| 摘要 |
PURPOSE: To provide an amorphous piretanide having a solubility in an acidic and especially neutral aqueous solution higher than that of conventional piretanide crystal. CONSTITUTION: This amorphous piretanide exhibits exothermic peaks at about 136 deg.C and about 209 deg.C, an endothermic peak at about 207 deg.C and a melting peak at about 225 deg.C by differential thermal analysis, a halo pattern free from 28 diffraction peak by powder X-ray diffraction and characteristic peaks at about 1700cm<-1> and 3200-3500cm<-1> in infrared absorption spectrum. The amorphous piretanide can be produced by dissolving a piretanide in a basic aqueous solution, adding water to the solution to adjust the pH of the solution to >3.87 and <=4.37 and collecting the produced precipitate. The solubility of the amorphous piretanide (37 deg.C) in a buffer solution of pH 1 is 2 times the solubility of a type-A piretanide recrystallized from a methanol aqueous solution and 1.2 times the solubility of the type-B piretanide obtained by heating a crystal solvated with organic solvent. It is suitable as an agent for oral administration or injection. |
