This book describes the design, physicochemical characterisation and clinical evaluation of bioadhesive drug delivery systems for photodynamic therapy of difficult-to-manage vulval neoplasias and dysplasias. In photodynamic therapy (PDT), a combination of visible light and a sensitising drug causes the destruction of selected cells. ALA is commonly delivered to the vulva using creams or solutions, which are covered with an occlusive dressing to aid retention and enhance drug absorption. Such dressings are poor at staying in place at the vulva, where shear forces are high in mobile patients. To overcome the problems associated with delivery of ALA to the vulva, we produced a bioadhesive patch by a novel laminating procedure. The ALA loading was 38 mg cm-2. Patches were shown to release more ALA over 6 hours than the proprietary cream. The ALA concentration in tissue at 2.375 mm was an order of magnitude greater than that found to be cytotoxic to HeLa cells. Clinically, the patch was used in successful PDT of vulval intraepithelial neoplasia, lichen sclerosus, squamous hyperplasia, Paget's disease and vulvodynia.