[Experimental studies on dissolution of cholesterol gallstones using MTBE].

Recently, methyl tertiary butyl ether (MTBE) has been evaluated as a new cholesterol gallstone dissolving agent. The dissolution rate of cholesterol monohydrate (ChM) by MTBE was measured and effective types of MTBE administration in vivo were studied. When the dissolution rate of ChM by MTBE was compared with that of d-limonene and monooctanoin used clinically at present, MTBE was found to be the most excellent dissolving agent. However, the dissolving effect of MTBE can be suppressed by water (a component of wet gallstones and 97% of bile) because MTBE is insoluble in water. Therefore, MTBE mixed with a small amount of surfactants (MTBEP) was prepared. The dissolving effect of MTBE alone and MTBEP on dry and wet gallstones were measured. The dissolving effect of MTBE alone on the wet stones was markedly decreased, while MTBEP suppressed the decrease of dissolving effect on wet stones significantly. Furthermore, the dissolving effect of MTBE alone and MTBEP on gallstones in water were measured. MTBEP significantly improved the decrease of dissolving effect on stones by MTBE alone, because the addition of a small amount of a surfactant suppressed the influence of water for dissolving effect of MTBE. MTBE emulsion, newly type of solvent, was prepared. Although the dissolution rate of ChM in MTBE emulsion was low, the dissolving effect of MTBE emulsion was also better than that of MTBE in animal experiments. In this study, emulsion type can be expected to become excellent dissolving agents, because emulsion type suppressed the influence of water for dissolving effect of solvent.