Quantitative assay of physostigmine in human whole blood

A quantitative assay for measuring physostigmine in human whole blood is described. Blood samples are maintained at 37 degrees, and cholinesterase activity is measured periodically. The time required for enzyme reactivation is related to physostigmine concentration. The precision of the method is within +/- 4% over a physostigmine concentration range of 0.5-5.0 x 10(-7) M.