Controlled porosity‐osmotic pump pellets of a poorly water‐soluble drug using sulfobutylether‐β‐cyclodextrin, (SBE)7M‐β‐CD, as a solubilizing and osmotic agent

The objective of this work was to demonstrate that the incorporation of sulfobutylether‐β‐cyclodextrin, (SBE)7M‐β‐CD, results in the complete and sustained release of a sparingly water‐soluble drug, prednisolone (PDL) from controlled porosity‐osmotic pump pellets (CP‐OPP). PDL and CD were prepared in various formulations (physical mixtures and presumed preformed complex). Several factors influencing drug and CD release were explored, and the probable mechanisms of drug release were probed and discussed. A significant improvement in the release of PDL from the CP‐OPPs was observed by the incorporation of CD relative to the coated pellet formulation containing lactose in place of the CD. The release profiles of PDL depend on the molar ratio of CD to PDL, thickness of the microporous membrane, and osmotic pressure difference across the membrane. PDL appears to be released as an in situ complex with CD via mainly osmotic pumping during at least the initial portion of the release profiles. © 2007 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 96: 2364–2374, 2007