Comparative In Vitro Studies of Dimethadione and Citric Acid for Lysis of Pancreatic Stones.

Abstract

It is generally accepted that the main constituent of pancreatic stones is calcium carbonate (CaCO3). In order to detect the mechanism of dissolution of pancreatic stones by two types of organic acid, dimethadione (DMO) and citric acid, comparative in vitro experiments were performed by using the chemical agent of CaCO3. Bicarbonate aqueous solution, nonboiled and boiled canine pancreatic juice (bicarbonate concentration: 0 to 104 mmol/L) were used as the solvent for the organic acid. Concentration of organic acid was adjusted to 0, 0.77, 1.54, 3.08, 6.16, and 7.70 mmol/L. The amount of 0.2g CaCO3 was added in the powder form to respective 100 ml solutions, which were then filtered at the appropriate interval up to 120 min. Calcium concentration in the filtrate reached the plateau (i. e. the saturated concentration) about 5 min after adding CaCO3 to the solution. The solubility of CaCO3, when expressed as a logarithmic scale of the saturated calcium concentration, correlated positively with the concentration of the organic acid, and negatively to both the bicarbonate concentration and pH. In addition, the solubility of CaCo3 was higher in citric acid solution than in DMO solution, and was suppressed in nonboiled pancreatic juice. These results suggest that the solubility of CaCO3 can be regulated by two major factors; dissociation of protons from these organic acids, and buffer action of bicarbonate ion or pancreatic protein on protons.