No evidence that WHO-recommended treatment for insecticide poisoning improves survival

June 29, 2009

A study published this week in the open access journal PLoS Medicine finds no evidence to suggest that a controversial antidote recommended by the World Health Organisation (WHO) to treat patients poisoned with highly toxic insecticides improves their chance of survival. The results may even add weight to existing concerns about pralidoxime, the treatment recommended by the WHO, by suggesting that it could be harmful in patients who have deliberately poisoned themselves with insecticides.

Poisoning with organophosphorous pesticides - toxic chemicals commonly used in agriculture in developing countries is a global public health problem causing an estimated 200,000 deaths a year. Deliberate self-poisoning with pesticides is a common method of suicide in some countries- in Sri Lanka, more than 50% of fatal suicide attempts are a result of pesticide poisoning. Michael Eddleston, from the University of Edinburgh, and colleagues conducted a clinical trial to study the effects of WHO-recommended pralidoxime treatment in patients who had been admitted to two hospitals in Sri Lanka for insecticide self-poisoning. If ingested by humans the pesticides disrupt the communication between the brain and body, inhibiting the activity of a neurotransmitter called acetylcholine, which plays a crucial role in the central nervous system and the control of breathing. To treat organophosphate poisoning, the WHO recommends that in addition to atropine, an antidote that is known to reverse some but not all of the effects of the poisoning, a regimen of pralidoxime should be used to reactivate acetylcholine activity. As the authors of this study mention, few randomized clinical trials have been conducted into its use, meaning that there is a lack of evidence for its effectiveness, in particular relating to dosage.

The researchers enrolled 235 patients at two Sri Lankan hospitals who had self-poisoned with organophosphate insecticides, determining how much, and which, pesticide each patient had been exposed to, and randomly allocating them to receive either the WHO-recommended regimen of pralidoxime or a salt water placebo. However, the trial was stopped early and did not reach its intended study size owing to discussions surrounding the results of another trial of pralidoxime therapy, carried out in India at the same time which led to a fall-off in recruitment of patients. In the Sri Lankan trial, published in PLoS Medicine, more patients in the pralidoxime arm died than in the placebo arm, despite the fact that pralidoxime was shown to aid acetylcholine activity. Whilst the difference in mortality between arms was not statistically significant, it is suggestive of a higher mortality rate resulting from pralidoxime treatment.

Acknowledging the difficult situation that clinicians now face when deciding whether or not to administer pralidoxime to patients poisoned with organophosphorous pesticides, the authors conclude that there is no consistent clinical evidence for the use of pralidoxime in patients who have self-poisoned with organophosphorous pesticides. They argue that further trials are needed to explore the risks and benefits of oximes and dosing regimens.
-end-
Funding: ME is a Wellcome Trust Career Development Fellow. This work was funded by grant 063560 from the Wellcome Trust's Tropical Interest Group to ME. The South Asian Clinical Toxicology Research Collaboration is funded by a Wellcome Trust/National Health and Medical Research Council International Collaborative Research Grant 071669. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Citation: Eddleston M, Eyer P, Worek F, Juszczak E, Alder N, et al. (2009) Pralidoxime in Acute Organophosphorus Insecticide Poisoning--A Randomised Controlled Trial. PLoS Med 6(6): e1000104. doi:10.1371/journal.pmed.1000104

IN YOUR COVERAGE PLEASE USE THIS URL TO PROVIDE ACCESS TO THE FREELY AVAILABLE PAPER: http://medicine.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pmed.1000104

PRESS-ONLY PREVIEW OF THE ARTICLE: http://www.plos.org/press/plme-06-06-eddleston.pdf

CONTACT:
Michael Eddleston
University of Edinburgh
Clinical Pharmacology Unit
QMRI
Edinburgh, EH16 4TJ
United Kingdom
+44 131 242 9214
eddlestonm@yahoo.com

PLOS

Related Pesticides Articles from Brightsurf:

More plant diversity, less pesticides
Increasing plant diversity enhances the natural control of insect herbivory in grasslands.

In pursuit of alternative pesticides
Controlling crop pests is a key element of agriculture worldwide, but the environmental impact of insecticides is a growing concern.

Two pesticides approved for use in US harmful to bees
A previously banned insecticide, which was approved for agricultural use last year in the United States, is harmful for bees and other beneficial insects that are crucial for agriculture, and a second pesticide in widespread use also harms these insects.

Dingoes have gotten bigger over the last 80 years - and pesticides might be to blame
The average size of a dingo is increasing, but only in areas where poison-baits are used, a collaborative study led by UNSW Sydney shows.

Pesticides can protect crops from hydrophobic pollutants
Researchers have revealed that commercial pesticides can be applied to crops in the Cucurbitaceae family to decrease their accumulation of hydrophobic pollutants, thereby improving crop safety.

Honeybee lives shortened after exposure to two widely used pesticides
The lives of honeybees are shortened -- with evidence of physiological stress -- when they are exposed to the suggested application rates of two commercially available and widely used pesticides.

Pesticides increase the risk of schistosomiasis, a tropical disease
Schistosomiasis is a severe infectious disease caused by parasitic worms.

A proposal to change environmental risk assessment for pesticides
Despite regulatory frameworks designed to prevent environmental damage, pesticide use is still linked to declines in insects, birds and aquatic species, an outcome that raises questions about the efficacy of current regulatory procedures.

SDHI pesticides are toxic for human cells
French scientists led by a CNRS researcher have just revealed that eight succinate dehydrogenase inhibitor pesticide molecules do not just inhibit the SDH activity of fungi, but can also block that of earthworms, bees, and human cells in varying proportions.

Pesticides deliver a one-two punch to honey bees
A new paper in Environmental Toxicology and Chemistry reveals that adjuvants, chemicals commonly added to pesticides, amplify toxicity affecting mortality rates, flight intensity, colony intensity, and pupae development in honey bees.

Read More: Pesticides News and Pesticides Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.