Solubility and prediction of the heat of solution of sodium naproxen in aqueous solutions

✍ Scribed by Young-soo Kim; José R. Méndez del Río; Ronald W. Rousseau

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 178 KB
• Volume: 94
• Category: Article
• ISSN: 0022-3549
• DOI: 10.1002/jps.20391

✦ Synopsis

The solubility of sodium naproxen was determined over a range of temperatures from 15.28C to 39.78C by two methods: analyses of samples from equilibrated solutions and a recently developed procedure utilizing a focused-beam reflectance method (FBRM). The results demonstrate the utility of the newer and, in some cases, simpler method. A discontinuity in the solubility was observed at 29.88C, identifying the temperature as which the dihydrate and anhydrous forms of sodium naproxen trade places as being the more stable of the two forms. The heats of solution for the two pseudopolymorphs were obtained from van't Hoff plots of the solubility data. These results were used to demonstrate how the heat of solution of one form can be estimated using the heat of dehydration obtained from differential scanning calorimetry (DSC) and the heat of solution from another form.