Sustained transdermal drug delivery by grooved microneedle arrays (MNA) can enhance patient compliance, reduce costs, and increase access to treatment. To date the major obstacle in developing such delivery devices is the drug loading capacity required to achieve clinically relevant doses. This proposal sets out a series of studies to develop and validate a novel wearable MNA Band-Aid like patch that can carry a payload sufficient to deliver an effective dose. The Partnering PI, Dr. Sonkusales has developed this state of the art, low-cost technology in his laboratory. To demonstrate the advantages of MNA technology for drug delivery to treat disorders that have a high incidence in military service members and veterans, ketamine and its metabolite 2R, 6R-hydroxynorketamine ((2R, 6R)-HNK) have been chosen as the test compounds of interest. The MNA patches will be evaluated in rats on behavioral endpoints that are relevant to post traumatic stress disorder(PTSD) and chronic pain conditions. Targeting these endpoints to demonstrate the flexibility and functionality of the sustained delivery device will achieve the secondary goal of these studies. That is to provide preclinical evidence in support of developing (2R,6R)-HNK as a therapeutic for PTSD and chronic pain conditions.