Kinetics of transition of anhydrous carbamazepine to carbamazepine dihydrate in aqueous suspensions.
When suspended in water, anhydrous carbamazepine (C15H12N2O; 1) was transformed to carbamazepine dihydrate (C15H12N2O.2H2O; 2). Compound 1 was dispersed in water at 25 degrees C, and an aliquot of the slurry was taken at periodic intervals and immediately filtered under conditions which removed all the physically bound water from the solid. The weight fractions of 1 and 2 in the solid were quantified by two methods: (a) by determining the weight loss on drying the solid at 60 degrees C under reduced pressure to a constant weight and (b) by a quantitative powder X-ray diffraction technique. There was good agreement between the above two methods. More than 95% (w/w) of 1 was converted to 2 in 1 h and the decrease in the weight fraction of 1 with time was approximately a first-order process.
Young
W W
WW
Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis 55455.
Suryanarayanan
R
R
D002220:Carbamazepine / Q000737:chemistry*; D011208:Powders; D013535:Suspensions; D014961:X-Ray Diffraction
D011208:Powders; D013535:Suspensions; D002220:Carbamazepine