title: Effect of environmental humidity on the transformation pathway of nitrofurantoin modifications during grinding and the physicochemical properties of ground products.
abstract: The effect of humidity on the physicochemical properties of nitrofurantoin anhydrate and monohydrate during grinding in a humidity-controlled system was investigated using X-ray diffraction analysis, IR spectroscopy, thermal analysis and scanning electron microscopy. Anhydrate and monohydrate were transformed into a noncrystalline solid and a stable monohydrate, respectively, during grinding in a closed system. During grinding in an open system, in which the humidity level of the air was controlled (5, 50 and 75% r.h.), the anhydrate absorbed moisture from the supplied air and water content was increased at 75% r.h.; thereafter the compound was transformed into monohydrate II. The anhydrate did not absorb at 5 or 50% r.h. and was transformed into a noncrystalline solid. Monohydrate I desorbed crystal water during grinding at 5% r.h. and was transformed into a noncrystalline solid. However, monohydrate I was transformed into monohydrate II at 50 and 75% r.h. without desorption of crystal water. These results suggest that the solid-state transformation of nitrofurantoin during grinding depends upon the environmental humidity.
authors.affiliation: Department of Pharmaceutical Technology, Kobe Women's College of Pharmacy, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Otsuka
authors.forename: Y
authors.initials: Y
authors.lastname: Matsuda
mesh_terms: D000812:Anhydrides / Q000737:chemistry; D055598:Chemical Phenomena; D002626:Chemistry, Pharmaceutical / Q000379:methods; D002627:Chemistry, Physical; D004355:Drug Stability; D006813:Humidity; D009582:Nitrofurantoin / Q000737:chemistry*; D010316:Particle Size; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D000812:Anhydrides; D009582:Nitrofurantoin