Physical characterization of solid forms of urapidil.
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.
Botha
S A
SA
Research Institute for Industrial Pharmacy, University of Potchefstroom for C.H.E., 2520 Potchefstroom, South Africa.
Guillory
J K
JK
Lötter
A P
AP