Devices and methods are provided for transdermal administration of a pharmaceutical agent to a patient in need thereof. The device includes a substrate, a plurality of discrete reservoirs in the substrate, one or more pharmaceutical agents stored in the reservoirs, discrete reservoir caps that prevent the pharmaceutical agent from passing out from the reservoirs until desired, control means for actuating release of the one or more pharmaceutical agents from one or more of the reservoirs by disintegrating or permeabilizing the reservoir caps, means for securing the device to the skin of the patient, and means for transporting the pharmaceutical agent to the skin following release from the one or more of the reservoirs. In another embodiment, the device is adapted for diagnostic sensing instead of or in addition to drug delivery.