Viscosity of Amorphous Solid Dispersions at Humid Conditions

used as medical tablets. If the concentration of the API exceeds its equilibrium solubility in the polymer, it tends to crystallize.
This should be avoided during the shelf life of the ASD as it decreases the bioavailability of the API in the human body.
One factor influencing the ASD shelf life is the molecular mobility of the API in the polymer. Since these molecular motions
are physically related to viscosity, the molecular mobility can be evaluated based on viscosity. We proposed an approach to
predict the viscosity of ASDs only based on the temperature dependence of the viscosity of the neat polymer as well as the
predicted water content in the ASD at certain relative humidity (RH) using the Perturbed-Chain Statistical Associating Fluid
Theory (PC-SAFT). This approach helps to remarkably reduce the experimental effort for identifying suitable polymers to
be used in ASDs.

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