This past April, methylphenidate (Daytrana, Shire) was approved as a transdermal drug delivery system (TD-DDS) for the treatment of attention deficit hyperactivity disorder. And many more patches are on the horizon. Novartis is seeking Food & Drug Administration approval for its rivastigmine (Exelon) patch to aid in the treatment of Alzheimer's disease. Researchers in the United Kingdom are working on a TD-DDS to deliver synthetic cannabinoids for use as antiemetics and appetite stimulants in patients with AIDS and cancer.