title: Colorful drying.
abstract: Drying is one of the standard unit operations in the pharmaceutical industry and it is important to become aware of the circumstances that dominate during the process. The purpose of this study was to test microcapsulated thermochromic pigments as heat indicators in a fluid bed drying process. The indicator powders were manually granulated with alpha-lactose monohydrate resulting in three particle-size groups. Also, pellets were coated with the indicator powders. The granules and pellets were fluidized in fluid bed dryer to observe the progress of the heat flow in the material and to study the heat indicator properties of the indicator materials. A tristimulus colorimeter was used to measure CIELAB color values. Color indicator for heat detection can be utilized to test if the heat-sensitive API would go through physical changes during the pharmaceutical drying process. Both the prepared granules and pellets can be used as heat indicator in fluid bed drying process. The colored heat indicators give an opportunity to learn new aspects of the process at real time and could be exploded, for example, for scaling-up studies.
authors.affiliation: Division of Pharmaceutical Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, 00014 Helsinki, Finland. satu.lakio@helsinki.fi
authors.forename: Satu
authors.initials: S
authors.lastname: Lakio
authors.forename: Jyrki
authors.initials: J
authors.lastname: Heinämäki
authors.forename: Jouko
authors.initials: J
authors.lastname: Yliruusi
mesh_terms: D003116:Color; D003890:Desiccation; D005079:Excipients / Q000737:chemistry*; D006358:Hot Temperature; D007202:Indicators and Reagents; D010316:Particle Size; D011208:Powders
chemical_list: D005079:Excipients; D007202:Indicators and Reagents; D011208:Powders