Xenon Xe 127 »Xenon Xe 127is a gas suitable for inhalation in diagnostic studies.Xenon 127is a radioactive nuclide that may be prepared from the bombardment of a cesium 133target with high-energy protons.It contains not less than 85.0percent and not more than 115.0percent of the labeled amount of 127Xe at the calibration date indicated on the labeling. Packaging and storage— Preserve in single-dose vials having leak-proof stoppers,at room temperature.The vials are enclosed in appropriate lead radiation shields.The vial content may be diluted with air and is packaged at atmospheric pressure. Labeling— Label it to include the following:the name of the preparation;the container volume,MBq (mCi)of 127Xe per container;the amount of 127Xe expressed as megabecquerels (millicuries)per mL;the intended route of administration;recommended storage conditions;the date of calibration;the expiration date;the name,address,and batch number of the manufacturer;the statement “Caution—Radioactive Material”;and a radioactive symbol.The labeling contains a statement of radionuclide purity,identifies probable radionuclidic impurities,and indicates permissible quantities of each impurity.The labeling indicates that in making dosage calculations,correction is to be made for radioactive decay,and also indicates that the radioactive half-life of 127Xe is 36.41days. Radionuclide identification (see Radioactivity á821ñ)— Its gamma-ray spectrum is identical to that of a known specimen of xenon 127that exhibits major photopeaks at 202.8keV,and 172.1keV,and 375.0keV.Minor photopeaks from other xenon radioisotopes,namely Xe 129m (197keV)and Xe 131m (164keV)may also be present. Radionuclidic purity— Using a suitable counting assembly (see Selection of a Counting Assemblyunder Radioactivity á821ñ),determine the radioactivity of the Xe 127in the gas by use of a calibrated system as directed under Radioactivity á821ñ.Using the gamma-ray spectrum,determine the energy of each gamma photopeak.Identify each radionuclide present,and using the established detector efficiency and known gamma abundance,calculate the quantity of each radionuclide present in the specimen in MBq (mCi).The amount of Xe 127present in the specimen is not less than 80%;the quantity of either Xe 131m or Xe 129m does not exceed 10%,and no other radioisotope exceeds 1%. Assay for radioactivity— Using a suitable counting assembly (see Selection of a Counting Assemblyunder Radioactivity á821ñ),determine the radioactivity,in MBq (mCi),of Xe 127in each container by use of a calibrated system as directed under Radioactivity á821ñ. Auxiliary Information— Staff Liaison:Andrzej Wilk,Ph.D.,Senior Scientific Associate Expert Committee:(RMI)Radiopharmaceuticals and Medical Imaging Agents USP28–NF23Page 2037 Phone Number:1-301-816-8305