A color-reaction-based rapid screening for null activity of butyrylcholinesterase: a step toward point-of-care screening for succinylcholine apnea.

Succinylcholine apnea happens in cases of null butyrylcholinesterase activity after administration of preintubation succinylcholine. So far, there is no such popular test that can rapidly screen null butyrylcholinesterase activity from plasma. Development of a novel method for rapid screening of null butyrylcholinesterase activity of plasma samples was the objective of the current work. Dichromate reagent was added to 1-naphthol, 2-naphthol, phenol, and para-nitrophenol in separate aliquots and watched for the color formation. Plasma samples preincubated with and without selective butyrylcholinesterase inhibitor were mixed with 1-naphthylacetate and watched for color development after addition of dichromate reagent. Fitting of 1-naphthylacetate at the active site of butyrylcholinesterase was analyzed by using tools of computational biology. It was seen that 1-naphthol formed color with dichromate reagent in a concentration-dependent manner. Other phenols did not form color with dichromate reagent even at 500-µm concentrations. Plasma sample with and without selective butyrylcholinesterase inhibitor (tetra isopropyl pyrophosphoramide) was distinguishable by color formation when incubated with 1-naphthylacetate, followed by the addition of dichromate reagent. In silico analysis also showed that 1-naphthylacetate fitted well at the active site of butyrylcholinesterase. The developed method may be used for rapid screening for null butyrylcholinesterase activity at point of care.