125IUdR

**Semantic type:** Pharmacologic Substance

**Definition:** A radiopharmaceutical comprised of a thymidine analog, 5-iodo-2''-deoxyuridine (idoxuridine), labelled with the Auger electron emitter Iodine 125 that has been used as an assay for testing cell-mediated cytotoxicity and exhibits cytotoxicity by incorporating into DNA, causing DNA strand breaks. (NCI04)

**Synonyms:** - 125-I Deoxyuridine