title: Physical characterization of the hydrates of urapidil.
abstract: Three hydrates of urapidil were prepared and characterized by means of differential scanning calorimetry, thermogravimetric analysis, infrared spectroscopy, X-ray powder diffraction, intrinsic dissolution rates, and solution calorimetry. The stoichiometry of the urapidil hydrates was found to be 1:5, 1:3, and 1:1 (urapidil:water). The crystal and molecular structures of urapidil pentahydrate were determined from three-dimensional X-ray data. The stability of the pentahydrate and monohydrate under different storage conditions was also determined.
authors.affiliation: Research Institute for Industrial Pharmacy, University of Potchefstroom for C.H.E., South Africa.
authors.forename: S A
authors.initials: SA
authors.lastname: Botha
authors.forename: M R
authors.initials: MR
authors.lastname: Caira
authors.forename: J K
authors.initials: JK
authors.lastname: Guillory
authors.forename: A P
authors.initials: AP
authors.lastname: Lötter
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003461:Crystallography; D004055:Differential Thermal Analysis; D004355:Drug Stability; D008855:Microscopy, Electron, Scanning; D010879:Piperazines / Q000032:analysis*; D012995:Solubility; D013055:Spectrophotometry, Infrared; D013237:Stereoisomerism; D014961:X-Ray Diffraction
chemical_list: D010879:Piperazines; C015568:urapidil