title: Pseudopolymorphism and phase stability in four solid forms of (6R,7R)-7-[2-(5-amino-1,2,4-thiadiazol-3-yl)-(Z)-2-methoxy- iminoacetamid]-3- [(4-carbamoyl-1-quinuclidinio)methyl]-8-oxo-5-thia-1-azabicyclo - [4,2,0]oct-2-ene-2-carboxylate (E1040).
abstract: (6R,7R)-7-[2-(5-Amino-1,2,4-thiadiazol-3-yl)-(Z)-2-methoxy- iminoacetamid]-3- [(4-carbamoyl-1-quinuclidinio)methyl]-8-oxo-5-thia-1-azabicyclo [4,2,0]oct-2-ene-2-carboxylate (1; E1040) was isolated as alpha-(decahydrate), beta-(pentahydrate), and gamma-form (anhydrate) crystals and the X-ray amorphous form. The relationship between the pseudopolymorphic crystal forms of this compound and water content was studied by X-ray diffractometry, coulometric moisture analysis, thermal analysis, and hygroscopic and vacuum-freeze-drying experiments. The phase transition of crystalline 1 clearly indicated the effect of water content on dehydration. During dehydration, hydrated alpha-form (decahydrate) crystals and beta-form (pentahydrate) crystals became anhydrate gamma-form crystals, with the diffraction angle shifting toward shorter spacing accompanied by line broadening. These results indicate conversion of hydrate 1 crystals to the anhydrous form and contraction of the crystal lattice. It was estimated that the decahydrate (alpha-form) crystals contain 8 mol/mol crystal water and 2 mol/mol adhesion water, and that the pentahydrate (beta-form) crystals contain 4 mol/mol crystal water and 1 mol/mol adhesion water. These estimates were made by comparing the data from equilibrium hydration experiments and vacuum-freeze-drying experiments. It thus follows that gamma-form crystals are anhydrate and the X-ray amorphous form exists in either the hydrous or anhydrous form.
authors.affiliation: Department of Physical Chemistry, Eisai Company, Ltd., Ibaraki, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ashizawa
authors.forename: K
authors.initials: K
authors.lastname: Uchikawa
authors.forename: T
authors.initials: T
authors.lastname: Hattori
authors.forename: Y
authors.initials: Y
authors.lastname: Ishibashi
authors.forename: T
authors.initials: T
authors.lastname: Sato
authors.forename: Y
authors.initials: Y
authors.lastname: Miyake
mesh_terms: D000268:Adhesiveness; D002511:Cephalosporins / Q000032:analysis*; D055598:Chemical Phenomena; D002621:Chemistry; D003460:Crystallization; D004355:Drug Stability; D004356:Drug Storage; D005612:Freeze Drying; D006813:Humidity; D007536:Isomerism; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D002511:Cephalosporins; C056494:cefclidin