Quetiapine in Overdosage

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.

Prognostic factors in acute poisoning with central nervous system xenobiotics: development of a nomogram predicting risk of intensive care unit admission

Background

Acute intoxication with central nervous system (CNS) xenobiotics is an increasing global problem. Predicting the prognosis of acute toxic exposure among patients can significantly alter the morbidity and mortality. The present study outlined the early risk predictors among patients diagnosed with acute exposure to CNS xenobiotics and endorsed bedside nomograms for identifying patients requiring intensive care unit (ICU) admission and those at risk of poor prognosis or death.

Methods

This study is a 6-year retrospective cohort study conducted among patients presented with acute exposure to CNS xenobiotics.

Results

A total of 143 patients' records were included, where (36.4%) were admitted to the ICU, and a significant proportion of which was due to exposure to alcohols, sedative hypnotics, psychotropic, and antidepressants (P = 0.021). ICU admission was associated with significantly lower blood pressure, pH, and HCO₃ levels and higher random blood glucose (RBG), serum urea, and creatinine levels (P < 0.05). The study findings indicate that the decision of ICU admission could be determined using a nomogram combining the initial HCO₃ level, blood pH, modified PSS, and GCS. HCO₃ level < 17.1 mEq/L, pH < 7.2, moderate-to-severe PSS, and GCS < 11 significantly predicted ICU admission. Moreover, high PSS and low HCO₃ levels significantly predicted poor prognosis and mortality. Hyperglycemia was another significant predictor of mortality. Combining initial GCS, RBG level, and HCO₃ is substantially helpful in predicting the need for ICU admission in acute alcohol intoxication.

Conclusion

The proposed nomograms yielded significant straightforward and reliable prognostic outcomes predictors in acute exposure to CNS xenobiotics.

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.

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.

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.

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.

Should We Be Using the Poisoning Severity Score?

INTRODUCTION

Despite the existence of a number of severity-of-illness classifications for other areas of medicine, toxicology research lacks a well-accepted method for assessing the severity of poisoning. The Poisoning Severity Score (PSS) was developed in the 1990s in Europe as a scoring system for poisonings reported to a poison center in order to describe a patient's most severe symptomatology. We reviewed the literature to describe how the PSS is utilized and describe its limitations.

DISCUSSION

We searched the medical literature in all languages using PUBMED, EMBASE, and SCOPUS from inception through August 2013 using predefined search terms. Out of 204 eligible publications, 40 met our criteria for inclusion in this review. There has been a paucity of published studies from North America that used the PSS. In some cases,  the PSS was misapplied or modified from standard scoring, making a bottom line appraisal of the validity or reliability of the original version of the instrument challenging. The PSS has several subjective criteria, is time consuming to score, and is likely to be of little use with some types of poisonings, limiting its clinical utility.

CONCLUSION

The PSS was developed as a tool to document encounters with poisoned patients. However, it is used infrequently and, when applied, has been misused or modified from its original form. In its current form, it has limited clinical utility and likely cannot be broadly applied to many exposures due to their unique clinical circumstances. With better global collaboration among medical toxicologists, it is possible that a modified score could be developed for use clinically or as a research instrument.

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.

Plasma quetiapine in relation to prescribed dose and other factors: data from a therapeutic drug monitoring service, 2000-2011

OBJECTIVE

Suggested predose plasma quetiapine target ranges for effective therapy in schizophrenia lie between 50 and 500 µg/l. We aimed to examine data from a quetiapine therapeutic drug monitoring (TDM) service to assess the plasma quetiapine concentrations attained at specified doses in clinical practice.

METHOD

We studied TDM data from patients given immediate-release quetiapine in the period 2000-2011.

RESULTS

There were 946 samples from 487 patients (257 males, age at time of first sample, median [range] 34 [14-87] years, and 230 females, age at time of first sample, median [range] 38 [10-92] years). The plasma quetiapine concentration was <50 and <100 µg/l in 30% and 50% of samples, respectively (no quetiapine detected in 9% of samples). The relationship between dose and plasma quetiapine was poor. The mean (95% confidence interval [CI]) quetiapine dose was higher (t = 3.6, df = 446, p <0.01) in males versus females (641 [600-1240] and 548 [600-943] mg/day, respectively), although there was no difference in median dose (600 mg/day) or in the mean (95% CI) plasma quetiapine concentrations attained. Smoking habit had no discernible effect on plasma quetiapine concentration.

CONCLUSIONS

There was a poor relationship between dose and plasma quetiapine concentration in this study, as found by others. This is probably because of the short plasma half-life of the drug, at least in part. Nevertheless, quetiapine TDM can help assess adherence and measurement of quetiapine metabolites, notably N-desalkylquetiapine, as well as quetiapine itself may enhance the value of quetiapine TDM in future.

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.

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.

Survival from coma induced by an intentional 36-g overdose of extended-release quetiapine

Quetiapine is a second-generation antipsychotic drug approved for the treatment of bipolar disorders and schizophrenia. Acute quetiapine overdose is rare, and quetiapine has long been thought to be safer than other antipsychotics. Nevertheless, as reported in the literature, the severity of the effect of quetiapine overdose has not been associated with a high serum concentration of the drug or with the reported ingested dose. In this article, we report a case of survival from coma induced by a massive extended-release (XR) quetiapine ingestion at a dose greater than reported in some previous fatal cases. A 34-year-old woman with chronic schizophrenia ingested 36 g of quetiapine fumarate XR for attempted suicide. She was initially lethargic, but her clinical conditions rapidly deteriorated and she collapsed unconscious. The woman was taken to the nearest hospital, where the medical emergency team found her in deep coma with response only to deep painful stimuli (Glasgow Coma Scale 9). An endotracheal tube was inserted for airway protection, and the patient was transferred to a critical care area for ventilatory support and maintenance of hydration status and electrolytic balance. Spontaneous breathing was restored in approximately 36 hours, and a few days later, she was discharged without reporting clinical complications. This is the first case of coma induced by an intentional 36-g overdose of quetiapine XR. Given the widespread use of quetiapine and the lack of information about its toxicity in overdose, this case report reinforces the importance of closely monitoring patients taking quetiapine and helps to better define the safety of this drug.

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.

High-dose loading with extended release quetiapine

Extended release quetiapine fumarate (quetiapine XR) was initiated at the recommended maximum dose 800 mg and maintained at the same dose in five patients with schizophrenia. Although the loadings of quetiapine XR were well tolerated in four patients in these five cases, one patient with a history of cerebral infarction developed serious side-effects, notably bladder distention and dizziness. This case series indicates that loading with maximum dose quetiapine XR may be tolerable and used safely in most schizophrenia patients with no other concurrent disease such as brain infarction.

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.

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.

Rhabdomyolysis in MDMA intoxication: a rapid and underestimated killer. "Clean" Ecstasy, a safe party drug?

BACKGROUND

Ecstasy is a popular drug among young adults. It is often thought to be safe. The dose of methylenedioxymethamphetamine (MDMA) in a tablet of Ecstasy varies greatly, and there is also a difference in individual response to a dose of MDMA.

OBJECTIVES

To increase the awareness of potential mortality in MDMA use.

CASE REPORT

We report the case of a patient with a lethal intoxication after pure MDMA intoxication. The serum toxicology screening showed an elevated level of MDMA (1.5 mg/L) but no other amphetamines or other drugs.

CONCLUSIONS

The cause of death was a rapidly evolving hyperkalemia due to rhabdomyolysis. There is still a need to educate the public about the dangers of this so-called "safe" party drug.

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.

Quetiapine: Relatively safe in overdose?

Compared to other antipsychotics quetiapine has been reported to be relatively safer in overdose. We report a case with paranoid schizophrenia who attempted suicide with 1400 mg of quetiapine and manifested drowsiness, supraventricular tachycardia (167/minute) and minimal ST depression in leads V1 to V6 on ECG; all other physiological parameters were normal. Gastric lavage, lorazepam 2mg i/v to control agitation, and 14-hour observation in emergency ended in she being sent home. Subsequently she was successfully managed with ECTs, and quetiapine 600mg and risperidone 6mg daily. This report tends to support the literature suggesting quetiapine as a relatively-safer-in-overdose antipsychotic, and preferable in medication-overdose-suicidal-risk cases.

Pharmacokinetics and pharmacodynamics of quetiapine in a patient with a massive overdose

We present a case of massive overdose with the atypical antipsychotic quetiapine in a 34-year-old woman (body weight 65 kg). At admission, approximately 2 to 4 hours after ingestion of approximately 24 g of quetiapine, the patient was comatose (Glasgow Coma Scale score 5), requiring orotracheal intubation and transfer to the intensive care unit. Because of myoclonic jerks and generalized seizures, benzodiazepines were administered. In addition to transient mild hypotension after intubation, the main cardiovascular manifestation was sinus tachycardia. The QT interval was normal, and the QTc interval (Bazett's correction) was maximally prolonged to 620 ms. However, no malignant arrhythmias were observed. The patient recovered within 2 days but remained agitated and aggressive, for which she was transferred to the psychiatric clinic. The pharmacokinetics of quetiapine in such a large overdose could not be described by simple first-order kinetics. The initially observed rapid decline of the plasma concentrations of quetiapine could be simulated by first-order kinetics (half life = 4.1 hr) and can most probably be explained by rapid distribution into tissues. The final elimination of the drug from the body occurred after approximately 34 hours at much slower rate, most probably reflecting redistribution from tissues into blood and consecutive hepatic clearance of the drug.

Pharmacokinetics of Quetiapine in Overdose and the Effect of Activated Charcoal

The aim of the study was to investigate the pharmacokinetics of quetiapine overdose and the effect of charcoal. The data set included 204 concentration-time points from 54 quetiapine overdose events (median dose 2,700 mg (300-24,000 mg)). Charcoal was administered 0.5-6 h after 19 overdoses. A fully Bayesian methodology for population pharmacokinetic analysis was used and data were modelled using WinBUGS. Uncertainty in the dose history was considered in model building by estimating dose amount and dose time within a possible range. Inclusion of informative priors stabilized the model and population parameter values could be estimated well. A one-compartment model with first-order input and first-order elimination described the data. The final model included uncertainty in dose time. The median and interquartile range of the half-life for individual patients was 6.6 h (4.9-8.4 h). Charcoal was estimated to reduce fraction absorbed by 35%. Co-ingested CYP3A4 inhibitors appeared to decrease clearance and CYP3A4 inducers increase clearance. Charcoal administration may be beneficial after quetiapine overdose.

Quetiapine: efficacy, tolerability and safety in schizophrenia

Quetiapine, a dibenzothiazepine derivative, is an atypical antipsychotic, multireceptor antagonist that has a preclinical profile similar to clozapine. Randomized studies have demonstrated the efficacy of quetiapine relative to placebo in the treatment of acute relapse and the long-term management of schizophrenia. Quetiapine is generally well tolerated relative to other antipsychotic medications, although side effects include sedation, orthostatic hypotension, anticholinergic and metabolic side effects. The purpose of this article is to critically review the current literature on quetiapine with an emphasis on emergent themes and key findings in the use of this agent for the treatment of schizophrenia. There are also continued efforts to understand, predict and manage the side-effect risk with quetiapine.