盐对酸性药物溶度和分配系数的影响

The Effect of Salts on the Distribution and Solubility of Acidic Drugs

用分光光度法测定和计算药物在不同实验体系中的活度系数、盐析常数和分配系数。结果表明,氯化钠、氯化钾产生盐析作用使扑热息痛、水杨酸溶度减小并使扑热息痛在正辛醇——水系统中分配系数增大,但氯化钠使水杨酸的分配系数减小,其原因除水相盐析作用外,必须考虑其它因素如pKa,pH等的影响。

The distribution coefficient and the solubility of paracetamol and salicylic acid were determined spectrophotometrically as a function of added sodium chloride and potassium chloride. The activity coefficient and salting—out constants have also been calculated. It was found that sodium chloride and patassium chloride decreased the solubility of paracetamol and salicylic acid and increased the distribution coefficient of paracetamol at experimental concentrations of salts. The decrease in solubility and the increase in distribution coefficient were shown to be due to the salting—out effect. However, the distribution coefficient of salicylic acid in presence of sodium chloride was decreased at the same condition. The reason for this is probably affected by other factors for example pKa of salicylic acid and pH of the aqueous phase and so on.