Abstract
Objective. The effects of obidoxime in the treatment of organophosphate poisoning were assessed by biochemical and biological effect monitoring. In this article we report effects on neuromuscular function, oxime and atropine concentration, and relate them to acetylcholinesterase (AChE) activity. Methods. We measured the activity of cholinesterase in plasma and AChE in red blood cells (RBC) and related these data with neuromuscular transmission analysis (ulnar nerve stimulation). Concomitantly, poison and oxon along with plasma obidoxime and atropine levels were measured at regular intervals. Results. We found a close correlation between RBC–AChE activity and neuromuscular transmission and a reciprocal correlation between both the atropine maintenance dose and/or its plasma concentration. The steady state of RBC–AChE activity of reactivation and re-inhibition followed the course predicted by laboratory-determined reaction constants. Conclusions. Intense monitoring of organophosphate-poisoned patients allowed assessment of why a given obidoxime concentration was, or was not, able to counteract the re-inhibition of the RBC–AChE. RBC–AChE activity mirrors the function of n-receptor- and m-receptor-mediated cholinergic signaling as measured by neuromuscular transmission and atropine requirements.
Acknowledgments
The authors thank the ICU staff of the study hospitals for their support; Dr. Michael Haberkorn for his help with neurophysiological examinations; and Christine Diepold, Renate Heilmair, Maria Radtke, and Elisabeth Topoll for technical assistance.
Conflict of interest statement: The study was funded by a Contract-Research-Project (0597-V-4800) for the Bundeswehr Medical Service. The authors have no potentially conflicting financial or institutional interests with the submitted manuscript.