Term used to define a pharmaceutical, having a activity center containing a metal. Platinum (cisplatin, carboplatin) and gold (Auranofin) compounds are well-known in cancer therapy whereas some other gold compounds (aurithiomalate, aurothioglucose) are important antiarthritic drugs. A wide range of Tc compounds (e.g. Tc-labelled antibodies, Tc-mercaptoacetyl glycine complex) are used for diagnostic imaging of renal, cardiac and cerebral functions and of various forms of cancer. Gadolinium (III) polyaminopolycarboxylic crown complexes are widely used as contrast agents in magnetic resonance imaging.