Darifenacin is a urinary antispasmodic. The oral absorption of darifenacin is poor due to its low solubility and poor bioavailability (15–19%). Darifenacin was complexed with hydroxylropyl beta-cyclodextrin (Hpβ-CD). The best results were obtained with the coevaporation that interacts in a 1？:？1 drug？:？cyclodextrin molar ratio. The solid inclusion complexes were found to be amorphous in the characterization. The dissolution rate of darifenacin from the Hpβ-CD solid inclusion complex was increased compared to the powdered drug. The controlled release buccoadhesive patches for the delivery of darifenacin were prepared using HPMC K100M CR and HPMC K15. The coevaporation complex of the drug was used in the formulation due to its increased saturation solubility and increased ease of dissolution. The patches were evaluated for their surface pH, folding endurance, swelling, mucoadhesive properties, in vitro residence time, vapour transmission test, and in vitro and ex vivo release studies. Formulations Hb2 (2%) and Pb4 (4%) were found to be optimized. These two formulations can be used for buccal delivery of darifenacin which avoids first pass effect and leads to increased bioavailability of darifenacin. 1. Introduction Cyclodextrin is capable of forming inclusion complexes with many drugs by taking up a whole drug molecule, or a part of it, into the cavity of the cyclodextrin molecule. Drug cyclodextrins complexes can improve the clinical usage of drugs by increasing their aqueous solubility, dissolution rate, and pharmaceutical availability [1]. Hpβ-CD can be used to solubilise poorly water-soluble drugs by complexation and then delivery via the buccal or sublingual mucosa may be advantageous for increasing drug absorption. The buccal route has high acceptance due to avoidance of first pass metabolism and possibility of being accessible for controlled drug release. Various bioadhesive mucosal dosage forms have been developed which include adhesive tablets, gels, ointments, and more recently patches. Buccal patches are preferred over adhesive tablets in terms of flexibility and patients comfort.Nowadays bioadhesive polymers receive considerable attention as platforms for buccal controlled delivery due to their ability to localize the dosage form in specific regions to enhance drug bioavailability [2, 3]. Buccal mucosa is a potential site for the delivery of drugs to the systemic circulation. A drug administered through the buccal mucosa enters directly the systemic circulation, thereby minimizing the first-pass hepatic metabolism and adverse gastrointestinal
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