A sensor that may be implanted within a living animal (e.g., a human) and may be used to measure an analyte (e.g., glucose or oxygen) in a medium (e.g., interstitial fluid, blood, or intraperitoneal fluid) within the animal. The sensor may include a sensor housing and an analyte indicator covering at least a portion of the sensor housing. The sensor may include a drug-eluting matrix that covers at least a portion of the analyte indicator. The drug-eluting matrix may include one or more openings configured to allow the medium to pass through the drug-eluting matrix and come into contact with the analyte indicator. The sensor may include one or more therapeutic agents. The one or more therapeutic agents may reduce deterioration of the analyte indicator. The one or more therapeutic agents may be incorporated within the drug-eluting matrix.
