title: Physical characterization of solid forms of urapidil.
abstract: Polymorphic forms of urapidil were prepared by various techniques. Three polymorphic forms were identified and their solid-state properties were characterized by thermal behaviour, X-ray powder diffraction, IR spectra, intrinsic dissolution rates, solution calorimetry and scanning electron microscopy. Solution calorimetry was used to determine each polymorph in mixtures of Forms I and II, with a reproducibility of +/-3%. The stability of the three polymorphic forms was followed over a period of three months under different conditions and it was concluded that Forms I, II and III of urapidil were enantiotropic.
authors.affiliation: Research Institute for Industrial Pharmacy, University of Potchefstroom for C.H.E., 2520 Potchefstroom, South Africa.
authors.forename: S A
authors.initials: SA
authors.lastname: Botha
authors.forename: J K
authors.initials: JK
authors.lastname: Guillory
authors.forename: A P
authors.initials: AP
authors.lastname: Lötter