The KDA was a government agency on the planet Qo'noS responsible for the monitoring and distribution of medical substances.
At some point prior to 2366, this agency determined that lucovexitrin, a dietary medication used by the women of the Central Plains Area, was too toxic and banned its distribution. (TNG: "Hollow Pursuits")
This agency was mentioned in an okudagram which listed and described five substances that had the potential to cause disruptions in the systems aboard a Federation starship.