Abstract
A stationary disk method for dissolution rate measurement in aqueous solution was improved and simplified. Also its application to solubility determination has been attempted for substances such as salicylic acid and benzoic acid, and satisfactory results were obtained in rather short time. Polyvinylchloride (PVC) powder was used as an inert solid “binder, ” and was mixed with sample powder to form into disks, if a substance cannot be prepared into the compressed disk in pure powder form. No effect of PVC on solubility determination was observed. Also, results obtained by application of the method to sulfathiazole polymorphic forms were discussed, and their solubilities were determined to be 479.2 mg/liter and 819.2 mg/liter for the stable form and the metastable form, respectively.
