XENON XE 133-V.S.S.
Clinical safety rating: caution
Comprehensive clinical and safety monograph for XENON XE 133-V.S.S. (XENON XE 133-V.S.S.).
Xenon Xe-133 is a radioactive gas that emits beta and gamma radiation. It distributes to the lungs and is used for ventilation-perfusion imaging. Its mechanism is based on regional distribution in the lungs, reflecting ventilation. It does not have pharmacological activity.
| Metabolism | Inert gas; not metabolized. Excreted unchanged via the lungs (>95%) after inhalation. |
| Excretion | Eliminated almost entirely via exhalation through the lungs (>95%); negligible renal or biliary/fecal excretion. |
| Half-life | Terminal elimination half-life of approximately 3.5 minutes, corresponding to rapid washout from lungs following cessation of inhalation. |
| Protein binding | Negligible (<5%), not bound to plasma proteins. |
| Volume of Distribution | Approximately 4.5 L/kg, indicating extensive distribution into well-perfused tissues (brain, heart) due to high lipid solubility. |
| Bioavailability | 100% via inhalation; not administered by other routes. |
| Onset of Action | Immediate (within seconds) after inhalation, due to rapid diffusion into brain tissue. |
| Duration of Action | Very short, approximately 3-5 minutes post-inhalation; clinical effects dissipate quickly upon discontinuation. |
5-10 mCi (185-370 MBq) inhaled as a single dose for pulmonary ventilation imaging.
| Dosage form | GAS |
| Renal impairment | No dose adjustment required as Xenon Xe 133 is eliminated via exhalation. |
| Liver impairment | No dose adjustment required as Xenon Xe 133 is not hepatically metabolized. |
| Pediatric use | 0.3-0.5 mCi/kg (11.1-18.5 MBq/kg) inhaled, not to exceed 10 mCi (370 MBq). |
| Geriatric use | No specific adjustment; use lowest effective dose due to potential for diminished pulmonary function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for XENON XE 133-V.S.S. (XENON XE 133-V.S.S.).
| Breastfeeding | There are no data on the excretion of Xenon Xe 133 in breast milk. Due to its short half-life (approximately 5.2 days for Xe-133) and rapid elimination via exhalation, systemic absorption from maternal milk is negligible. However, radioactivity may be present in milk. Lactating women should stop breastfeeding for at least 24 hours after administration or pump and discard milk during that period. The milk-to-plasma ratio (M/P) is not established. |
| Teratogenic Risk | Xenon Xe 133 is a radioactive gas used for diagnostic imaging. Radiation exposure carries a risk of teratogenesis, particularly during the first trimester. The fetal radiation dose from a typical study is low (less than 5 mGy), which is below the threshold for deterministic effects. However, the stochastic risk of childhood cancer is increased, and the procedure is generally avoided in pregnancy unless the benefit outweighs the risk. Second and third trimester exposure poses lower risk for congenital malformations but still carries potential for later carcinogenesis. |
■ FDA Black Box Warning
None - Xenon Xe-133 is a diagnostic radiopharmaceutical; no FDA black box warning exists.
| Serious Effects |
["Known hypersensitivity to xenon or any component","Pregnancy: contraindicated unless essential (category C)","Breastfeeding: temporarily discontinue if administration necessary"]
| Precautions | ["Radiation exposure risk; use only when diagnostic benefit outweighs risk","Pregnancy and lactation: consider alternatives due to potential fetal harm","Pediatric use: adjust dosage based on weight","Hypersensitivity reactions may occur but are rare"] |
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| Fetal Monitoring | Fetal radiation dose calculation should be performed for pregnant patients. Confirm pregnancy status before administration. Vital signs and fetal heart rate monitoring are not routinely required but may be considered if maternal condition warrants. No specific antidote or additional monitoring for the radiotracer itself is needed. |
| Fertility Effects | No known direct effects on fertility in humans from diagnostic use of Xenon Xe 133. Radiation doses from a single procedure are far below those associated with gonadal toxicity. Theoretical risk of stochastic damage to germ cells exists but is negligible at diagnostic levels. |