Reference

Formation of dihydrate from carbamazepine anhydrate in aqueous conditions

Formation of dihydrate from carbamazepine anhydrate in aqueous conditions. Laine, Ensio; Tuominen, Virpi; Ilvessalo, Pekko; Kahela, Paavo (Dep. Phys. Sci., Univ. Turku, Turku SF-20500/50, Finland). Int. J. Pharm., 20(3), 307-14 (English) 1984. CODEN: IJPHDE. ISSN: 0378-5173. DOCUMENT TYPE: Journal CA Section: 63 (Pharmaceuticals) Section cross-reference(s): 75 Carbamazepine dihydrate (I.2H2O) [85756-57-6] crystals grow by the whisker mechanism (or mechanisms). The habit, the dimensions of the crystals and their rapid growth indicate this. Also the strong orientation in the X-ray diffractogram is in harmony with the whisker theory. The whisker growth explains also the rapid transition from the anhyd. form to the dihydrate in water. Dihydrate whiskers which are loosely in the soln. as well as ones fastened to the surface of the anhyd. mother crystal was obsd. The oriented crystal structure of I.2H2O may be at least 1 important factor in the growth mechanism of I.2H2O whiskers.

Hygroscopicity of carbamazepine crystalline powders

Hygroscopicity of carbamazepine crystalline powders. Kaneniwa, Nobuyoshi; Yamaguchi, Tetsuo; Watari, Nobutoshi; Otsuka, Makoto (Sch. Pharm. Sci., Showa Univ., Tokyo, Japan). Yakugaku Zasshi, 104(2), 184-90 (Japanese) 1984. CODEN: YKKZAJ. ISSN: 0031-6903. DOCUMENT TYPE: Journal CA Section: 63 (Pharmaceuticals) Three anhyd. forms (A, B, and C) of carbamazepine (I) [298-46-4], I.2H2O (form D) [85756-57-6] and I monoacetonate (form E) [84219-67-0] were characterized by elemental anal., IR, x-ray powder diffraction, DSC and DTA. The phase transition of these cryst. forms was investigated. Form A, obtained by recrystn. from EtOH, and form C, obtained by drying at 115°, were very stable to moisture. Form B was relatively hygroscopic and when stored under 100% relative humidity (RH) for 3 days, was transformed into form D by absorbing 2 mol of H2O. Form D was stable to moisture when stored under 40-91% RH at 37°, but when stored under 32% RH for 2 wk, it lost 2 mol H2O and was transformed into form C. Form E obtained by recrystn. from Me2CO and stored under 100% RH for 2 wk, absorbed 2 mol H2O and was transformed into form D.In this experiment, several chemicals are used like 298-46-4 and 85756-57-6 Transition temp., heat of transition, desolvation temp., and heat of desolvation were measured by DSC and DTA. .