Phenobarbital treatment in primary biliary cirrhosis. Differences in bile acid composition between responders and nonresponders.

We have studied the effect of phenobarbital treatment on total serum bile acid levels and serum bile acid composition in five patients with primary biliary cirrhosis and one patient with sclerosing cholangitis. These patients were divided into two groups according to their apparent response to phenobarbital treatment. One group, consisting of three patients with primary biliary cirrhosis and the patient with sclerosing cholangitis, demonstrated very high initial total serum bile acid levels, which decreased substantially during phenobarbital therapy. There sera had no secondary bile acids, and a decrease in the trihydroy/dihydroxy ratio occurred during phenobarbital therapy. The second group consisted of two primary biliary cirrhosis patients who showed no reduction of bile acids during treatment. Their initial total serum bile acid levels were lower than those in the first group and paradoxically showed a slight increase with phenobarbital therapy. The fact that no significant amounts of unusual bile acids were detected in either group indicates that abnormal pathways of bile acid metabolism were not present and that in all likelihood, phenobarbital did not alter the conventional pathways of bile acid biosynthesis in these five patients.