Nitroarginine, or Nω-nitro-L-arginine, is a nitro derivative of the amino acid arginine. It is an inhibitor of nitric oxide synthase and hence a vaso-constrictor and coronary constrictor. As such, it finds widespread use as a biochemical tool in the study of nitric oxide and its biological effects. Nitroarginine has been used in research studying coronary constriction, in the presence of midazolam vasodilatation was unaffected by nitroarginine. Nitroarginine is currently in clinical trials for treating patients with advanced solid tumors.