Abstract
The following results were obtained on the dissolution of sulfadiazine in various aqueous solution. 1. On the dissolution in sucrose solution, with an increase of sucrose concentration, the saturated concentration, CO was increased a little, and the dissolution constant, KT, was decreased with an increase of viscosity following an increase of the concentration. The dissolution rate by practical representation, KT×CO, became smaller with an increase of sucrose concentration. The dissolution was in accordance with the Noyes-Nernst model, and CO was coincident with the solubility, CS.2. On the dissolution in sodium chloride solution, both KT and CO were decreased with an increase of the concentration of sodium chloride. The dissolution was in accordance with the Noyes-Nernst model.3. On the dissolution in sodium hydroxide solution, both KT and CO were increased with an increase of the concentration of sodium hydroxide. The dissolution was in accordance with the Nernst-Brunner model. The increase of KT was considered to be due to the increase of diffusion coefficient of sodium hydroxide in the presence of sodium salt of sulfadiazine. 4. The dissolution in Na2HPO4 solution, in Mc'Ilvaine buffer solution and in hydrochloric acid solution were in accordance with the Higuchi model, and as an increase of concentration of the solution, CO was increased by the change of hydrogen ion concentration. 5. The dissolution in urea solution did not fit to any of the model in Table I.
