Processing and storage effects on water vapor sorption by some model pharmaceutical solid dosage formulations

Several excipients and their formulations were equilibrated at relative humidities and temperatures selected to simulate typical pharmaceutical storage and processing conditions. Three different water detection techniques-loss on drying, Karl Fischer coulometry and an automatic moisture balance, were used to determine the moisture content of these systems. The excipients all possessed very different water sorption tendencies, as did their formulations. Isothermal water sorption by the dry blends, granules and tablets of each formulation was identical, suggesting that the processes involved in tablet manufacturing did not affect the water sorption behavior. Accurate water content predictions for the formulations were possible by adding the contribution of water from each excipient. Such predictions may be helpful for defining upper and lower water content specifications and storage conditions for excipients and their formulations. (C) 1997 Elsevier Science B.V.