Intentional Self-Poisoning With the Chlorophenoxy Herbicide 4-Chloro-2-Methylphenoxyacetic Acid (MCPA) - 18/08/11

Doi : 10.1016/j.annemergmed.2005.03.016

Darren M. Roberts, MBBS ^⁎ , Ruwan Seneviratne, MBBS, Fahim Mohammed, BPharm, Renu Patel, BSc, Lalith Senarathna, BSc, Ariyasena Hittarage, MD, MRCP, Nick A. Buckley, MD, FRACP, Andrew H. Dawson, MBBS, FRACP, Michael Eddleston
From the South Asian Clinical Toxicology Research Collaboration, Medical School, Australian National University, Acton, Australian Capital Territory, Australia (Roberts, Buckley); the South Asian Clinical Toxicology Research Collaboration Clinical Units, Anuradhapura and Polonnanuwa Hospitals, North Central Province, Sri Lanka (Roberts, Seneviratne, Mohammed, Senarathna, Dawson, Eddleston); the Queensland Health Scientific Services, Coopers Plains, Queensland, Australia (Patel); the Anuradhapura General Hospital, Anuradhapura, North Central Province, Sri Lanka (Hittarage); Faculty of Medicine, University of Peradeniya, Peradeniya, Sri Lanka (Dawson); the Department of Clinical Medicine, Faculty of Medicine, University of Colombo, Col-07, Sri Lanka (Eddleston); and the Department of Tropical Medicine, Oxford University, Oxford, United Kingdom (Eddleston)

Address for correspondence: Darren M. Roberts, MBBS, South Asian Clinical Toxicology Research Collaboration, Medical School, Australian National University, Australian Capital Territory, Australia; +94 776 185 026, Fax +94 25 2222 147

Abstract

Study objective

Data on poisoning with MCPA (4-chloro-2-methyl-phenoxyacetic acid) are limited to 6 case reports. Our objective is to describe outcomes from intentional self-poisoning with MCPA in a prospective case series of 181 patients presenting to hospitals in Sri Lanka.

Methods

Patient information was collected by on-site study physicians as part of an ongoing prospective cohort study of poisoned patients. Medical history, clinical details, and blood samples were obtained prospectively.

Results

Overall clinical toxicity was minimal in 85% of patients, including mild gastrointestinal symptoms in 44% of patients. More severe clinical signs of chlorophenoxy poisoning reported previously, such as rhabdomyolysis, renal dysfunction, and coma, also occurred but were uncommon. Eight patients died (4.4%). Most deaths occurred suddenly from cardiorespiratory arrest within 48 hours of poisoning; the pathophysiological mechanism of death was not apparent. The correlation between admission plasma MCPA concentration and clinical markers of severity of toxicity (physical signs, symptoms, and increased creatine kinase level) was poor.

Conclusion

Intentional self-poisoning with MCPA generally causes mild toxicity, but cardiorespiratory arrest and death may occur. All patients should receive routine resuscitation and supportive care. It seems reasonable to correct acidosis and maintain an adequate urine output, but there is insufficient evidence to support other specific interventions. Our data do not support a clinical role for measurement of plasma MCPA in the acute management of poisoning, and insufficient data were available to fully examine the utility of measured electrolytes and creatine kinase levels.

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Plan

Introduction

Background

Importance

Goals of This Investigation

Materials and Methods

Study Design

Setting

Selection of Participants

Interventions

Data Collection and Processing

Results

Limitations

Discussion

Supervising editor: Richard C. Dart, MD, PhD
Author contributions: NAB and ME designed the randomized controlled trial and obtained research funding. ME established the trial and recruited hospitals. FM, LS, and ME supervised the conduct of the trial, data collection, and data management. DMR coordinated data retrieval with the assistance of RS, FM, and LS. DMR conducted the primary analysis, liaised with the analytical laboratory, reviewed medical charts, performed the literature search, and drafted the manuscript. RP provided advice on laboratory analyses and takes responsibility for these results. AH was responsible for the clinical care of the patients. NAB, AHD, and ME provided statistical advice and assisted with data interpretation. All authors approved the final version. DMR takes responsibility for the paper as a whole.
Funding and support: DMR is funded by a scholarship from the National Health and Medical Research Council (Australia). ME is a Wellcome Trust Career Development Fellow, funded by grant GR063560MA from the Wellcome Trust's Tropical Interest Group. The South Asian Clinical Toxicology Research Collaboration is funded by a Wellcome Trust/National Health and Medical Research Council International Collaborative Research Grant GR071669MA.
Presented at the CPT2004 (Clinical Pharmacology and Therapeutics 2004) international meeting, August 2004, Brisbane, Australia.
Reprints not available from the authors.