Plasmapheresis and plasma cholinesterase.

Plasma cholinesterase (E.C. 3.1.1.8) concentrations were measured in nine outpatients who were undergoing regular plasmapheresis. A single plasmapheresis produced a 64% reduction in cholinesterase concentration compared with the value before plasmaphersis. Another patient who received four plasma exchanges in 6 days showed a progressive reduction in cholinesterase concentration to only 8% of the initial value. It is suggested that drugs metabolized by cholinesterase should be used with caution in patients undergoing plasmapheresis, particularly when frequent plasma exchanges are undertaken.