117mSn-HTC (117mSn-Tin Colloid, Synovetin OA) is developed and was brought on the market as a radiosynovectomy treatment for veterinary applications. The drug is a colloidal form of 117mSn particles in a restricted size range that does not escape from a joint when injected as arthritis therapeutic (i.e. radiosynoviorthesis or RSO). The drug was introduced on the (veterinary) market in June 2018. The drug is under further development for human application. 117mSn-HTC is a nuclear veterinary drug, available for application in dogs, cats, horses, camels and dromedaries. The molecule is not available for human use, but it is now under preparation for Phase I human RSO clinical trials in Canada.