Drugs as probes of organ function: evaluation of the hepatobiliary axis using oral rifampicin and novel high performance liquid chromatography.

Investigation of the uptake and metabolism of drugs by organs such as the liver may allow assessment of specific aspects of organ function. Rifampicin, when orally administered, is transported into the hepatocyte from portal blood and thence passes, with its deacetylated metabolite, into the systemic circulation and into bile. This paper reports an investigation of the pharmacokinetics of a sub-therapeutic oral dose of rifampicin in healthy subjects, in patients with cirrhosis and in subjects with Gilbert's syndrome. The areas under the plasma concentration curves (AUC) in patients with cirrhosis were significantly greater than in healthy subjects. Subjects with Gilbert's syndrome had decreased AUCs compared with healthy subjects and were clearly distinguished from patients with cirrhosis. Rifampicin concentration in serum was measured by HPLC using a novel direct injection technique.