Introduction: At present, there are numerous researches on the migration of components
in tablets and granules, however, the investigation in the pharmaceutical literatures concerning
the effect of drying rate on the migration of water-soluble components of pellets is limited.
Temperature and Relative Humidity (RH) are crucial parameters during the drying process, which
is an essential step in the preparation of pellets via wet extrusion/spheronization. To quantify these
variables, the water loss percentage of pellets per minute is defined as the drying rate.
Aim: The study aimed to investigate the influence of drying rate on the migration of water-soluble
components in wet pellets and the potential migrated mechanism.
Methods: The pellets containing tartrazine as a water-soluble model drug and microcrystalline cellulose
as a matrix former were prepared by extrusion/spheronization and dried at four different drying
temperatures and relative humidity. Afterwards, the extent of migrated tartrazine was assessed
regarding appearance, in-vitro dissolution test, Differential Scanning Calorimetry, X-Ray Powder
Diffraction, Attenuated total reflectance Fourier transform infrared spectroscopy and Confocal Raman
Results: Results demonstrated that red spots of tartrazine appeared on the surface of pellets and
more than 40% tartrazine were burst released within 5 minutes when pellets were dried at 60°C/RH
10%. When pellets were dried at 40°C/RH 80%, none of these aforementioned phenomena were observed.
Conclusion: In conclusion, the faster the drying rate was, the more tartrazine migrated to the exterior
of pellets. Adjusting drying temperature and relative humidity appropriately could inhibit the migration
of water-soluble components within wet extrusion/spheronization pellets.