In vitro effects of fluoride on pseudocholinesterase activity and the metabolism of the cis-trans and trans-trans isomers of mivacurium.

IN vitro experiments at room temperature with benzoylcholine as a substrate showed that 10–50 mM fluoride, the concentration usually observed with sevoflurane anesthesia, inhibits pseudocholinesterase (PChE) by 16– 56%. PChE is the enzyme responsible for the metabolism of mivacurium. Mivacurium dose requirements to maintain neuromuscular blockade are decreased by sevoflurane. In addition to the well-known potentiation of nondepolarizing neuromuscular blocking agents by volatile anesthetics, this might be caused by an inhibition of PChE. The aim of this study was to investigate whether fluoride concentrations between 10 and 1,000 mM inhibit PChE at 37°C using butyrylthiocholine and mivacurium as substrates.