ADDITION OF DIMETHYLSULFOXIDE TO METHYL-TERT-BUTYL ETHER AND ETHYL PROPIONATE INCREASES CHOLESTEROL DISSOLVING CAPACITY AND CHOLESTEROL GALL STONE DISSOLUTION IN-VITRO

There is a discrepancy between in vitro cholesterol dissolving efficac y of methyl-tert-butyl ether (MTBE) and ethyl propionate and cholester ol gall stone dissolution in vivo. This study investigated whether the presence of bile changes the cholesterol dissolving capacity of MTBE and ethyl propionate. The addition of dimethylsulphoxide to MTBE or et hyl propionate was also studied to discover if it improves the dissolv ing capacity for cholesterol gall stones. The presence of bile caused a 25% decrease in cholesterol dissolving capacity of both MTBE and eth yl propionate (p<0.0001). This inhibitory effect of bile could be over come by the addition of dimethylsulphoxide: dimethylsulphoxide caused an increase in cholesterol dissolving capacity of MTBE and ethyl propi onate, the increase depending on the dimethylsulphoxide/bile ratio in the mixture. Mean dissolution time of weight, size, and patient matche d cholesterol gall stones was 220 minutes in MTBE and 130 minutes in M TBE/dimethylsulphoxide (p<0.0001). No stones dissolved completely in e thyl propionate or ethyl propionate/dimethylsulphoxide within 300 minu tes. In conclusion, MTBE/dimethylsulphoxide is a more potent dissolvin g agent for cholesterol gall stones than MTBE, giving a 40% reduction in dissolution time. Addition of dimethylsulphoxide to ethyl propionat e does not result in faster stone dissolution. MTBE and MTBE/dimethyls ulphoxide are far superior to ethyl propionate as solvents for cholest erol gall stones.