Covert clozapine overdose: Clozapine toxicity in a naive patient

Antipsychotic-Related Fatal Poisoning, England and Wales, 1993-2019: The Impact of Second-Generation Antipsychotics

BACKGROUND

Deaths from antipsychotic (AP) poisoning have increased in England and Wales despite restriction of the use of thioridazine in 2000.

METHODS

We analyzed data from the Office for National Statistics drug-related death database, England and Wales, 1993-2019, to investigate fatal AP poisoning.

RESULTS

There were 2286 deaths (62% male patients). Annual numbers of intentional AP-related fatal poisonings (suicides) were relatively stable (1993, 35; 2019, 44; median, 44; range, 30-60). Intentional overdose deaths involving clozapine (96 male, 25 female) increased from 1 in 1994 to 5 in 2003 and have since remained relatively constant (median, 6; range, 3-10 per annum). Unintentional second-generation AP-related fatal poisonings have increased steadily since 1998, featuring in 828 (74%) of all unintentional, AP-related fatal poisonings in the period studied (2019, 89%). There were 181 unintentional clozapine-related deaths, (107 [59%] alone without other drugs ± alcohol) as compared with 291 quetiapine-related deaths (86 [30%] alone without other drugs ± alcohol) and 314 unintentional olanzapine-related deaths (77 [25%] alone without other drugs ± alcohol). Some 75% of all unintentional clozapine- and olanzapine-related deaths were of male patients (78% and 73%, respectively) as compared with 58% of unintentional quetiapine-related fatal poisonings. Clozapine now features prominently in intentional and in unintentional AP-related fatal poisoning in England and Wales. Deaths of male patients predominate in both categories. There were also 77 and 86 deaths attributed to unintentional poisoning with olanzapine and with quetiapine, respectively, in the absence of other drugs.

CONCLUSIONS

More effort is needed to prevent unintentional deaths not only from clozapine but also from olanzapine and quetiapine.

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.

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.