Preformulation investigation of the novel proton pump inhibitor lansoprazole.

Some technologically important physicochemical properties of lansoprazole were investigated. This compound is very unstable, especially in aqueous solutions with low pH. It has one acidic and two basic dissociation constants. Lansoprazole has relatively high solubility in solutions with high pH and is well partitioned from aqueous to n-octanol phase. Under conditions examined in this study, lansoprazole was not hydroscopic and did not decompose at higher relative humidities.