Graham_1995_Eur.J.Clin.Pharmacol_48_225

The inhibition of serum cholinesterase by metoclopramide has been previously characterised in vitro at high dilution of the enzyme. We examined the effect of varying enzyme dilution over a range of 1000 fold dilution, and assay temperature at 25 degrees C and 37 degrees C on the fractional inhibition of enzyme activity by metoclopramide. Neither enzyme concentration nor reaction temperature affected this fractional inhibition. Concentrations of metoclopramide producing 50% inhibition of enzyme activity were in the range 1.0-1.9 x 10(-6) M. Lineweaver-Burk analysis of the enzyme reaction suggests that the pattern of this inhibition is competitive.