Investigating carbamazepine-acetone solvate formation via dynamic gravimetric vapor sorption

Pharmaceutical solids can often form solvated species which can affect the material's physical and chemical stability. Carbamazepine (CBZ) has been proven to form a 1:1 solvate with acetone. This report investigates the solvation behavior of CBZ over a wide temperature and acetone concentration range using Dynamic gravimetric Vapor Sorption (DVS). The solvation transition point increased from 62.5% P/P (0) at 10 degrees C to 97.8% P/P (0) at 30 degrees C, resulting in a 15.9 kJ mol(-1) heat of solvation. The desolvation kinetics were studied between 15 and 30 degrees C, indicating CBZ desolvation is a first-order reaction with autocatalysis by the desolvated product and an activation energy of 81.9 kJ mol(-1).