Piroxicam/2‐Hydroxypropyl‐β‐Cyclodextrin Inclusion Complex Prepared by a New Fluid‐Bed Coating Technique

This work was aimed at investigating the feasibility of fluid‐bed coating as a new method to prepare cyclodextrin inclusion complex. The inclusion complex of the model drug piroxicam (PIX) and 2‐hydroxypropyl‐β‐cyclodextrin (HPCD) in aqueous ethanol solution was sprayed and deposited onto the surface of the pellet substrate upon removal of the solvent. The coating process was fluent with high coating efficiency. Scanning electron microscopy revealed a coarse pellet surface, and a loosely packed coating structure. Significantly enhanced dissolution, over 90% at 5 min, was observed at stoichiometric PIX/HPCD molar ratio (1/1) and at a ratio with excessive HPCD (1/2). Differential scanning calorimetry and powder X‐ray diffractometry confirmed absence of crystallinity of PIX at PIX/HPCD molar ratio of 1/1 and 1/2. Fourier transform‐infrared spectrometry and Raman spectrometry revealed interaction between PIX and HPCD adding evidence on inclusion of PIX moieties into HPCD cavities. Solid‐state 13C NMR spectrometry indicated possible inclusion of PIX through the pyridine ring. It is concluded that fluid‐bed coating has potential to be used as a new technique to prepare cyclodextrin inclusion complex. © 2008 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:665-675, 2009