[A new direct solubilizer for bilirubinate calcium stones].

Hepatobiliary surgeons must have faced difficulty in treating patients with intrahepatic gallstones. In spite of considerable progress in operative methods or mechanical techniques, it is very difficult to remove intrahepatic gallstones completely. Under such circumstances, the development of a solubilizer that can dissolve intrahepatic bilirubinate calcium stones by means of injecting it through a postoperative catheter or PTCD catheter has been awaited. Up to now, a chelating agent, so-called hexametaphosphate (HMP) has been used for removing the calcium from calcium bilirubinate. But this chelating agent, in itself, cannot dissolve the bilirubin. The authors found a direct solubilizer for bilirubin, dimethyl sulfoxide (DMSO) which is a well known bi-polar non protonic solvent and used as an accelerator for bilirubin determination. After the purification of DMSO to 99.98%, toxicity was examined by oral administration, intravenous administration and infusion into biliary tract. But no remarkable toxicity or side effects were detected on biochemical and pathological examinations. Clinical application of 90% DMSO together with 5% HMP was performed and a satisfactory effect was obtained as a direct solubilizer for bilirubinate calcium stones.