By Dr. Robin Bogner, University of Connecticut
Product resistance (Rp) is the resistance to vapor flow through the dried layer out of the vial during primary drying. Along with the vial heat transfer coefficient (Kv), product resistance is a key determinant of the product temperature. It can provide instantaneous structural information about cake morphology at the point of measurement. However, characterizing Rp remains the weakest part of any predictive model of primary drying.
Recently, Dr Robin Bogner from the University of Connecticut, USA presented a webinar that discussed the factors that influence product resistance and ways to measure it during primary drying of the lyophilization cycle for products in vials. This article summarizes the webinar and includes a selection of questions from the Q&A session.