Xenon, Xe-133
(Xenon)Xenon, Xe-133 Prescribing Information
Xenon Xe 133 Gas has been shown to be valuable for diagnostic inhalation studies for the evaluation of pulmonary function, for imaging the lungs and may also be applied to assessment of cerebral blood flow.
Xenon Xe 133 Gas is administered by inhalation from a closed respirator system or spirometer. The final patient dose should be measured by a suitable radioactivity calibration system immediately prior to administration.
The recommended activity range employed for inhalation by the average patient (70 kg) is:
Pulmonary function including imaging: 74 to 1110 megabecquerels (2 to 30 millicuries)
Cerebral blood flow: 370 to 1110 megabecquerels (10 to 30 millicuries)
This may be administered as a bolus into the tubing near the patient's mouthpiece or mask after the completion of a tidal exhalation, or by rebreathing for a period of approximately 5 minutes of the Xenon Xe 133 gas in equilibrium with the air contained in the closed system at concentrations of the radionuclide that may vary from 37 to 222 megabecquerels (1.0 to 6.0 millicuries) per liter.
None known.
Adverse reactions specifically attributable to Xenon Xe 133 Gas have not been reported.
Xenon Xe 133 Gas is for diagnostic inhalation use only. It is supplied in vials containing either 370 or 740 megabecquerels (10 or 20 millicuries) of Xenon Xe 133 Gas in 2 milliliters of carrier xenon and atmospheric air.
Xenon Xe 133 Gas is chemically and physiologically similar to elemental xenon, a non-radioactive gas which is physiologically inert except for anesthetic properties at high doses.
Xenon Xe 133 is produced by fission of Uranium U 235. At the time of calibration, it contains no more than 0.3% Xenon Xe 133m, no more than 1.5% Xenon Xe 131m, no more than 0.06% Krypton Kr 85 and no more than 0.01% Iodine I 131, with no less than 99.9% total radioactivity as radioxenon. Table 1 shows the effect of time on radionuclidic composition.
Percent of Total Radioactivity | |||||
Days | % Xe-133 | % Xe-133m | % Xe-131m | % Kr-85 | % I-131 |
-5 | >98.3 | <0.6 | <1.0 | <0.03 | <0.01 |
0 | >98.1 | <0.3 | <1.5 | <0.06 | <0.01 |
7 | >97.2 | <0.08 | <2.5 | <0.15 | <0.02 |
14 | >95.7 | <0.02 | <4.1 | <0.37 | <0.02 |
Xenon Xe 133 is a readily diffusible gas which is neither utilized nor produced by the body. It passes through cell membranes, freely exchanges between blood and tissue, and tends to concentrate more in body fat than in blood, plasma, water or protein solutions. In the concentrations recommended for diagnostic studies, it is physiologically inactive. Inhaled Xenon Xe 133 Gas will enter the alveolar wall and the pulmonary venous circulation via capillaries. Most of the Xenon Xe 133 Gas that enters the circulation from a single breath is returned to the lungs and exhaled after a single pass through the peripheral circulation.