Assessment of hepatic function in cystic fibrosis by lidocaine metabolism

Background: To determine hepatic drug metabolism in patients with cystic fi brosis, as measured by monoethylglycinexylidide formation after lidocaine i njection and indocyanine green (ICG) clearance. Methods: The following study is a case-control study, which included 19 pat ients with cystic fibrosis and 13 control subjects. Serum monoethylglycinex ylidide concentration was measured after intravenous injection of 1 mg/kg ( maximum, 50 mg) lidocaine. Indocyanine green (0.5 mg/kg) was injected conco mitantly, and absorbance (805 nm) of serum was measured over time to determ ine its volume of distribution, serum half-life, and hepatic blood flow. Results: Monoethylglycinexylidide formation was decreased in patients with cystic fibrosis compared with controls (39.4 +/- 16.9 mug/L versus 70.3 +/- 45.7 mug/L, mean +/- SD, respectively, P < 0.02). Indocyanine green half-l ife (4.6 +/- 2.7 min versus 3.0 +/- 1.0 min), volume of distribution (8.6 /- 5.5 L versus 8.3 +/- 3.4 L), and hepatic blood flow (10.9 +/- 5.9 ml kg( -1) min(-1) versus 7.4 +/- 2.0 ml (.) kg(-1 .) min(-1)) were similar in bot h groups. Conclusion: Monoethylglyeinexylidide formation after lidocaine injection is impaired in patients with cystic fibrosis. This impairment may have clinic al implications when using hepatically metabolized medications in patients with cystic fibrosis. (C) 2001 Lippincott Williams & Wilkins, Inc.