Minimal Dose for Severe Poisoning and Influencing Factors in Acute Human Clozapine Intoxication: A 13-Year Retrospective Study

Abnormal blood concentration changes in a 71-year-old female who survived a 10,000mg overdose of clozapine: a case report

BACKGROUND

Clozapine is a highly effective second-generation antipsychotic with few extrapyramidal reactions, making it a preferred choice among clinicians. However, instances of acute clozapine poisoning resulting from suicide attempts and misuse have been reported. Through our review of existing literature, we identified that we believe to be the highest recorded overdose of clozapine in elderly patients, resulting in a nonfatal outcome.

CASE PRESENTATION

The case report involves a 71-year-old female with a history of depression who ingested a dose of 10,000 mg of clozapine. Approximately 6 h after the overdose, the clozapine level was 5,200 μg/L, significantly surpassing the recommended therapeutic concentration range of 350-600 μg/L. After gastric lavage and hemoperfusion, the blood level dropped to 1847.11 μg/L. Notably, during therapeutic drugs monitoring (TDM), we found a perplexing spike in the patient's blood level to 5554.15 μg/L after the second hemoperfusion.

CONCLUSION

In this case we mainly focused on the abnormal fluctuations in the concentration of clozapine. We conducted a comprehensive analysis of potential factors contributing to this abnormal phenomenon in terms of the patient's age, clinical symptoms, various laboratory test indexes, and the pharmacokinetics of clozapine. Our findings underscore the importance of timely TDM and the precision of results in managing elderly patients experiencing high-dose clozapine poisoning.

Clozapine-Induced Severe Toxicity: Exploring the Pharmacokinetic Profile of Clozapine and Its Significance in Hemodynamic Instability - A Case Report

Hemodynamic instability in patients with clozapine intoxication can indirectly reflect the serum concentration of clozapine.We have described a case of a 32-year-old pregnant woman who developed life-threatening clozapine toxicity at 28 weeks of gestation. The levels of clozapine and norclozapine in the serum were high. We initiated hemoperfusion(HP) and other detoxification therapies to remove the drug. The patient had severely dilated peripheral blood vessels, which led to cardiac symptoms such as fatal hypotension and uncontrollable tachycardia, resulting in very high cardiac output and elevated Central venous oxygen saturation (ScvO2). Pharmacological intervention significantly improved the hemodynamics.In light of our observations in the ongoing case, we posit that evaluating hemodynamic parameters before and after blood detoxification could serve as a valuable means to gauge effectiveness and provide guidance for treatment.

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.

The atypic antipsychotic clozapine inhibits multiple cardiac ion channels

Clozapine is an atypical neuroleptic used to manage treatment-resistant schizophrenia which is known to inhibit cardiac hERG/K_V11.1 potassium channels, a pharmacological property associated with increased risk of potentially fatal Torsades de Pointes (TdP) and sudden cardiac death (SCD). Yet, the long-standing clinical practice of clozapine does not show a consistent association with increased incidence of TdP, although SCD is considerably higher among schizophrenic patients than in the general population. Here, we have established the inhibitory profile of clozapine at the seven cardiac ion currents proposed by the ongoing comprehensive in vitro pro-arrhythmia (CiPA) initiative to better predict new drug cardio-safety risk. We found that clozapine inhibited all CiPA currents tested with the following rank order of potency: K_V11.1 > Na_V1.5 _{(late current)} ≈ Ca_V1.2 ≈ Na_V1.5 _{(peak current)} ≈ K_V7.1 > K_V4.3 > K_ir2.1 _{(outward current)}. Half-maximal inhibitory concentrations (IC₅₀) at the repolarizing K_V11.1 and K_V7.1 channels, and at the depolarizing Ca_V1.2 and Na_V1.5 channels fell within a narrow half-log 3-10 µM concentration range, suggesting that mutual compensation could explain the satisfactory arrhythmogenic cardio-safety profile of clozapine. Although the IC₅₀ values determined herein using an automated patch-clamp (APC) technique are at the higher end of clozapine plasmatic concentrations at target therapeutic doses, this effective antipsychotic appears prone to distribute preferentially into the cardiac tissue, which supports the clinical relevance of our in vitro pharmacological findings.

Development and validation of a risk prediction nomogram for disposition of acute clozapine intoxicated patients to intensive care unit

BACKGROUND

Clozapine is an atypical antipsychotic drug used for the treatment of refractory schizophrenia. It is reported as the most toxic in its class. Using serum clozapine level as a severity indicator is doubtful and unfeasible, particularly in low resourced countries.

METHODS

This is an extended two-phase retrospective study that utilized medical records of patients diagnosed with acute clozapine intoxication and admitted to Tanta University Poison Control Center, Egypt during the past 6 years. Two hundred and eight medical records were used to establish and validate a nomogram for predicting the need for intensive care unit (ICU) admission in acute clozapine intoxicated patients.

RESULTS

A reliable simple bedside nomogram was developed and proved its significant ability to predict the need for ICU admission, with an area under the curve (AUC) of 83.9% and 80.8% accuracy. It encompassed the age of admitted patients (AUC = 64.8%, p = .003), respiratory rate (AUC = 74.7%, p < .001), O₂ saturation (AUC = 71.7%, p < .001), and random blood glucose level upon admission (AUC = 70.5%, p < .001). External validation of the proposed nomogram showed a high AUC (99.2%) with an overall accuracy of 96.2%.

CONCLUSION

There is a need to develop a reliable objective tool predicting the severity and need for ICU admission in acute clozapine intoxication. The proposed nomogram is a substantially valuable tool to estimate ICU admission probabilities among patients with acute clozapine intoxication and will help clinical toxicologists make rapid decisions for ICU admission, especially in countries with low resources.

Fatal poisonings involving clozapine: A 16-year review of Australian coronial investigations

OBJECTIVE

Concerns about intentional and unintentional poisoning present a barrier to wider use of clozapine in treatment-resistant schizophrenia. The objective of this study was to investigate decedent demographics and trends in fatal poisonings in Australia involving clozapine.

METHODS

This was a retrospective case series of all fatal drug toxicity reported to an Australian coroner between 1 May 2000 and 31 December 2016 where toxicological analysis detected clozapine. Cases were identified using the National Coronial Information System. Demographics extracted included age and gender of the decedent, year and location of death, cause and manner of death and drugs detected in post-mortem samples.

RESULTS

There were 278 poisoning deaths where clozapine was detected in toxicological analyses. Three-quarters of all cases (n = 207) involved men and the median age at death was 38.5 years (interquartile range: 16 years). Three-quarters of the deaths occurred in the home. Overall, 15.8% of deaths were deemed intentional, 57.5% unintentional and 24.5% of unknown intent. While the annual number of intentional self-poisonings remained constant with <5 per year, the overall number of fatalities increased due to an increase in unintentional poisonings. Multiple drug toxicity was reported in 55.0% of cases and clozapine alone in 45.0% of cases. The most common co-reported medications were antidepressants, benzodiazepines and opioids detected in 47.1%, 44.4% and 41.2% of multiple drug toxicities, respectively.

CONCLUSION

This was the first Australia-wide review of all fatal drug poisonings reported to a coroner involving clozapine. Fatalities were most common in men and occurred at home. Multiple drug toxicity generally involved psychotropic, sedative or opioid analgesic medications. Despite increasing clozapine use, rates of intentional poisoning have remained constant and low. Developing a better knowledge of unintentional fatalities presents an opportunity to minimise harm.

A Real-World Study of Risk Factors for QTc Prolongation in Schizophrenia Patients Receiving Atypical Antipsychotics

PURPOSE

The risk of sudden cardiac death in patients receiving atypical antipsychotics may be related to QTc prolongation. The aim of this study was to investigate the risk factors for QTc prolongation to prevent QTc prolongation and guide clinical practice.

METHODS

All electrocardiogram recordings of 913 schizophrenia patients who were receiving atypical antipsychotics were reviewed for prolonged QTc and associated conditions. Binary logistic regression analysis was used to investigate risk factors for QTc prolongation.

RESULTS

Logistic regression analysis demonstrated that sex (odds ratio [OR], 0.386; P = 0.010), age (OR, 1.047; P = 0.000), high-density lipoprotein (OR, 0.257; P = 0.014), and antipsychotics dose (OR, 1.040; P = 0.036) were significantly associated with QTc prolongation.

CONCLUSIONS

In patients with male sex, elder age, low high-density lipoprotein, or large antipsychotics dose, QTc should be monitored more frequently.

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.

[Vaccination Against COVID-19 in Patients Treated with Psychotropic Drugs]

Vaccines against SARS-CoV-2 have been available in the European Union since December 2020. Persons suffering from mental illness have an increased risk of a severe or fatal course following an infection with SARS-CoV-2. Thus, the question arises to what extent interactions between the newly approved vaccines and psychotropic drugs may be expected. Data on the tolerability and efficacy of vaccines against SARS-CoV-2 under treatment with psychotropic drugs are not available to date - however, potential interactions can be derived from previous investigations on vaccines against other pathogens, such as a reduced immune response with lower clinical efficacy and an increase in drug plasma levels due to the indirect vaccine-mediated inhibition of metabolizing enzymes. On the other hand, depressed patients treated with antidepressant medication show a better immune response.

Intravenous lipid emulsion as an adjuvant therapy of acute clozapine poisoning

Introduction:

Clozapine is a frequently prescribed atypical antipsychotic drug. Various case reports documented the successful recovery of acute antipsychotics toxicity in association with the administration of intralipid emulsion (ILE).

Aim:

This study aimed to assess the adjuvant therapeutic role of SMOF Lipid administration on the outcomes of acute clozapine poisoning.

Methods:

Forty patients with acute clozapine poisoning were randomly allocated into two equal groups. The control group received the standard supportive treatment only, whereas the intervention group received the standard supportive treatment plus SMOF Lipid 20% infusion. All patients were subjected to history taking, full clinical examination, and laboratory investigations. The study outcomes were evaluated.

Results:

The mean Glasgow Coma Scale (GCS) at 6 hours (13.1 ± 2.3 vs 9.2 ± 2, p < 0.001) and 12 hours (14.3 ± 1.5 vs 9.6 ± 2, p < 0.001) after admission was significantly higher in the intervention group compared to the control group. The intervention group showed a significantly lower frequency of prolonged QTc interval 12 hours after admission (p = 0.003), as well as a significantly shorter hospital stay (p < 0.001).

Conclusions:

SMOF Lipid infusion seemed to have improved GCS, the prolonged QTc interval, and shortened the length of hospital stay. Furthermore, there were no adverse effects related to its administration.

The systemic inflammatory response syndrome in acute antipsychotic poisoning

The purpose of this study was to investigate the mutual effect of systemic inflammatory response syndrome (SIRS) accompanied with fibrinolysis, endotoxemia, and coagulation in severe cases of antipsychotic poisoning. A total of 199 patients were examined, of which 71 were men and 128 were women. The age of the patients was from 22 to 63 years, (45.3 ± 6.1 years on average). According to the results of the course of therapy, the patients were divided into two groups. In the blood plasma, the content of C-reactive protein, fibrinogen and its proteolysis products (oligopeptides, D-dimers), interleukin-6 were determined. In the first 1 to 3 days, in group 1, the level of interleukin-6 decreased and approached the normal level (P ≤ .05). The opposite trend continued throughout the observation of patients from group 2-their levels of interleukin-6 increased day by day (P ≤ .05). The concentration of D-dimer already in 1 day after admission to intensive care in patients from group 2 exceeded the norm by 14 times (P ≤ .05). The level of D-dimer correlated with the level of oligopeptides in blood plasma upon admission, as well as for 3 and 5 days after admission to intensive care: 0.36, 0.76 at P ≤ .05, 0.94 at P ≤ .01, respectively. Similar correlations were obtained for the content of oligopeptides in urine and the level of D-dimer: 0.55, 0.85 at P ≤ .05, 0.93 at P ≤ .01. In this regard, the most pronounced correlation is that between the SIRS score, plasma D-dimer level, and the plasma level of the D-dimer derivatives, oligopeptides.

Focus on Clozapine Withdrawal- and Misuse-Related Cases as Reported to the European Medicines Agency (EMA) Pharmacovigilance Database

BACKGROUND

Clozapine is of high clinical relevance for the management of both treatment-resistant schizophrenia and psychotic disturbances with concurrent drug misuse. Although the molecule presents with a range of well-known side-effects, its discontinuation/withdrawal syndrome has been only anecdotally described.

AIMS

the 2005-2018 European Medicines Agency (EMA) dataset of Adverse Drug Reactions (ADRs) was analyzed to identify and describe possible clozapine withdrawal- and misuse-/abuse-/dependence-related issues.

METHOD

A descriptive analysis of clozapine-related ADRs was performed when available, data on ADRs' outcome, dosage, and possible concomitant drug(s) were considered.

RESULTS

Out of 11,847 clozapine-related ADRs, some 599 (5.05%) were related to misuse/abuse/dependence/withdrawal issues, including 258 withdrawal-related (43.1%); 241 abuse-related (40.2%); and 80 intentional product misuse-related (13.3%) ADRs. A small number of overdose- and suicide-related ADRs were reported as well. Clozapine was typically (69.2%) identified alone, and most (84.7%) fatalities/high-dosage intake instances were reported in association with a history of substance abuse.

CONCLUSIONS

Previous suggestions about the possibility of a clozapine discontinuation/withdrawal occurrence are here supported, but further studies are needed. However, the misuse/abuse cases here identified might be difficult to interpret, given the lack of studies highlighting the possible recreational use of clozapine. The high-dosage intake, fatal outcomes and clozapine/polydrug abuse issues reported here may, however, be a reason for concern.

Delayed complications after severe clozapine intoxication: a case report. The pharmacokinetic profile of clozapine and it's important role in the course of symptoms

Clozapine intoxications have a varied clinical presentation and may have severe complications. Management and treatment guidelines rarely highlight the risks of delayed clinical presentations. We present the case of a 50-year-old man showing severe complications 15 hours after intoxication with 4200 mg clozapine. Treatment consisted of strict monitoring, including vital support and regular clozapine blood levels. Clinical presentations may be delayed up to 5 days after intoxication, for which strict monitoring of clinical symptoms and vital functions during this period is of major importance. We discuss the clinical course of clozapine intoxication, the value of sampling clozapine blood levels and provide an overview of the current treatment guidelines, which we suggest to update to include the management of delayed complications.

Preliminary study of higher-order language and extralinguistic impairments in individuals with high clinical risk of psychosis and first episode of schizophrenia

AIM

Higher-order language functions are associated with understanding indirect speech acts, lexical-semantic processes, the understanding and production of prosody, discourse production and comprehension. Only a few studies imply that language abnormalities may be present in individuals at ultra-high risk for psychosis (UHR) and first-episode of schizophrenia (FE). The purpose of this study was to test the presence of higher-order language dysfunctions in UHR and FE subjects using a standardized comprehensive test battery.

METHODS

Twenty patients experiencing FE schizophrenia, 33 UHR individuals and 20 healthy controls (HC) took part in the study. Higher-order language and extralinguistic abilities were evaluated using the Right Hemisphere Language Battery (RHLB-PL). The battery consisted of tests covering the comprehension of implicit information, lexico-semantic processing, understanding humour, making inappropriate remarks and comments, understanding and explaining metaphors, understanding prosody and appropriateness of behaviour in communication settings.

RESULTS

The UHR patients scored lower than HC when comprehending implicit information, discourse and in areas associated with the effectiveness of interpersonal communication; however, they scored higher than the FE participants in explanation of metaphors and processing language information in the context of general knowledge. The FE participants scored lower than healthy controls in comprehension of implicit information, explanation of metaphors, discourse understanding, processing language information in the context of general knowledge and effectiveness of interpersonal communication.

CONCLUSIONS

The higher-order language dysfunctions mediated by the right hemisphere appear to be present in subjects at UHR of schizophrenia and those experiencing their FE. The results may play a crucial role in diagnostic processes.

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.

Antipsychotic drug poisoning monitoring of clozapine in urine by using coffee ring effect based surface-enhanced Raman spectroscopy

Antipsychotics are the drugs most often involved in drug poisoning cases, and therefore, therapeutic drug monitoring (TDM) is necessary for safe and effective medication administration of these drugs. In this study, a coffee ring effect-based surface-enhanced Raman spectroscopy (CRE-SERS) method was developed and successfully used to monitor antipsychotic poisoning by using urine samples for the first time. The established method exhibited excellent SERS performance since more hot spots were obtained in the "coffee ring". Using the optimized CRE-SERS method, the sensitivity was improved one order more than that of the conventional method with reasonable reproducibility. The antipsychotic drug clozapine (CLO) spiked into urine samples at 0.5-50 μg mL^-1 was quantitatively detected, at concentrations above the thresholds for toxicity. The CRE-SERS method allowed CLO and its metabolites to be ultimately distinguished from real poisoning urine samples. The coffee-ring effect would provide more opportunities for practical applications of the SERS-based method. The frequent occurrence of drug poisoning may have created a new area for the application of the CRE-SERS method. It is anticipated that the developed method will also have great potential for other drug poisoning 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.

Polypharmacy in the elderly from the clinical toxicologist perspective

INTRODUCTION

Polypharmacy is closely associated with multimorbidity in the elderly and can lead to problems and drug interactions.

AIM

This study assessed polypharmacy in the elderly, tracking inquiries to the Poison Information Centre Nuremberg (PICN) and patients needing toxicological intensive care therapy.

METHODS

From 2006-2009, all PICN inquiries involving individuals > 70 years were tracked, as were cases at the Toxicological Intensive Care Unit (T-ICU) regarding adverse drug reactions (ADRs) and drug poisoning.

RESULTS

Of 11,683 PICN calls about pharmaceuticals, 175 (1.5%) were from people > 70 years; 156 (4.8%) of 3,272 T-ICU patients were > 70 years. Calls about psychopharmaceuticals (46.9%) and analgesics (25.7%) were most frequent. Among the T-ICU patients, psychopharmaceuticals like sedatives and hypnotics were frequently involved (20.5%), as were tricyclic antidepressants (17.9%) and analgesics (29.5%). Ethanol was co-ingested by 18.3%.

CONCLUSION

Population-specific poison prevention strategies are needed to reduce toxic exposures. Such strategies could include pharmacist intervention, improved prescriber communication and education regarding the geriatric population, and computerized drug databases.

Optimizing clozapine treatment

OBJECTIVE

Clozapine treatment remains the gold standard for treatment-resistant schizophrenia, but treatment with clozapine is associated with several side-effects that complicate the use of the drug. This clinical overview aims to provide psychiatrists with knowledge about how to optimize clozapine treatment. Relevant strategies for reducing side-effects and increasing the likelihood of response are discussed.

METHOD

Studies of clozapine available in MEDLINE were reviewed.

RESULTS

A slow up-titration of clozapine is recommended in order to reach the optimal dosage of clozapine and diminish the risk of dose-dependent side-effects. Particularly, in case of partial response or non-response, the use of therapeutic drug monitoring of clozapine is recommended. Plasma levels above the therapeutic threshold of 350-420 ng/ml are necessary to determine non-response to clozapine. To ease the burden of dose-dependent side-effects, dose reduction of clozapine should be tried and combination with another antipsychotic drug may facilitate further dose reduction. For most side-effects, counteracting medication exists. Augmentation with lamotrigine, antipsychotics, or electroconvulsive therapy may be beneficial in case of partial response to clozapine.

CONCLUSION

Treatment with clozapine should be optimized in order to increase the rate of response and to minimize side-effects, thus diminishing the risk of discontinuation and psychotic relapse.