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.

Clinical toxicology: clinical science to public health

1. The aims of the present paper are to: (i) review progress in clinical toxicology over the past 40 years and to place it in the context of modern health care by describing its development; and (ii) illustrate the use of clinical toxicology data from Scotland, in particular, as a tool for informing clinical care and public health policy with respect to drugs. 2. A historical literature review was conducted with amalgamation and comparison of a series of published and unpublished clinical toxicology datasets from NPIS Edinburgh and other sources. 3. Clinical databases within poisons treatment centres offer an important method of collecting data on the clinical effects of drugs in overdose. These data can be used to increase knowledge on drug toxicity mechanisms that inform licensing decisions, contribute to evidence-based care and clinical management. Combination of this material with national morbidity datasets provides another valuable approach that can inform public health prevention strategies. 4. In conclusion, clinical toxicology datasets offer clinical pharmacologists a new study area. Clinical toxicology treatment units and poisons information services offer an important health resource.

Delayed Respiratory Depression After Risperidone Overdose

Risperidone is an atypical antipsychotic drug used for the treatment of schizophrenia. Both positive and negative symptoms are prominent with its use. Metabolism occurs mainly in the liver, where risperidone is changed by CUP2D6 to an active metabolite, 9-hydroxyrisperidone. The half-lives of risperidone and its metabolite are 3 and 7 h, respectively. Genetic polymorphism is seen in the 6%-8% of white patients who are considered poor metabolizers. In poor metabolizers, the half-life extends to 20-30 h. We present an unusual case of unanticipated delayed respiratory depression after risperidone overdose.

Fatal poisoning with antipsychotic drugs, England and Wales 1993-2002

Prescription of atypical antipsychotics has increased in recent years. There have also been changes in the guidance on using older drugs, particularly the restriction in the use of thioridazine. We analysed deaths due to poisoning involving antipsychotics in England and Wales, 1993-2002, by age, sex, intent, and agents involved. We also studied antipsychotic prescribing in the community and poisoning deaths in England. Deaths attributed to adverse reactions in the course of normal treatment were not studied because these deaths are not classified as 'poisonings'. The number of deaths involving antipsychotics increased from around 55 per year 1993-1998 to 74 in 2000, and then fell to 53 in 2002. Around 25% of deaths had a verdict of accidental death and in about 60% of deaths a verdict of suicide or an open verdict was recorded. There were no deaths involving thioridazine in 2002, following its removal from use in 2001. However, the number of deaths associated with atypicals, most notably olanzapine and clozapine, has increased. Age-specific death rates were highest in those aged 30-39 and 40-49 years, and were very low in those aged under 20 and 70 or over. Death rates in males were greater than in females. For many drugs the proportion mentions either alone or with ethanol, was 25-45%, but for clozapine and olanzapine such mentions totalled 65-69%. Deaths per million prescriptions (clozapine excluded) were highest for quetiapine (31.3 per million), chlorpromazine (29.4 per million) and thioridazine (15.5 per million).

Ziprasidone Overdose: Cases Recorded in the Database of Pfizer-Spain and Literature Review

Ziprasidone is an atypical antipsychotic with a highly specific receptorbinding profile that has been shown to be effective for both positive and negative symptoms of schizophrenia. The agent has been associated with a low frequency of extrapyramidal symptoms and sedative and anticholinergic effects. Four cases of acute ziprasidone overdose were recorded in the database of the department of pharmacovigilance of Pfizer-Spain from January 2003 (when ziprasidone was first marketed in Spain) to October 2004. The doses taken were 780, 1120, 4400, and 4480 mg. In two cases, an excessive ingestion of other drugs such as benzodiazepines and sedative hypnotics was also noted. None of the four cases showed cardiac adverse effects, and the QTc interval was within the normal range in all patients. No relevant neurologic clinical signs were observed, except for mild drowsiness in three cases. Evaluation of these four cases, as well as review of the literature, showed that an overdose of ziprasidone alone, in patients without risk factors that contraindicate its use, is relatively safe.

Overdose of aripiprazole, a new type of antipsychotic

Aripiprazole is the first member of a new class of antipsychotic medications. Unlike other antipsychotics, it acts as a partial agonist at dopamine D(2) and 5-HT(1A) receptors, thereby mitigating most of the adverse reactions such as extrapyramidal side effects and hyperprolactinemia. Additionally, most research to date has suggested a low incidence of QTc prolongation and orthostatic hypotension at therapeutic doses. Experience in the setting of intentional overdose, however, is limited. We present a case of a 27-year-old woman who intentionally ingested 330 mg of aripiprazole in a suicide attempt. Clinical effects were limited to mild sedation. Serum levels performed by the drug's manufacturer confirmed a total level (parent drug and active metabolite) of 716 ng/mL, nearly six times the upper limit of accepted therapeutic levels. This suggests that aripiprazole's therapeutic index is quite high and reinforces the drug's known safety profile.

Case Studies of Postmortem Quetiapine: Therapeutic or Toxic Concentrations?

The focus of this study was to determine if the analysis of a variety of postmortem biological specimens would aid in the toxicological interpretation of quetiapine in the cause and manner of death determinations. Postmortem quetiapine concentrations were examined in 21 medical examiner cases using liquid-liquid extraction and high-performance liquid chromatography analysis. Specimens analyzed were peripheral blood, central blood, liver, vitreous humor, and gastric contents, when available. Findings from this study suggest that therapeutic postmortem quetiapine concentrations may be less than 1 mg/L in both peripheral and central blood, less than 0.5 mg/L in vitreous, and less than 5 mg/kg in liver. Quetiapine concentrations indicative of toxicity were estimated at greater than 1 mg/L in peripheral and central blood, greater than 0.5 mg/L in vitreous, and greater than 5 mg/kg in the liver. Liver concentrations appeared to be particularly helpful in determining the potential for toxicity when compared with blood concentrations. Cases in which quetiapine was determined to play a significant role in the death indicated postmortem liver concentrations greater than 5 mg/kg. Cases in which quetiapine concentrations were considered incidental or noncontributory in the death had liver concentrations 2 mg/kg or less.

Postmortem tissue distribution of olanzapine and citalopram in a drug intoxication

A 40-year-old white male was found dead in bed in a group home for mentally ill adults. The decedent had been diagnosed a paranoid schizophrenic. An autopsy was performed at the Office of the Cuyahoga County Coroner in Cleveland, Ohio. Toxicological testing detected olanzapine and citalopram in post mortem specimens. Multiple fluids and tissues were assayed by liquid-liquid extraction followed by gas chromatography with nitrogen phosphorus detection, and qualitative confirmation by electron impact gas chromatography/mass spectrometry. Drug concentrations [olanzapine: citalopram; mg/L or mg/Kg] determined in this case are the highest reported to date involving these drugs- 1.38:3.35 heart blood, 1.11:1.65 femoral blood, 60.24:32.43 urine, 6.47:10:71 liver, and 38.36:49.16 lung, respectively. Drug concentrations in tissues were found to be the highest in lung for both drugs and lowest in the heart. Citalopram but not olanzapine was detected in bone. The cause of death was ruled acute intoxication by the combined effects of olanzapine and citalopram and the manner, accident.

Tissue distribution of molidone in a multidrug overdose

Molindone hydrochloride (Moban) is a dihydroindolone compound dissimilar in structure to other antipsychotic drugs (i.e., phenothiazines, butyrophenones, dibenzepines, and thioxanthenes). The antipsychotic (or neuroleptic) activity of molindone makes it particularly useful in the treatment of schizophrenia. There are a few published cases which report the tissue distribution of molindone in the human body. We report the analysis of molindone in postmortem samples using a solvent mixture (toluene/hexane/isoamyl alcohol) base extract followed by an acid (0.5M H(2)SO(4)) wash. Molindone was identified by gas chromatography-mass spectrometry (m/z 100, 176, 276) and quantitated using a gas chromatograph and nitrogen-phosphorus detector. The range of linearity was 0.1 mg/L to 5.0 mg/L. We report our findings of molindone concentrations in blood, liver, bile, gastric, and urine as follows: 6 mg/L in blood; 26 mg/kg in liver; 23.1 mg/L in bile; 1200 mg/L in gastric; and 37.3 mg/L in urine. Vitreous lithium (5.9 mmol/L) was determined by flame atomic absorption spectrometry. The medical examiner listed the cause of death as a combined drug overdose of molindone and lithium. The tissue results are compared with another case and the pharmacology of molindone is presented.

Disposition of quetiapine in biological specimens from postmortem cases

Quetiapine is a new atypical antipsychotic that was approved in 1997 by the U.S. Food and Drug Administration for the treatment of schizophrenia. It possesses a high affinity for 5-HT2 receptors and a low affinity for D1 and D2 dopamine receptors. Because quetiapine has only been released recently to the U.S. market, little information exists regarding therapeutic, toxic, and lethal concentrations. This study reports the detection of quetiapine in 13 postmortem cases. Following a basic liquid-liquid extraction, quetiapine was identified and quantitated by capillary gas chromatography with nitrogen phosphorus detection. Confirmation was accomplished by full scan electron impact gas chromatography/mass spectrometry. Heart blood quetiapine concentrations ranged from 0.07 to 18.37 mg/L (N = 12, mean +/- SD = 3.42 +/- 5.67, median 0.62) and femoral blood concentrations ranged from 0.06 to 19.25 mg/L (N = 10. mean +/- SD = 3.89 +/- 6.12, median 0.81). The average heart blood/femoral blood ratio was 1.31 (range 0.55 to 2.57, N = 10). Urine, bile, and gastric contents were assayed in all cases in which they were submitted. In three cases, the cause of death was determined to be quetiapine toxicity. In these cases heart blood concentrations ranged from 0.72 to 18.37 mg/L (N = 3). These data may provide a basis for establishing levels associated with quetiapine toxicity as well as therapeutic concentrations in postmortem specimens.

Aripiprazole (abilify) overdose in a child

Aripiprazole, 7-{4-[4-(2,3-dichlorophenyl)-1-piperazinyl] butyloxy}-3,4-dihydro-2(1H)-quinolinone, is an atypical antipsychotic medication inaugurating the newest class of atypical antipsychotics: the partial dopamine agonists. It has a particularly long half-life of elimination and variable metabolism secondary to genetic polymorphism. We report an unintentional overdose of 195 mg (17.1 mg/kg) of aripiprazole in a 2.5 year-old child. This patient exhibited CNS depression not requiring respiratory support and without significant cardiovascular effects. CNS effects persisted for almost 2 weeks postingestion.

Atypical experience: a case series of pediatric aripiprazole exposures

BACKGROUND

Aripiprazole is a new psychotropic agent that possesses a unique pharmacologic profile. The drug demonstrates mixed dopamine and serotonin agonist-antagonist activity and has been labeled a third-generation antipsychotic and dopamine-serotonin system stabilizer. Overdose experience is limited, especially in pediatrics.

CASE SERIES

Of five pediatric cases identified, toxicity was mainly evident in younger patients. A 2-year-old who ingested 40 mg experienced vomiting and significant lethargy lasting approximately 30 h. A 6-year-old who received two doses of aripiprazole therapeutically experienced lethargy, drooling, and flaccid facial muscles which improved with diphenhydramine. Two adolescents remained asymptomatic despite doses of 120 mg and 300 mg while a third adolescent with an unknown dose experienced transient lethargy.

CONCLUSION

Aripiprazole is capable of producing marked lethargy and gastrointestinal upset in pediatric patients. Adolescents in this series experienced only minor, if any, clinical effects. Major clinical effects, i.e., seizures, dysrhythmias, were not reported in this series.

[Clinical course of acute poisoning with olanzapine]

Olanzapine is a new atypical antipsychotic drug acting on different receptors. A variety of pharmacologic effects are responsible for toxicity and the variety of clinical symptoms seen in overdose: tachycardia, agitation or aggression, dysarthria, extrapyramidal dystonic effects, sedation or coma, small pupils, blurred vision, respiratory depression, hypotension. A retrospective analysis of clinical course of eight acute olanzapine intoxication treated at the Department of Clinical Toxicology Jagiellonian University Medical College is presented. CNS symptoms manifested in fluctuations between somnolence/coma and agitation/aggression and miosis were observed in most of the patients. Increased CPK activity was stated in the most of patients. All of the patients recovered, poisoning severity according PSS was moderate and severe.

[Sweets from the pharmaceutical industry reason to suspect intoxication with quetiapine]

A 13-year-old boy was presented to the emergency department with a presumed intoxication with quetiapine, an antipsychotic. The tablets turned out to be peppermints, used as advertisement gift from the pharmaceutical industry. This misunderstanding could have led to unnecessary treatment and observation of the patient in hospital, for a moderately serious intoxication.

Are 1 or 2 dangerous? Clozapine and olanzapine exposure in toddlers

Clozapine (Clozaril) and olanzapine (Zyprexa) are two relatively new atypical antipsychotics that are structurally and pharmacologically related. There are currently no therapeutic indications for these pharmaceuticals in infants and toddlers.Presumably, as the usage of these medications in adults increases, the frequency of unintentional pediatric ingestions will increase. In 2001 the annual report of the American Association of Poison Control Centers Toxic Exposure Surveillance System included a separate subcategory for atypical antipsychotics under the heading of sedatives/hypnotics/antipsychotics. The toxidrome resulting from these drugs is predominately central nervous system depression and anticholinergic effects. Although the desirable lack of extrapyramidal symptoms in adults results in their greatest clinical utility, several reports of toxic ingestions in small children are noteworthy for having extrapyramidal manifestations. We review here the available reported clinical experience with toxic doses of these medications that in small children may amount to as little as a single tablet. Although such doses may be lethal, supportive care and gastrointestinal decontamination in this population will generally lead to a good outcome.

Electrocardiogram and cardiovascular changes in thioridazine and chlorpromazine poisoning

OBJECTIVES

To examine the effects of anti-psychotic medications on cardiovascular parameters in overdose. Specifically, to examine dose-response relationships for thioridazine and chlorpromazine.

METHODS

A retrospective study of case records of patients presenting to the Edinburgh poisons treatment unit over 3 years (2000-2002). Information--including that on stated dose ingested, ECG parameters, and pulse and blood pressure--was extracted from case notes.

RESULTS

A total of 224 chlorpromazine, 96 thioridazine and 99 patients ingesting other anti-psychotics were evaluated. Full data on all aspects, both dose and cardiovascular change, was available in 96 chlorpromazine, 36 thioridazine and 27 of the other anti-psychotic cases. For thioridazine, there was a significant dose-response relationship for increasing heart rate and increasing QTc but not other cardiovascular changes. For chlorpromazine, there was no dose-response relationship for ECG changes, but there was a significant dose-response relationship for increasing heart rate and reduction in mean blood pressure.

CONCLUSIONS

We have confirmed a relationship between increasing dose of thioridazine and prolongation of QTc in overdose patients. No such change was observed with chlorpromazine. Both of these agents are reported to cause QT prolongation, but this study suggests that the nature of these effects is different for each agent. Poisoned patients may offer ways of exploring in more detail, and at a larger dose range, the effects of potentially cardiotoxic drugs in humans.

Fatal Overdoses Associated with Quetiapine

Quetiapine (Seroquel) is an atypical antipsychotic drug belonging to a new chemical class, the benzothiazepine derivatives. We present three cases from the Provincial Toxicology Center of British Columbia, Canada in which suicidal overdose deaths were associated with quetiapine. The blood specimens were initially subjected to a thorough qualitative analysis. Basic drugs were screened for by liquid-liquid extraction followed by gas chromatography-nitrogen-phosphorus (GC-NPD) and gas chromatography-mass spectrometry-electron impact detection utilizing both in-house and commercial search libraries. Acidic and neutral drugs were screened for by liquid-liquid extraction followed by high-performance liquid chromatography-diode-array detection. Volatiles were assayed by gas chromatography-flame-ionization detection. Quetiapine was assayed in biological specimens by basic extraction with n-butyl chloride and derivatized with 50 microL of MTBSTFA and separation by GC-NPD. Linearity was observed up to 2.0 mg/L. Samples with concentrations exceeding the linearity were diluted. These cases were chosen for study because they were all deaths as a result of suicidal ingestion of drugs in which quetiapine was considered a significant factor. The concentrations of quetiapine in these cases are 6-16 times greater than the upper reported therapeutic range (0.1-1.0 mg/L). In case #1, the concentrations of quetiapine found were 7.20 mg/L (19 micromol/L) in blood and 0.93 mg/L (2.4 micromol/L) in vitreous fluid. In case #2, the concentrations of quetiapine found were 16 mg/L in blood (42 micromol/L), 120 mg/kg (310 micromol/kg) in liver, and 1.8 mg/L (4.6 micromol/L) in vitreous fluid. In case #3, the concentrations of quetiapine found in femoral blood was 5.90 mg/L (15 micromol/L). In all cases, drugs in addition to quetiapine were detected, but in cases #1 and #2, the cause of death was considered to be a quetiapine overdose and the other drugs were not considered to be contributory. Case #3 was considered a mixed drug overdose.