Abstract: A device for measurement and monitoring of a subject simultaneously with transdermal or transmucosal delivery of a therapeutic agent at a contact site with the subject's skin includes a transdermal sensor adapted and configured to detect a specific indicator that is either the therapeutic agent itself or a biomarker that is affected by the therapeutic agent, a therapeutic-agent-containing formulation for passive or active transdermal drug delivery, wherein the formulation includes a dermoadhesive agent to adhere the underside of the sensor housing unit to the skin, and a separate circumferential self-adhesive patch can be adapted and configured to hold the sensor and its housing unit firmly to the skin at the contact site for multiple days.