Probing pseudopolymorphic transitions in pharmaceutical solids using Raman spectroscopy: Hydration and dehydration of theophylline

• Autor(a) principal: Amado, Ana M.
• Data de Publicação: 2007
• Outros Autores: Nolasco, Mariela M., Ribeiro-Claro, Paulo J. A.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10316/8263; https://doi.org/10.1002/jps.20923

Theophylline is known to undergo vapor phase induced hydrate-anhydrate pseudopolymorphic transformations, which can affect its bioavailability. In this work, the kinetics of the pseudopolymorphic transitions of theophylline crystals in different storage conditions is studied using a vibrational spectroscopic technique. While the hydration is a single-step process with a half-life time of ca. 5 h, the dehydration occurs through a two-step mechanism. In addition, the phase stability of hydrate-anhydrate systems in different relative humidity (RH) conditions was probed. The critical RH for anhydrous teophylline was found to be at ca. 79%, while the critical RH for dehydration is ca. 30%. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96: 1366-1379, 2007