Rheological Measurements of Compounded Emulsions and Suspensions: A Laboratory Exercise to Support Theoretical Learning

Laboratory exercises often emphasize the theoretical knowledge gained in the classroom and make concepts easier to understand. To that end, in a class of physical pharmacy (Campbell University College of Pharmacy & Health Sciences; master level graduate students), the students prepared two compounded dosage forms in order to establish their flow properties. The compounded formulations were a mineral oil emulsion and an aspirin suspension. The mineral oil emulsion was prepared by the dry gum method, while the suspension was prepared in a vehicle containing suspending agents. A Brookfield viscometer was used in the determination of the flow characteristic of the formulations. The emulsion showed a pseudoplastic flow whereas the suspension exhibited a plastic profile. During the laboratory exercise, students learned the proper use of a viscometer, how to obtain data from the viscometer using compounded dosage forms, and how to analyze the empirical results by matching them with the expected theoretical profiles. The overall informal feedback from the students on this exercise was positive.