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

abstract

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%. (c) 2007 Wiley-Liss, Inc. and the American Pharmacists Association.

keywords

NEAR-INFRARED SPECTROSCOPY; BETA-CYCLODEXTRIN DODECAHYDRATE; ANHYDROUS THEOPHYLLINE; STATE REACTIONS; PHYSICAL STABILITY; WATER DIFFUSION; MATRIX TABLETS; VAPOR SORPTION; H/D EXCHANGE; WET MASSES

subject category

Pharmacology & Pharmacy; Chemistry

authors

Amado, AM; Nolasco, MM; Ribeiro-Claro, PJA

our authors

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