(335g) Pharmacokinetic Model of a Tissue Implantable Cortisol Sensor

Cortisol is an important glucocorticoid hormone whose biochemistry influences numerous physiological and pathological processes. Moreover, it is a biomarker of interest for a number of conditions, including post-traumatic stress disorder (PTSD), Cushingâ??s syndrome, Addisonâ??s disease, and others. Due to both the diurnal cycle and the pulsatile release of cortisol, an implantable biosensor capable of real time monitoring of cortisol concentration in adipose tissue can potentially revolutionize the diagnosis and treatment of these disorders, as well as provide an invaluable research tool. Towards this end, we develop a mathematical model, informed by the physiological literature, to predict dynamic cortisol concentrations in adipose, muscle, and brain tissues, where a significant number of important processes with cortisol occur. The mathematical model was applied to both a healthy adult male, as well as a model Cushingâ??s disease patient. Values predicted by the model were verified against reported measurements from the physiological literature. Our model can be used to inform the design of an implantable sensor, by optimizing the sensor dissociation constant, apparent delay time, and magnitude of the sensor output versus system dynamics. Measurements from such a sensor would help to determine systemic cortisol levels, providing much needed insight for proper medical treatment for various cortisol-related conditions.