Theophylline pharmacokinetics in patients with liver diseases with reference to estimated hepatic blood flow

Pharmacokinetics of theophylline were determined in patients with liver cirrhosis and idiopathic portal hypertension with reference to estimated hepatic blood flow assessed by indocyanine green (ICG). Decreased plasma clearance of theophylline was noted in patients with liver cirrhosis and the clearance was significantly lower in Child C group than in Child A, B groups (17.5 +/- 3.4 ml/Kg/hr vs 27.6 +/- 8.7, p less than 0.05). Theophylline has been classified as a drug with a low hepatic extraction ratio and it has been believed that changes in hepatic blood flow have little effect on its clearance. The results of present study indicate that theophylline clearance is basically not related to ICG clearance but to theophylline extraction ratio, supporting the common belief. However, it is noteworthy that the clearance was related to decreased hepatic blood flow rather than extraction ratio in a cirrhotic patient with huge extrahepatic shunt, suggesting that hepatic clearance of this drug could be affected by hepatic blood flow under some circumstances.