Repeated pulse intramuscular injection of pralidoxime chloride in severe acute organophosphorus pesticide poisoning

Abstract

Objective

This study aimed to clarify the efficacy of 2 therapies for patients with severe acute organophosphorus pesticide poisoning, including atropine adverse effects, the length of intensive care unit (ICU) stay, complications, and mortality.

Methods

A retrospective cohort study of 152 cases collected from May 2008 to November 2012 at 2 urban university hospitals was conducted. Patients admitted to the hospital for organophosphate poisoning were divided into 2 groups with different therapeutic regimens: group A was administered a repeated pulse intramuscular injection of pralidoxime chloride, and group B received the same initial dosage of atropine and pralidoxime chloride, but pralidoxime chloride intravenous therapy was administered for only 3 days, regardless of the length of atropine therapy. Subsequently, atropine adverse effects, length of ICU stay, complications, and mortality were statistically analyzed and compared between the 2 groups.

Results

The total dose of atropine was 57.40 ± 15.14 mg in group A and 308.26 ± 139.16 mg in group B; group A received less atropine than did group B (P = .001). The length of ICU stay in group A was reduced (P = .025), and group A had fewer atropine adverse effects (P = .002). However, there was no significant difference in the mortality or complication rate between the 2 groups (P > .05).

Conclusion

In patients with severe poisoning, group A used less atropine, had fewer atropine adverse effects, and had a shorter ICU stay. We suggest that therapy should be started as early as possible using a sufficient amount of pralidoxime chloride started intramuscularly in combination with atropine and that the drugs should not be prematurely discontinued.

Introduction

Organophosphorus pesticide poisoning causes approximately 200 000 deaths each year worldwide [1]. The standard treatment of acute organophosphorus pesticide poisoning (AOPP) involves the administration of intravenous (IV) atropine and pralidoxime to counter acetylcholinesterase (AChE) inhibition at the synapse, symptomatic treatment, and supportive therapy. However, clinical trials have demonstrated the ineffectiveness of the standard therapy, with a high mortality of 43.94% [2] in Southeast Asia and India. Different organophosphates have different mortality [3]. The major causes of mortality for insecticide poisonings were the toxic effect of organophosphate, coma, and respiratory failure [4], [5].

The standard therapy for poisoning with organophosphorus pesticides requires IV atropine and oximes [6]. The role of oximes as cholinesterase agents for the treatment of organophosphorus pesticide poisoning has been further studied. However, oximes may not be useful for several theoretical and practical reasons, particularly for the late presentation of patients with dimethyl organophosphorus poisoning and in those with a large excess of organophosphorus poisoning that simply reinhibits reactivated enzymes [7]. Therefore, it is important to explore and quantify the safest and most effective method of administering oximes to patients with AOPP [8], [9], [10]. Treatment with atropine, which inhibits the effects of acetylcholine at muscarinic receptors, is well established [11], [12]. However, studies have suggested that oximes fail to benefit patients or decrease mortality [13], [14]. Therefore, many physicians prefer using only atropine to improve symptoms. Unfortunately, using a large dose of atropine has many adverse effects including increased mortality from atropine overdose.

This study aimed to determine the efficacy of 2 therapies in patients with severe AOPP and evaluated atropine adverse effects, the length of intensive care unit (ICU) stay, complications, and mortality.