Xenon Xe 127 (Systemic)
VA CLASSIFICATION
Primary: DX201
Commonly used brand name(s): Xenon Xe 127 Gas.
Note: For a listing of dosage forms and brand names by country availability, see Dosage Forms section(s).
*Not commercially available in the U.S.
Category:
Diagnostic aid, radioactive (pulmonary disease)—
Indications
Accepted
Pulmonary function studies and
Lung imaging, radionuclide—Xenon Xe 127 for inhalation (in ventilation studies) is indicated in the evaluation and assessment of suspected pulmonary emboli. {04} {16} Lung ventilation imaging is almost always performed in conjunction with lung perfusion imaging in order to better differentiate pulmonary embolism from obstructive-type lung diseases. {10} {11} {12} {14}
—Pulmonary ventilation imaging is also beneficial in the evaluation of lung diseases that affect ventilation, such as asthma, pulmonary emphysema, bronchiectasis, and carcinoma of the lung. {01} {14}
Physical Properties
Nuclear data {01} {02} {03} {04} {16}:
| Radionuclide * (half-life) |
Decay constant |
Mode of decay |
Principal photons (keV) |
Mean number of photons/ disintegration |
|---|---|---|---|---|
| Xe 127 (36.41 days) |
0.000793 h -1 |
Electron capture (to Iodine I 127) |
Gamma (172.1) |
0.247 |
| Gamma (202.8) |
0.681 |
|||
| Gamma (375) |
0.174 |
Pharmacology/Pharmacokinetics
Mechanism of action/Effect:
Xenon Xe 127 is a physiologically inert gas that is relatively insoluble {04}. It diffuses easily, passing through cell membranes and exchanging freely between blood and tissue. It is distributed in the lungs in a manner similar to that of air, thus representing the regions of the lung that are aerated. The gamma photons of xenon Xe 127 can then be employed to obtain an image of lung ventilation. Xenon Xe 127's presence in various stages of breathing is thus determined. Scintigraphs taken during the washout period, as the patient breathes room air, will show any obstruction in the airways as regions of radioactive gas trapping or retention. (In the presence of an abnormal or near normal Tc 99m albumin aggregated perfusion study, a normal ventilation study favors a diagnosis of pulmonary emboli. However, the presence of xenon Xe 127 gas trapping, during washout imaging, in areas of abnormal perfusion, favors a diagnosis of chronic-type obstructive pulmonary disease.) {01} {02} {03} {04} {14} {16}
Distribution:
When inhaled, xenon Xe 127 passes through the airways into the alveoli. Because of its insolubility, very little passes into the pulmonary venous circulation via capillaries. Most of it returns to the lungs and is exhaled after passing through the peripheral circulation. Inhaled xenon Xe 127 gas will mix with the air in the lungs and come to an equilibrium distribution if the patient is in a closed ventilation system. {01} {04} {14}
Radiation dosimetry:
{07}
| Estimated absorbed radiation dose* With single inhalation (30 sec breath-hold) |
||
|---|---|---|
| Organ |
mGy/MBq |
rad/mCi |
| Lungs |
0.00034 |
0.0013 |
| Pancreas |
0.00014 |
0.00052 |
| Red marrow |
0.00014 |
0.00052 |
| Adrenals |
0.00013 |
0.00048 |
| Bone surfaces |
0.00012 |
0.00044 |
| Stomach wall |
0.00012 |
0.00044 |
| Small intestine |
0.00012 |
0.00044 |
| Large intestine wall (upper) |
0.00012 |
0.00044 |
| Liver |
0.00012 |
0.00044 |
| Spleen |
0.00012 |
0.00044 |
| Uterus |
0.00012 |
0.00044 |
| Bladder wall |
0.00011 |
0.00041 |
| Breast |
0.00011 |
0.00041 |
| Large intestine wall (lower) |
0.00011 |
0.00041 |
| Kidneys |
0.00011 |
0.00041 |
| Ovaries |
0.00011 |
0.00041 |
| Thyroid |
0.000089 |
0.00033 |
| Testes |
0.000083 |
0.00031 |
| Other tissue |
0.000099 |
0.00037 |
| Effective dose: 0.00014 mSv/MBq (0.00052 rem/mCi)* |
||
| Organ |
Estimated absorbed radiation dose* With inhalation (rebreathing from closed spirometer) |
|||
|---|---|---|---|---|
| For 5 minutes |
For 10 minutes |
|||
| mGy/ MBq |
rad/ mCi |
mGy/ MBq |
rad/ mCi |
|
| Red marrow |
0.00090 |
0.0033 |
0.0015 |
0.0056 |
| Pancreas |
0.00088 |
0.0033 |
0.0014 |
0.0052 |
| Uterus |
0.00087 |
0.0032 |
0.0014 |
0.0052 |
| Small intestine |
0.00085 |
0.0031 |
0.0014 |
0.0052 |
| Lungs |
0.00082 |
0.0030 |
0.0011 |
0.0041 |
| Bone surfaces |
0.00081 |
0.0030 |
0.0013 |
0.0048 |
| Stomach wall |
0.00081 |
0.0030 |
0.0013 |
0.0048 |
| Adrenals |
0.00080 |
0.0030 |
0.0013 |
0.0048 |
| Large intestine wall (upper) |
0.00080 |
0.0030 |
0.0013 |
0.0048 |
| Ovaries |
0.00080 |
0.0030 |
0.0013 |
0.0048 |
| Spleen |
0.00078 |
0.0029 |
0.0013 |
0.0048 |
| Bladder wall |
0.00077 |
0.0029 |
0.0013 |
0.0048 |
| Large intestine wall (lower) |
0.00077 |
0.0029 |
0.0013 |
0.0048 |
| Kidneys |
0.00075 |
0.0028 |
0.0012 |
0.0044 |
| Liver |
0.00075 |
0.0028 |
0.0012 |
0.0044 |
| Breast |
0.00065 |
0.0024 |
0.0010 |
0.0037 |
| Thyroid |
0.00060 |
0.0022 |
0.00098 |
0.0036 |
| Testes |
0.00058 |
0.0021 |
0.00096 |
0.0036 |
| Other tissue |
0.00065 |
0.0024 |
0.0011 |
0.0041 |
| Radionuclide |
Effective dose* |
|||
|---|---|---|---|---|
| Rebreathing for 5 minutes |
Rebreathing for 10 minutes |
|||
| mSv/ MBq |
rem/ mCi |
mSv/ MBq |
rem/ mCi |
|
| Xe 127 |
0.00077 |
0.0028 |
0.0012 |
0.0044 |
Elimination:
Pulmonary.
Precautions to Consider
Carcinogenicity/Mutagenicity
Long-term animal studies to evaluate carcinogenic or mutagenic potential of xenon Xe 127 have not been performed. {01}
Pregnancy/Reproduction
Pregnancy—
Studies have not been done with xenon Xe 127 in humans.
The possibility of pregnancy should be assessed in women of child-bearing potential. Clinical situations exist where the benefit to the patient and fetus, based on information derived from radiopharmaceutical use, outweighs the risks from fetal exposure to radiation. In these situations, the physician should use discretion and reduce the radiopharmaceutical dose to the lowest possible amount. {13}
Studies have not been done in animals.
FDA Pregnancy Category C. {01}
Breast-feeding
It is not known whether xenon Xe 127 is distributed into breast milk. However, risk to the infant from radiation exposure is considered negligible. Because of xenon Xe 127's poorly soluble nature, the amount that enters the venous circulation is not significant. Also, the small amount of xenon Xe 127 gas that passes into the venous circulation returns rapidly to the lungs to be exhaled. {01} {04} {14}
Pediatrics
There have been no specific studies evaluating the safety and efficacy of xenon Xe 127 in pediatric patients. When this radiopharmaceutical is used in children, the diagnostic benefit should be judged to outweigh the potential risk of radiation. {13}
Geriatrics
Appropriate studies on the relationship of age to the effects of xenon Xe 127 have not been performed in the geriatric population. However, no geriatrics-specific problems have been documented to date.
Drug interactions and/or related problems
See Diagnostic interference.
Diagnostic interference
The following have been selected on the basis of their potential clinical significance (possible effect in parentheses where appropriate)—not necessarily inclusive (» = major clinical significance):
With results of this test
Due to other medications
Anesthetics, inhalation or
Diazepam (distribution of xenon Xe 127 in the lung may be affected, with more activity shifting to the top of the lung and less to the bottom, due to a change in the gradient of ventilation, from nondependent to dependent lung, caused by these medications {06})
Alcohol, chronic use or
Clofibrate or
Parenteral nutrition, total (TPN) (these medications may alter hepatic function [e.g., fatty liver disease as a result of TPN therapy]; because xenon is lipid soluble, appearance of radioactivity in liver during washout phase of ventilation study is theoretically possible; hepatic retention of xenon Xe 127 may be incorrectly attributed to other disorders associated with fatty liver infiltration [e.g., diabetes mellitus] that may also promote accumulation of xenon Xe 127 in the liver {06} {14} {15})
Due to medical problems or conditions
Diabetes mellitus or
Hyperlipidemia or
Obesity (fatty liver infiltration associated with these disorders may promote accumulation of lipid-soluble xenon in the liver {06})
Medical considerations/Contraindications
See Diagnostic interference.
Side/Adverse Effects
There are no known side/adverse effects associated with the use of xenon Xe 127 as a diagnostic aid. {01}
Patient Consultation
As an aid to patient consultation, refer to Advice for the Patient, Radiopharmaceuticals (Diagnostic).
In providing consultation, consider emphasizing the following selected information (» = major clinical significance):
Description of use
Action in the body: Localization in airways of the lung
Visualization of radioactivity in lungs
Small amounts of radioactivity used in diagnosis; radiation received is low and considered safe
Before having this test
» Conditions affecting use, especially:
Pregnancy—Risk to fetus from radiation exposure as opposed to benefit derived from use should be considered
Breast-feeding—Not known if distributed into breast milk; however, risk to infant from radiation exposure is considered negligible
Use in children—Risk of radiation exposure as opposed to benefit derived from use should be considered
Preparation for this test
Special preparatory instructions may be given; patient should inquire in advance
Precautions after having this test
No special precautions
General Dosing Information
Radiopharmaceuticals are to be administered only by or under the supervision of physicians who have had extensive training in the safe use and handling of radioactive materials and who are authorized by the appropriate Federal or State agency, if required, or, outside the U.S., the appropriate authority. {13} {14}
Xenon Xe 127 should not be allowed to stand in tubing or respirator containers since it adheres to some plastics and rubber, causing a reduction in the administered activity. {01} {14}
Xenon Xe 127 is administered by inhalation, as a mixture with air, from a shielded, closed respirator system or spirometer. {01} {02}
Adequate trapping or exhausting of exhaled xenon Xe 127 in accordance with state requirements is essential to reduce contamination of air by airborne Xe 127. {02} {16}
Ventilation imaging is performed as the patient inhales the radioactive xenon. Successive images are obtained while the patient holds his or her breath (single-breath-hold image) and during various phases of breathing (rebreathing and washout from lungs). {02} {14} {15} {16}
Safety considerations for handling this radiopharmaceutical
Improper handling of this radiopharmaceutical may cause radioactive contamination. Guidelines for handling radioactive material have been prepared by scientific, professional, state, federal, and international bodies and are available to the specially qualified and authorized users who have access to radiopharmaceuticals. {17}
Inhalation Dosage Forms
XENON Xe 127
Usual adult and adolescent administered activity
Inhalation, 185 to 370 megabecquerels (5 to 10 millicuries).
Note: When the ventilation study with xenon Xe 127 is combined with a lung perfusion study using technetium Tc 99m albumin aggregated, xenon Xe 127 may be administered immediately following Tc 99m perfusion imaging. {01} {02}
Usual pediatric administered activity
Dosage must be individualized by physician. The minimum recommended total dosage is 74 megabecquerels (2 millicuries). {09} {14}
Usual geriatric administered activity
See Usual adult and adolescent administered activity .
Size(s) usually available:
U.S.—
Not commercially available.
Canada—
185 megabecquerels (5 millicuries) per 2-mL-size vial (Rx) [Xenon Xe 127 Gas]
Packaging and storage:
Store between 15 and 30 °C (59 and 86 °F). {01}
Stability:
Xenon Xe 127 gas should not be administered after 120 days from the date of calibration stated on the label. {01}
Adheres to some plastics and rubber; to avoid a reduction in the administered activity, do not allow to stand in tubing or respirator container. {01} {14}
Note: Caution—Radioactive material.
Revised: 08/02/1994
References
- Xenon Xe 127 Gas package insert (Mallinckrodt—US), Rev 12/82.
- Chilton HM, Witcofski RL. Nuclear pharmacy—an introduction to the clinical application of radiopharmaceuticals. Philadelphia: Lea & Febiger, 1986: 140-2.
- Saha GB. Fundamentals of nuclear pharmacy, 2nd ed. New York: Springer-Verlag; 48, 215.
- Reviewers' comments as per monograph revision of 12/2/87.
- MIRD Primer for Absorbed Dose Calculations, SNM, Report no. 9.
- Hladik WB, Saha GB, Study KT. Essentials of nuclear medicine science. Baltimore: Williams & Wilkins, 1987: 211.
- Task Group of Committee 2 of the International Commission on Radiological Protection. Annals of the ICRP. ICRP Publication 53—Radiation dose to patients from radiopharmaceuticals. New York: Pergamon Press, 1988: 341.
- USP Radiopharmaceuticals Panel meeting on 08/04/92.
- Pediatric dosages recommended by USP Radiopharmaceuticals Advisory panelists, 8/92.
- PIOPED Investigators. Value of the ventilation/perfusion scan in acute pulmonary embolism: results of the prospective investigation of pulmonary embolism diagnosis (PIOPED). JAMA 1990; 263: 2753-9.
- Bone RC. Ventilation/perfusion scan in pulmonary embolism: `the emperor is incompletely attired.' JAMA 1990; 263: 2794-5.
- Hull RD, Hirsh J, Carter CJ, et al. Diagnostic value of ventilation-perfusion lung scanning in patients with suspected pulmonary embolism. Chest 1985; 88(6): 819-28.
- USP Radiopharmaceuticals Advisory Panel meeting of 05/08/91.
- Reviewers' comments per 09/27/93 monograph revision.
- Swanson DP, Chilton HM, Thrall JH. Pharmaceuticals in medical imaging. New York: Macmillan, 1990: 409.
- Alderson PO, Line BR. Scintigraphic evaluation of regional pulmonary ventilation. Semin Nucl Med 1980; 10(3): 218-42.
- Reviewers' responses to Ballot of 5/11/94.
- Hayes M, Taplin GV. Lung imaging with radioaerosols for the assessment of airway disease. Semin Nucl Med 1980; 10(3): 243-51.
