The temporal profile of
butyrylcholinesterase (BuChE) and in vitro
pralidoxime-reactivated BuChE was studied in a cohort of 25
organophosphate-poisoned patients to examine their relationship to the development of intermediate syndrome and to understand reasons for lack of efficacy of
oxime treatment. The clinical severity of
poisoning (assessed by the Namba Scale) correlated significantly with the severity of intermediate syndrome. BuChE activity increased significantly over time and showed significant relationship to muscle power. The temporal profile of the
enzyme was correlated to the clinical severity of
poisoning. Reactivation potentials of BuChE (the difference between
oxime-reactivated and -unreactivated
enzyme activity) declined significantly with time after
organophosphate ingestion. The reactivation potential of the
enzyme at admission decreased significantly with increasing severity of
poisoning and was lower in patients who developed intermediate syndrome. Patients who received
oxime prior to hospitalization had a higher rate of intermediate syndrome and lower levels of BuChE at admission than those who had not. The study suggests that (i) BuChE reflects the
clinical course of
poisoning, confirming earlier studies; (ii) intermediate syndrome may be associated with a persistent inhibition of BuChE; and (iii) the lack of
oxime efficacy in our patients maybe due to their severity of
poisoning and the timing of
oxime treatment.