title: Crystallization speed of salbutamol as a function of relative humidity and temperature.
abstract: Spray dried salbutamol sulphate and salbutamol base particles are amorphous as a result of spray drying. As there is always the risk of recrystallization of amorphous material, the aim of this work is the evaluation of the temperature and humidity dependent recrystallization of spray dried salbutamol sulphate and base. Therefore in-situ Powder X-ray Diffraction (PXRD) studies of the crystallization process at various temperature (25 and 35 °C) and humidity (60%, 70%, 80%, 90% relative humidity) conditions were performed. It was shown that the crystallization speed of salbutamol sulphate and base is a non-linear function of both temperature and relative humidity. The higher the relative humidity the higher is the crystallization speed. At 60% relative humidity salbutamol base as well as salbutamol sulphate were found to be amorphous even after 12 h, however samples changed optically. At 70% and 90% RH recrystallization of salbutamol base is completed after 3 h and 30 min and recrystallization of salbutamol sulphate after 4h and 1h, respectively. Higher temperature (35 °C) also leads to increased crystallization speeds at all tested values of relative humidity.
authors.affiliation: Research Center Pharmaceutical Engineering GmbH, Inffeldgasse 13, Graz, Austria. Electronic address: sarah.zellnitz@rcpe.at.
authors.forename: Sarah
authors.initials: S
authors.lastname: Zellnitz
authors.affiliation: PANalytical B.V., Almelo, Lelyweg 1, Almelo, The Netherlands.
authors.forename: Olga
authors.initials: O
authors.lastname: Narygina
authors.affiliation: Anton Paar GmbH, Anton-Paar-Straße 20, Graz, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Resch
authors.affiliation: Austrian Centre for Electron Microscopy and Nanoanalysis, TU Graz, Steyrergasse 17/III, Graz, Austria.
authors.forename: Hartmuth
authors.initials: H
authors.lastname: Schroettner
authors.affiliation: Research Center Pharmaceutical Engineering GmbH, Inffeldgasse 13, Graz, Austria.
authors.forename: Nora Anne
authors.initials: NA
authors.lastname: Urbanetz
mesh_terms: D000420:Albuterol / Q000737:chemistry*; D003460:Crystallization; D003890:Desiccation; D006813:Humidity; D013696:Temperature
chemical_list: D000420:Albuterol
keywords: Amorphicity; Inhalation; Powder X-ray diffraction; Salbutamol base; Salbutamol sulphate; Spray drying