title: Preparation and physicochemical characterization of 5 niclosamide solvates and 1 hemisolvate.
abstract: The purpose of the study was to characterize the physicochemical, structural, and spectral properties of the 1:1 niclosamide and methanol, diethyl ether, dimethyl sulfoxide, N,N' dimethylformamide, and tetrahydrofuran solvates and the 2:1 niclosamide and tetraethylene glycol hemisolvate prepared by recrystallization from these organic solvents. Structural, spectral, and thermal analysis results confirmed the presence of the solvents and differences in the structural properties of these solvates. In addition, differences in the activation energy of desolvation, batch solution calorimetry, and the aqueous solubility at 25 degrees C, 24 hours, showed the stability of the solvates to be in the order: anhydrate > diethyl ether solvate > tetraethylene glycol hemisolvate > methanol solvate > dimethyl sulfoxide solvate > N,N' dimethylformamide solvate. The intrinsic and powder dissolution rates of the solvates were in the order: anhydrate > diethyl ether solvate > tetraethylene glycol hemisolvate > N,N' dimethylformamide solvate > methanol solvate > dimethyl sulfoxide solvate. Although these nonaqueous solvates had higher solubility and dissolution rates than the monohydrous forms, they were unstable in aqueous media and rapidly transformed to one of the monohydrous forms.
authors.affiliation: Research Institute for Industrial Pharmacy, Potchefstroom University for CHE, Potchefstroom 2520, South Africa.
authors.forename: Elsa C
authors.initials: EC
authors.lastname: van Tonder
authors.forename: Mabatane D
authors.initials: MD
authors.lastname: Mahlatji
authors.forename: Sarel F
authors.initials: SF
authors.lastname: Malan
authors.forename: Wilna
authors.initials: W
authors.lastname: Liebenberg
authors.forename: Mino R
authors.initials: MR
authors.lastname: Caira
authors.forename: Mingna
authors.initials: M
authors.lastname: Song
authors.forename: Melgardt M
authors.initials: MM
authors.lastname: de Villiers
mesh_terms: D055598:Chemical Phenomena; D002626:Chemistry, Pharmaceutical; D002627:Chemistry, Physical; D009534:Niclosamide / Q000737:chemistry*; D011208:Powders / Q000737:chemistry*; D012995:Solubility; D012997:Solvents / Q000737:chemistry; D013057:Spectrum Analysis; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D011208:Powders; D012997:Solvents; D014867:Water; D009534:Niclosamide