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Editorial
Canadian Journal of Psychiatry: New Editor and New Policies
Joel Paris, MD
(PDF)

Guest Editorial
Risk Assessment in Psychiatric Practice
Kenneth Hashman, MD, FRCPC, DABPN
(PDF)

In Review
The Canadian Contribution to Violence Risk Assessment: History and Implications for Current Psychiatric Practice
Hy Bloom, LLB, MD, Christopher Webster, PhD, Stephen Hucker, MB, Karen De Freitas, MD
(PDF)

The Clinical Use of Risk Assessment
Graham D Glancy, MB, ChB, FRCPsych, FRCPC, Gary Chaimowitz, MB, ChB, FRCPC
(PDF)

The State of Contemporary Risk Assessment Research
Michael A Norko, MD, Madelon V Baranoski, PhD
(PDF)

Review Paper
Community Treatment Orders: Profile of a Canadian Experience
Ann-Marie A O’Brien, MSW, RSW, Susan J Farrell, PhD, CPsych*
(PDF)

International Dosage Differences in Fluoxetine Clinical Trials
Scott Patten, MD, Andrea Cipriani, MD, Paolo Brambilla, MD3, Michela Nosè, MD, Corrado Barbui, MD
(PDF)

Original Research
Panic-Agoraphobic Spectrum and Light Sensitivity in a General Population Sample in Italy
Letizia Bossini, MD, Mirko Martinucci, MD, Katia Paolini, MD, Paolo Castrogiovanni, MD
(PDF)

Psychotic Disorders Clinic and First-Episode Psychosis: A Program Evaluation
Suzanne Archie, MD, FRCPC, Jane Hamilton Wilson, RN, Kevin Woodward, BSc, Heather Hobbs, RN, Shelley Osborne, RN, Jean McNiven, RN
(PDF)

Screening for Mild Cognitive Impairment: Comparing the SMMSE and the ABCS
D William Molloy, MB, MRCPI, FRCPC, Timothy IM Standish, David L Lewis, PhD
(PDF)

Attention-Deficit Hyperactivity Disorder With and Without Obsessive–Compulsive Behaviours: Clinical Characteristics, Cognitive Assessment, and Risk Factors
Paul Daniel Arnold, MD, FRCPC, Abel Ickowicz, MD, FRCPC, Shirley Chen, MD, MPH, Russell Schachar, MD, FRCPC
(PDF)

Brief Communication
Validation de la version française de l’inventaire de détresse péritraumatique
Louis Jehel, MD, PhD, Alain Brunet, PhD, Sabrina Paterniti, MD, PhD, Julien D Guelfi, MD, Pr
(PDF)

Book Reviews
(PDF)

The Confinement of the Insane: International Perspectives, 1800–1965
Review by
Laurence Jerome, MD

Suicide in Children and Adolescents
Review by
Paul S Links, MD, FRCPC

Letters to the Editor
(PDF)

A Novel Form of Treatment Resistance in Anorexia Nervosa

Capgras Syndrome in the Modern Era: Self Misidentification on an ID Picture

Effectiveness of Risperidone in Delirium

Family-Oriented Rehabilitation for Unexplained Chronic Pain

Hypokalemia from Risperidone and Quetiapine Overdose

A Renewed Interest in Day Treatment

Quetiapine Therapy for Corticosteroid-Induced Mania

Letters to the Editor

Hypokalemia from Risperidone and Quetiapine Overdose

Dear Editor: Hypokalemia has been listed as one of the known toxic effects of both quetiapine and risperidone. It is a risk factor for potentially life-threatening arrhythmias like torsades de pointes, caused by a prolonged QT interval—another side-effect of antipsychotic drugs, including quetiapine (1). There is a solitary report of mild hypokalemia following a quetiapine overdose of 9600 mg (2). Here, we report a case of remarkable hypokalemia following a much smaller dose of quetiapine and risperidone.

Case Report

Mr B, a white man aged 44 years, had a diagnosis of bipolar disorder not otherwise specified. He was taking risperidone 3 mg daily, lithium carbonate 900 mg daily, and quetiapine 50 mg at bedtime. At about 20:30 hours on the night of presentation, he attempted suicide by taking approximately 750 mg of quetiapine and between 90 and 120 mg of risperidone.

He denied taking lithium in his attempt. This was substantiated by a subsequent test that revealed a lithium level of 0.4 mmol/L.

He presented to the emergency room about 2 hours after the ingestion and was stabilized medically. Initial labs drawn at the time of emergency department presentation showed potassium levels of 2.9 mmol/L and magnesium levels of 1.7 mg/dL (with lower normal levels being 1.8 mg/dL). His potassium level was initially corrected with intravenous cocktails in the emergency department and intensive care unit and was followed over the next few days. It subsequently plateaued and remained stable and in the normal range. Mr B recovered fully and was discharged home after a brief hospital stay.

Discussion

Both risperidone and quetiapine can cause hypokalemia. However, at about 350 mg or more, the risperidone dose reported to cause hypokalemia is much higher than that taken by Mr B. The previously reported case of hypokalemia following quetiapine overdose found a potassium level of 3.3 mmol/L after ingestion of 9600 mg (2). Our patient ingested only about 750 mg of quetiapine and about 100 mg of risperidone. Could it be that the drugs acted synergistically to cause a more dramatic hypokalemia? Although exact mechanisms of action are not clear, it is possible that both drugs cause a more dramatic drop in serum potassium following acute ingestion, which would further increase the chances of torsades de pointes and sudden cardiac death secondary to concomitant QT interval prolongation.

This case demonstrates that we need to be vigilant after an apparently nonlethal overdose of 2 drugs having a relatively safe overdose profile, both for possible synergistic effects of the 2 drugs on serum electrolytes and for the possible ensuing complications.

Funding and Support

None of the authors have any personal or professional connection to the drug companies or products mentioned above.

References

1. Welch R, Chue P. Antipsychotic agents and QT changes. J Psychiatry Neurosci 2000;25:154–60.

2. Hustey FM. Acute quetiapine poisoning. J Emerg Med 1999;17:995–7.

Asif R Malik, MD,
Pamela K Wolf, Pharm D, BCPP
Saj Ravasia, MD, CCFP, FRCPC, DABPN
Fargo, North Dakota