Delayed recovery associated with persistent serum concentrations after clozapine overdose

Evaluation of various scoring systems as predictors of the need for intensive care unit admission and other adverse outcomes among patients with acute clozapine poisoning

Acute clozapine poisoning (ACP) is frequently reported worldwide. We evaluated the efficacy of the Poison Severity Score (PSS), Acute Physiology and Chronic Health Evaluation II (APACHE II) score, Rapid Emergency Medicine Score (REMS), and Modified Early Warning Score (MEWS) as predictors for intensive care unit (ICU) admission, mechanical ventilation (MV), mortality, and length of hospital stay in patients with ACP. A retrospective cohort study was conducted using records of patients diagnosed with ACP from January 2017 to June 2022 and admitted to an Egyptian poison control center. Analyzing 156 records showed that all assessed scores were significant predictors of the studied outcomes. The PSS and APACHE II score showed the highest area under the curve (AUC) as ICU admission predictors with insignificant variations. The APACHE II score showed the best discriminatory power in predicting MV and mortality. Nevertheless, MEWS exhibited the highest odds ratio (OR) as an ICU predictor (OR = 2.39, and 95% confidence interval = 1.86-3.27) and as a mortality predictor (OR = 1.98, and 95% confidence interval = 1.16-4.41). REMS and MEWS were better predictors of length of hospital stay compared with the APACHE II score. The simpler, lab-independent nature and the comparable discrimination but higher odds ratio of MEWS compared with APACHE II score justify MEWS' superior utility as an outcome predictor in ACP. We recommend using either the APACHE II score or MEWS, depending on the availability of laboratory investigations, resources, and the case's urgency. Otherwise, the MEWS is a substantially feasible, economical, and bedside alternative outcome predictor in ACP.

Clozapine Intoxication in a Patient on Chronic Use With a Short-Term Noncompliance

Clozapine has been associated with various adverse effects at both subtherapeutic and standard doses. These adverse effects are most commonly seen during the initiation of therapy in treatment-naïve patients. However, reports of intoxication in patients with long-term use of clozapine are yet to be documented. We highlight the case of a 42-year-old gentleman who had been on long-term clozapine use and presented with an altered mental status after being resumed on full standard doses without careful titration of clozapine after a short period of medication noncompliance. His workup in the hospital was largely unremarkable, and his presentation was attributed to the resumption of clozapine without medication titration. This is the first case to demonstrate the necessity of careful titration regardless of previous treatment history and highlights that patients should be started on clozapine at low levels to avoid the possibility of acute intoxication.

A case report of acute hypothermia during initial inpatient clozapine titration with review of current literature on clozapine-induced temperature dysregulations

BACKGROUND

Here we describe a unique case of clozapine-associated hypothermia during initial titration of this medication in an acute inpatient psychiatry setting. Only a handful of cases on this topic have been published. We discuss possible pharmacologic mechanisms supporting or refuting the propensity of clozapine to induce hypothermia, as well as risk factors for clozapine-induced hypothermia, and a comparison to clozapine-induced hyperthermia.

CASE PRESENTATION

A 70 year-old African American female with treatment-refractory schizoaffective disorder developed hypothermia with a nadir temperature of 89 °F (31.7 °C) after 7 days on clozapine, on a total dose of 50 mg twice daily. Accompanying symptoms included bradycardia, hypotension, QTc prolongation, tachypnea, hypoxemia, and an absence of shivering. The patient was transferred to the ICU, and rewarmed within 10 h with the discontinuation of her clozapine, ziprasidone, and carvedilol. Broad spectrum antibiotics were initiated, but discontinued shortly after, as the patient had no leukocytosis, and blood cultures were negative.

DISCUSSION

While hypoglycemia, hypothyroidism, sepsis, and stroke were effectively ruled out, alternative drug-disease (including chronic kidney disease), and drug-drug interactions were considered possible contributing features. Benzodiazepines, valproic acid, ziprasidone, and the numerous antihypertensive agents the patient was taking were considered as either primary or compounding factors for hypothermia. After exclusion or inclusion of these alternative causes, we calculated a score of 4 (possible) for clozapine-induced hypothermia on the Naranjo Scale.

CONCLUSIONS

Clozapine-induced hypothermia may occur more commonly than clinicians believe. Practitioners should be cognizant of this potentially fatal phenomenon, and monitor for temperature dysregulations while on clozapine, especially during initial titration, in those with multiple comorbid factors, and on additional medications that may contribute to hypothermia.

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.

Clozapine Intoxication Mimicking Acute Stroke

Clozapine is an atypical antipsychotic drug prescribed for treatment-resistant schizophrenia. The risk of adverse hematologic, cardiovascular, and neurologic effects has tempered its use, and reports of overdoses remain rare. We report a case of accidental acute clozapine intoxication in a clozapine-naïve patient, who presented with symptoms mimicking acute stroke and later developed status epilepticus. Clozapine intoxication is a rare presentation in the emergency department with potential for iatrogenic harm if not correctly identified.

Clozapine-Induced Cardiovascular Side Effects and Autonomic Dysfunction: A Systematic Review

Background: Clozapine is the antipsychotic of choice for treatment-resistant schizophrenia and has minimal risk for extrapyramidal symptoms. Therapeutic benefits, however, are accompanied by a myriad of cardiometabolic side-effects. The specific reasons for clozapine's high propensity to cause adverse cardiometabolic events remain unknown, but it is believed that autonomic dysfunction may play a role in many of these.

Objective: This systematic review summarizes the literature on autonomic dysfunction and related cardiovascular side effects associated with clozapine treatment.

Method: A search of the EMBASE, MEDLINE, and EBM Cochrane databases was conducted using the search terms antipsychotic agents, antipsychotic drug^*, antipsychotic^*, schizophrenia, schizophren^*, psychos^*, psychotic^*, mental ill^*, mental disorder^*, neuroleptic^*, cardiovascular^*, cardiovascular diseases, clozapine^*, clozaril^*, autonomic^*, sympathetic^*, catecholamine^*, norepinephrine, noradrenaline, epinephrine, adrenaline.

Results: The search yielded 37 studies that were reviewed, of which only 16 studies have used interventions to manage cardiovascular side effects. Side effects reported in the studies include myocarditis, orthostatic hypotension and tachycardia. These were attributed to sympathetic hyperactivity, decreased vagal contribution, blockade of cholinergic and adrenergic receptors, reduced heart rate variability and elevated catecholamines with clozapine use. Autonomic neuropathy was identified by monitoring blood pressure and heart rate changes in response to stimuli and by spectral analysis of heart rate variability. Metoprolol, lorazepam, atenolol, propranolol, amlodipine, vasopressin and norepinephrine infusion were used to treat tachycardia and fluctuations in blood pressure, yet results were limited to case reports.

Conclusion: The results indicate there is a lack of clinical studies investigating autonomic dysfunction and a limited use of interventions to manage cardiovascular side effects associated with clozapine. As there is often no alternative treatment for refractory schizophrenia, the current review highlights the need for better designed studies, use of autonomic tests for prevention of cardiovascular disease and development of novel interventions for clozapine-induced side effects.

Teaching Application of Clinical Pharmacology Skills Using Unusual Observations from Clozapine Overdoses

Massive drug overdoses provide a unique opportunity to observe human pharmacokinetic data not otherwise ethically available. They can also provide practical examples for teaching thoughtful application of the principles of clinical pharmacology. Following a case of clozapine overdose in which onset of toxicity was delayed by 72 hours, a probable explanation was found in an exploration of three cases with unusual concentration-time profiles and revealed unexpected implications for the management of clozapine overdoses. The authors systematically addressed the possible mechanisms proposed in the literature for an unusual plateau in concentrations observed in three clozapine overdoses. The effects that the most commonly suggested explanations (i.e., delayed absorption and saturated or impaired metabolism) would have on both clozapine and norclozapine concentrations were then modeled using the data available from those three cases to provide an objective illustration for comparison. This exercise was then used as a teaching seminar, leading students through the steps required to reach a logical explanation for the observed delayed toxicity and to consider the implications for therapy. Delayed absorption best predicted the sustained serum clozapine and norclozapine concentrations observed in three cases, and modeling suggests that much of the drug remains in the gut, available for absorption for days following an overdose. As a seminar, the exercise provides students with a practical example of the value of systematically ruling out possible explanations by considering what effects various pharmacokinetic alterations would have on observed data. Absorption following massive clozapine overdose appears fundamentally different from that with conventional dosing. This suggests a potential for delayed or prolonged toxicity, extending well beyond the time frame predicted by its half-life, unless aggressive and sustained efforts are applied to remove clozapine from the gut. Data from drug overdoses provide opportunities to explore unusual aspects of pharmacokinetics, better understand future overdoses of the same agent, and present excellent material for teaching. A seminar illustrating the role that thoughtful application of pharmacologic principles had in addressing this case is now used to introduce the clinical aspects of pharmacology to students at our institutions.

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.

Hemoperfusion in the treatment of acute clozapine intoxication in China

BACKGROUND AND AIMS

No systematic study has focused on the characteristics and outcome of acute clozapine intoxication, although clozapine is the most widely used antipsychotic agent in China. The study reported herein examined the features of clozapine intoxication and the therapeutic effect of hemoperfusion (HP).

METHODS

In a retrospective chart review, the notes of 47 patients who attempted suicide by ingesting large amounts of clozapine and were treated at the only psychiatric emergency service in Beijing were analyzed. Of the 20 unconscious patients with plasma clozapine concentrations of more than 2000 ng/mL, 14 received a combination of HP and symptomatic treatment, whereas the other 6 and the remaining 27 patients received only symptomatic treatment. Patients' psychiatric conditions and both plasma clozapine and norclozapine concentrations were closely monitored and registered.

RESULTS

One patient died of pulmonary edema and subsequent heart failure, but the rest of the patients recovered without any sequelae. Patients who received HP regained consciousness significantly faster than their counterparts with the same level of clozapine plasma concentration (>2000 ng/mL) who did not receive HP.

CONCLUSIONS

A combination of HP and symptomatic treatment is the best therapeutic option when plasma clozapine concentration is high.

Suspected clozapine poisoning in the UK/Eire, 1992–2003

OBJECTIVE

Toxicological analyses are often performed to investigate suspected poisoning, but the interpretation of results may not be straightforward. We studied suspected poisoning cases 1992-2003 where blood clozapine and N-desmethylclozapine (norclozapine) were measured in order to assess the relationship of these parameters to outcome.

METHODS

Samples were referred from clinicians, pathologists/coroners, or via the Clozaril Patient Monitoring Service (CPMS, Novartis). Information was gathered from clinical, post-mortem, or coroners' reports.

RESULTS

There were seven fatal [five male, two female; median (range) age 28 (24-41) year] and five non-fatal [four male, one female; median age 35 (26-41) year] clozapine overdoses. The median post-mortem blood clozapine and norclozapine concentrations were 8.2 (3.7-12) and 1.9 (1.4-2.4)mg/L, respectively [median clozapine:norclozapine ratio 4.4 (2.9-5.1)]. The median plasma clozapine and norclozapine concentrations (first or only sample) were 3.9 (1.7-7.0) and 0.40 (0.30-0.70)mg/L, respectively [median clozapine:norclozapine ratio 7.6 (5.3-18)] in the remainder. These overdoses were in patients who were poorly or non-adherent to clozapine, or who had taken tablets prescribed for someone else. In 54 further people who died whilst receiving clozapine [38 male, 16 female; median age 41 (22-70) year], the median post-mortem blood clozapine and norclozapine concentrations were 1.9 (0-7.7, n = 43) and 1.4 (0-6.0, n = 39)mg/L, respectively [median clozapine:norclozapine ratio 1.5 (0.4-7.6, n = 38)]. The median post-mortem increase in blood clozapine and norclozapine as compared to the most recent ante-mortem measurement was 489 (98-5,350)% and 371 (139-831)%, respectively [median sample time before death 14 (0-30, n = 21) days].

CONCLUSION

Clozapine poisoning cannot be diagnosed on the basis of blood clozapine and norclozapine concentrations alone. The analysis of ante-mortem blood specimens collected originally for white cell count monitoring and the blood clozapine:norclozapine ratio may provide additional interpretative information.

Safety and tolerability of emerging pharmacological treatments for bipolar disorder

OBJECTIVES

Over the past few years numerous new agents have been examined for their efficacy in bipolar disorder (BPD). New antiepileptic agents and atypical antipsychotics currently form the bulk of these emerging agents. As the armamentarium for treating BPD increases, it allows for the possibility of choosing drugs on the basis of their tolerability as well as their efficacy, rather than on efficacy alone.

METHODS

Efficacy data for newer antiepileptic drugs (lamotrigine, topiramate, gabapentin, oxcarbazepine) and atypical antipsychotics (olanzapine, clozapine, risperidone, quetiapine, ziprasidone, aripiprazole) are briefly reviewed. The article focuses on relative safety and tolerability of these agents.

RESULTS

In general, most of these newer agents have better side effect and tolerability profiles than older agents commonly used to treat BPD (lithium, valproate, carbamazepine); however, these must be weighed against efficacy demonstrated to date in randomized, controlled trials. Cognitive impairment is a concern with topiramate, weight gain and risk of diabetes with some of the atypical antipsychotic agents, and rash with lamotrigine.

CONCLUSIONS

Side effects of newer emerging agents for the treatment of BPD can be effectively managed and the risks reduced by instituting practical strategies early in management.