Background: Dexamethasone (DEX) is used in a variety of implantable medical devices to decrease inflammation and improve outcomes. The implantable Eversense® CGM System (Senseonics, Inc.) includes a silicone collar which slowly releases DEX acetate throughout the lifetime of the sensor. Studies were performed to characterize the potential user risk to dexamethasone acetate exposure.
Methods: Clinical trial subjects underwent frequent blood sampling for analysis of plasma DEX levels. Chemical testing of 90-day sensor explants was used to measure residual DEX content. Finally, a post market clinical follow-up study (PMCF) is currently ongoing which monitors the rate of serious device-related, procedure-related, or drug (DEX) related adverse events through approximately 24 months.
Results: In two trials (N=161, 86 with 2 sensors, 75 with 1 sensor), blood tests were performed to the 2 ng/mL level with no detectable plasma DEX. In a third trial (N=35), the limit of detection was reduced to 0.050 ng/mL. Blood samples from 8 patients inserted with one sensor had no measurable DEX plasma levels. Among 27 patients inserted with two sensors, the highest level of DEX detected was 0.114 ng/mL on day 2 post-insertion. All samples were below the detectable limit by day 8. Literature review states at plasma levels < 1 ng/mL no systemic effect occurs. Testing of sensor explants determined that 0.3 mg of DEX is eluted over 90 days. No adverse events related to exposure to DEX have been reported to date in the PMCF
Conclusions: Dexamethasone acetate, which was selected to reduce the inflammatory response of the implantable sensor, was found to be safe. Plasma DEX levels after extended use are well below the concentration necessary for a pharmacological response, demonstrating safety of the Eversense Sensor with regard to clinical adverse effects attributable to chronic DEX exposure and that this risk should not grow over time.
E.L. Kelley: Employee; Self; Senseonics. H. Haridas: Employee; Self; Senseonics. C. Lorenz: Employee; Self; Senseonics.