The effect of liver disease and food on plasma MEGX concentrations.

Plasma monoethylglycinexylidide (MEGX) concentrations were measured in 15 healthy controls (age 23-46 years) and 12 patients with biopsy proven cirrhosis (age 34-70 years) 30 min after 1 mg kg-1 intravenous lignocaine. Mean (+/- s.d.) MEGX concentrations were 57 +/- 33 ng ml-1 in the controls compared with 21 +/- 18 ng ml-1 in the cirrhotics (P < 0.05), but there was overlap in the range of concentrations. MEGX concentrations were inversely correlated with age, but not disease severity, in the cirrhotic patients (r = 0.62, P = 0.04) but not in the control subjects. In a second study 20 healthy subjects were given 1 mg kg-1 intravenous lignocaine on two occasions; either fed or fasted, and samples taken at 15, 30 and 60 min after dosage. MEGX concentrations were not significantly different at any time within either day or between fed and fasted study days. There was no correlation with age. The plasma lignocaine concentration at 15 min was significantly higher fed than fasted (2.88 +/- 2.44 and 1.82 +/- 0.96 micrograms ml-1, P = 0.01). Measurement of plasma MEGX after i.v. lignocaine is a useful test of liver function and may be performed in fed or fasted subjects. It is reproducible within an individual but is not specific for cirrhosis and appears age-related in liver disease.