There has been an increasing focus on drug induced QT prolongation including research on drug development and QT prolongation, following the removal of drugs due to torsades de pointes (TdP). Although this has improved our understanding of drug-induced QT prolongation there has been much less research aimed at helping clinicians assess risk in individual patients with drug induced QT prolongation. This review will focus on assessment of drug-induced QT prolongation in clinical practice using a simple risk assessment approach. Accurate measurement of the QT interval is best done manually, and not using the measurement of standard ECG machines. Correction for heart rate (HR) using correction formulae such as Bazett's is often inaccurate. These formulae underestimate and overestimate the duration of cardiac repolarization at low and high heart rates, respectively. Numerous cut-offs have been suggested as an indicator of an abnormal QT, but are problematic in clinical practice. An alternative approach is the QT nomogram which is a plot of QT vs. HR. The nomogram has an 'at risk' line and QT-HR pairs above this line have been shown in a systematic study to be associated with TdP and the line is more sensitive and specific than Bazett's QTc of 440 ms or 500 ms. Plotting the QT-HR pair for patients on drugs suspected or known to cause QT prolongation allows assessment of the QT interval based on normal population QT variability. This risk assessment then allows the safer commencement of drugs therapeutically or management of drug induced effects in overdose.

Active metabolites as antidepressant drugs: the role of norquetiapine in the mechanism of action of quetiapine in the treatment of mood disorders

Active metabolites of some antipsychotic drugs exhibit pharmacodynamic and pharmacokinetic properties that may be similar to or differ from the original compound and that can be translated by a different profile of responses and interactions to clinical level. Some of these antipsychotics' active metabolites might participate in mechanisms of antidepressant activity, as m-chlorophenylpiperazine (aripiprazole), 9-OH-risperidone and norquetiapine. Norquetiapine exhibits distinct pharmacological activity from quetiapine and plays a fundamental role in its antidepressant efficacy. In this review, we analyze the differential pharmacological aspects between quetiapine and norquetiapine, both from the pharmacokinetic and pharmacodynamic perspectives (affinity for dopaminergic, noradrenegic, and/or serotonergic receptors, etc.), as well as differential neuroprotective role. The pharmacological differences between the two drugs could explain the differential clinical effect, as well as some differences in tolerability profile and drug interactions. The available data are sufficient to arrive at the conclusion that antidepressant activity of quetiapine is mediated, at least in part, by the active metabolite norquetiapine, which selectively inhibits noradrenaline reuptake, is a partial 5-HT1A receptor agonist, and acts as an antagonist at presynaptic α2, 5-HT2C, and 5-HT7 receptors.

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.

Probable quetiapine-mediated prolongation of the QT interval

PURPOSE

QT prolongation can occur with both first- (FGA) and second-generation antipsychotics (SGA). QT prolongation was identified in an adult patient who presented to the emergency room with schizophrenia, fluid and electrolyte imbalances, and pneumonia. Quetiapine, an SGA, was a component of the pharmacotherapy regimen. Based on the Naranjo adverse drug reaction probability scale rating criteria, a probable causal association was made.

METHODS

PubMed and Ovid were searched using the terms antipsychotic, psychotropic, QT interval, corrected QT interval (QTc) prolongation, and quetiapine. References were examined for additional articles related to antipsychotic drugs and the QT interval.

DISCUSSION

In this patient, the use of quetiapine was identified as a contributing factor in QT prolongation. Prior QT prolongation was experienced with ziprasidone, another SGA. The antidepressant and dose remained consistent throughout the inpatient course of treatment. Other risk factors in this patient included hypokalemia, dehydration, pneumonia, age, gender, and concurrent usage of an antidepressant. Dual psychiatric diagnoses, preexisting cardiovascular disease, and electrolyte disturbances may increase this risk potential.

CONCLUSION

Psychiatric patients may be more at risk of cardiovascular complications, such as QT interval prolongation. The pharmacist can help evaluate risk factors and provide input into the care of all patients, particularly those identified as at risk.

Evaluation of a QT nomogram for risk assessment after antidepressant overdose

AIMS

A QT-heart rate nomogram has recently been proposed as a means of identifying patients at risk of torsades de pointes after antidepressant overdose, based on published cases of drug-induced torsades de pointes. The present study sought to examine the performance of the nomogram in patients who ingest an antidepressant overdose but do not develop arrhythmia.

METHODS

A retrospective case control study of patients presenting to hospital after overdose of citalopram, mirtazapine and venlafaxine was carried out. The primary outcome variable was QT higher than the nomogram, and was compared with occurrence of QT(c) (QT corrected by Bazett's formula) greater than ≥440 ms and QT(c) ≥500 ms, with comparison between drugs. Data are expressed as proportions in each group with 95% confidence intervals.

RESULTS

There were 858 electrocardiograms from 541 patients. QT was higher than the nomogram in 2.4% (1.4, 4.1%), whereas QT(c) was ≥440 ms in 23.1% (95% CI 19.8, 26.8%), and QT(c) was ≥500 ms in 1.1% (0.5, 2.5%). Citalopram overdose was more likely to be associated with QT higher than the nomogram compared with the other agents (difference 7.0%, 95% CI 2.9, 11.9%, P = 0.001) and more likely to be associated with QT(c) ≥440 ms (difference = 11.0%, 95% CI 2.6, 19.0%, P = 0.013).

CONCLUSIONS

The QT nomogram was associated with a lower false positive rate than widely accepted QT(c) criteria, and allowed detection of different effects of individual drugs. The nomogram offers potential advantages over QT(c) criteria and merits further investigation in a clinical setting.

A comparison of venlafaxine and SSRIs in deliberate self-poisoning

To compare the clinical features of deliberate self-poisoning with venlafaxine and selective serotonin reuptake inhibitors (SSRIs) presenting to the emergency department of an Australian tertiary referral hospital. A retrospective cohort study comparing all 36 patients who presented with venlafaxine self-poisoning with 44 randomly selected patients with SSRI self-poisoning between 1997 and 2006. Patients who had overdosed on venlafaxine were older (mean age 37.4 versus 28.8 years, p ≤ 0.001) and generally exhibited a higher degree of suicidal intent (p ≤ 0.017). Median venlafaxine dose taken was 35 defined daily doses (DDDs) compared with SSRIs 19.4 DDDs. Those who ingested venlafaxine were more likely to become confused (25% versus 0%; p = 0) and have mydriasis (19.4% versus 2%; p ≤ 0.02), than those who took SSRIs. One patient from the venlafaxine group died. Compared with SSRI self-poisoners, patients who deliberately ingested venlafaxine were more likely to exhibit serious suicide intent. They were also more likely to be older, take a higher DDD of the drug, and have confusion and mydriasis. This has implications for management of severely depressed and suicidal patients.

Prolonged delirium after quetiapine overdose

Quetiapine is an atypical antipsychotic agent increasingly used to treat schizophrenia and bipolar disorder in pediatric patients. Few published data exist concerning quetiapine's effects in therapeutic settings or short-term overdose in pediatric and adolescent populations. In this report, we describe a 15-year-old adolescent girl who experienced continued delirium 5 days after an overdose of quetiapine, trazodone, and clonidine. The patient initially presented with sedation and stable vital signs. After 3 days of gradual improvement, she experienced episodes of delirium coinciding with an increase in resting heart rate. On the basis of suspicion for quetiapine-associated antimuscarinic effects, the patient was administered intravenously with physostigmine on the fifth day after ingestion. Treatment resulted in a brief resolution of symptoms. Serum quetiapine levels measured 1 day and 5 days after ingestion were 3400 and 4800 ng/mL, respectively. The use of physostigmine and interpretation of serum levels are discussed further.

Unexpected interaction between quetiapine and valproate in patients with bipolar disorder

Quetiapine, a second-generation antipsychotic originally used in the treatment of schizophrenia, was also found to be effective as monotherapy or as an adjunctive therapy for acute mania. Delirium in patients treated with quetiapine seems to be a rare phenomenon; however, we report two patients with bipolar disorder who developed delirium when prescribed quetiapine as an adjunct to valproate for acute mania. Both had previously developed mild renal insufficiency after an episode of lithium intoxication. The delirium resolved after quetiapine was discontinued. Unexpected interactions may occur when medications are combined without being subject to controlled clinical trials.

Intoxication after extreme oral overdose of quetiapine to attempt suicide: pharmacological concerns of side effects

Quetiapine is an atypical antipsychotic approved for the treatment of patients with psychotic disorders. Since approvement several case reports about intoxication with quetiapine were linked mainly with tachycardia, QT_c-prolongation, somnolence, and hyperglycemia. Here, we present the first case report of an intoxication with an extreme overdose of quetiapine (36 g), ingested by a 32-year-old female (62 kg bodyweight) to attempt suicide. Symptoms associated with intoxication were coma without arterial hypotension, persistent tachycardia, hyperglycemia, and transient hypothyreoidism. QT_c-interval was moderately extended. Management consisted of intubation for airway protection, gastric lavage, the use of activated charcoal, i.v. saline, and observation for 17 hours on an intensive care unit. Despite the extremely high dose of quetiapine, the patient recovered completely without residual symptoms.