title: Phase transformation of erythromycin A dihydrate during fluid bed drying.
abstract: An in-line near infrared (NIR) spectrometer was employed to monitor phase transformations of erythromycin dihydrate during a miniaturized fluid bed drying process. The pellets, containing 50% (w/w) erythromycin dihydrate and 50% (w/w) microcrystalline cellulose, were dried at 30, 45, and 60 degrees C. Principal component analysis was used to determine solid-state changes. For this purpose the wavelength range of 1360-2000 nm was selected and preprocessed to remove multiplicative effects. Transformation to erythromycin dehydrate was observed for the pellets dried at 45 and 60 degrees C by NIR spectrometry and X-ray powder diffractometry (XRPD). The formation of erythromycin dehydrate was observed at a moisture content 1.4% (w/w) (mass of water per dry mass of sample) while at 1.8% (w/w) neither XRPD nor NIR were able to detect dehydration. Transformation to erythromycin dehydrate therefore depends strongly on the moisture content of the pellets.
authors.affiliation: Division of Pharmaceutical Technology, Faculty of Pharmacy, University of Helsinki, PO Box 56, 00014 Helsinki, Finland. meike.romer@helsinki.fi
authors.forename: Meike
authors.initials: M
authors.lastname: Römer
authors.forename: Jyrki
authors.initials: J
authors.lastname: Heinämäki
authors.forename: Inna
authors.initials: I
authors.lastname: Miroshnyk
authors.forename: Niina
authors.initials: N
authors.lastname: Kivikero
authors.forename: Niklas
authors.initials: N
authors.lastname: Sandler
authors.forename: Jukka
authors.initials: J
authors.lastname: Rantanen
authors.forename: Jouko
authors.initials: J
authors.lastname: Yliruusi
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry*; D004917:Erythromycin / Q000737:chemistry*; D008904:Miniaturization; D019265:Spectroscopy, Near-Infrared; D014961:X-Ray Diffraction
chemical_list: D000900:Anti-Bacterial Agents; D004917:Erythromycin