Transdermal systems for overactive bladder: principles and practice

The transdermal system for delivery of medication to treat overactive bladder may provide an improved efficacy-to-tolerability ratio by regulating serum drug levels; avoiding gastrointestinal and hepatic metabolism, which is important when the metabolite has a lesser therapeutic index than the parent drug; and achieving clinical efficacy with a lower total drug burden. Additional advantages may include increased compliance and obviation of the need for oral drug administration, which is especially beneficial for the patient who is taking multiple oral medications or is caregiver-dependent. An efficient patch system must preserve the physical integrity of the drug layer, provide adequate adhesion, store and release the drug and permeation-enhancing agent in a predictable manner, promote consistent absorption through the skin regardless of location or skin or subcutaneous tissue differences, demonstrate dose proportionality, maintain skin integrity during product use and removal, and be cosmetically acceptable. A novel transdermal delivery system that incorporates an occlusive layer covering an acrylic adhesive containing the active agent oxybutynin and a skin permeation enhancer has been demonstrated in clinical trials to achieve these goals.