THE LOW-DOSE MONOETHYLGLYCINEXYLIDIDE TEST - ASSESSMENT OF LIVER-FUNCTION WITH FEWER SIDE-EFFECTS

The hepatic metabolism of lidocaine (1 mg/kg intravenously) to its met abolite monoethylglycinexylidide (MEG-X) is the basis of the standard MEG-X test, To reduce the lidocaine-induced side effects, we evaluated the MEG-X formation after 0.5 and 1 mg/kg lidocaine intravenously in subjects with normal (n = 5) and severely impaired liver function (n = 7) (study I), From this study, a low-dose test (MEG-X concentration 3 0 minutes after 50 mg Lidocaine intravenously [MEG-X-30min] normalized to standard MEG-X test results) was developed, Sensory side effects f rom this low dose and from the standard MEG-X test were compared in a double-blind, randomized, cross-over study (study II) comprising 15 in dividuals with normal liver function and 45 patients with cirrhosis (1 5 Child A, 15 Child B, and 15 Child C). In study I, MEG-X formation ra te was dose-independent in patients with severely impaired liver funct ion, In study II, normalized MEG-X test results (ranging from less tha n or equal to 4 to 120 mu g/L) were virtually identical to the standar d test results (mean difference: -1.9 mu g/L; 95% confidence interval [CI]: -5.3; 1.5 mu g/L), Fewer individuals experienced side effects (3 0% vs, 53%) with the low dose test (P = .0013), In a multivariate anal ysis, the Child-Pugh score was inversely related to the occurrence of side effects. The low-dose MEG-X test gives almost identical results t o the standard MEG-X test and is associated with fewer side effects, w hich occur less often in individuals with more severely compromised li ver function.