Krypton Kr 81m (Systemic)


VA CLASSIFICATION
Primary: DX201

Commonly used brand name(s): Krypton Kr 81m Gas Generator.

Note: For a listing of dosage forms and brand names by country availability, see Dosage Forms section(s).



Category:


Diagnostic aid, radioactive (pulmonary disease; pulmonary emboli)—

Indications

Note: Bracketed information in the Indications section refers to uses that are not included in U.S. product labeling.

Accepted

Pulmonary function studies—Krypton Kr 81m for inhalation is indicated in pulmonary ventilation studies to assess and evaluate regional pulmonary function in lung diseases. {01} {02} {03} {04} {07} {10} {14}

[Embolism, pulmonary (diagnosis)]—Krypton Kr 81m is used to complement lung perfusion studies to detect pulmonary emboli. {03} {04} {07}


Physical Properties

Nuclear data: {01} {05} {06} {10} {14}



Radionuclide
(half-life)
Mode of
decay
Principal
photon
emissions
(keV)
Mean number
of emissions/
disintegration
Kr 81m
(13.1 seconds)
Isomeric
transition
Gamma (191)
0.66
Kr 81*
(2.1 × 10 5
years)
     
* Decay product.


Pharmacology/Pharmacokinetics

Mechanism of action/Effect:

Krypton Kr 81m diffuses easily, passing through cell membranes and exchanging freely between blood and tissue. It is distributed in the lungs in a manner similar to air, thus representing the regions of the lung that are aerated. The gamma photons of krypton Kr 81m can then be employed to obtain counts per minute per lung or region of the lung, or to display their distribution as a scan. {01} {14}

Distribution:

When inhaled, krypton Kr 81m enters the alveolar wall and passes to the pulmonary venous circulation via capillaries. Most of it that enters the circulation from a single breath returns to the lungs and is exhaled after a single pass through the peripheral circulation. {14}

Radiation dosimetry:
{11}

Estimated absorbed radiation dose*
Organ
mGy/MBq
mrad/mCi
Lungs
0.00021
0.78
Breast
0.0000046
0.017
Pancreas
0.0000035
0.013
Adrenals
0.0000034
0.013
Liver
0.0000034
0.013
Spleen
0.0000031
0.011
Stomach wall
0.0000025
0.0093
Red marrow
0.0000021
0.0078
Bone surfaces
0.0000017
0.0063
Kidneys
0.0000012
0.0044
Large intestine (upper)
0.00000032
0.0012
Small intestine
0.00000027
0.0010
Ovaries
0.00000017
0.00063
Large intestine (lower)
0.00000014
0.00052
Uterus
0.00000013
0.00048
Bladder wall
0.000000068
0.00025
Testes
0.000000017
0.000063
Other tissue
0.0000018
0.0067
Effective dose: 0.000027 mSv/MBq (0.0001 rem/mCi)
* For adults; by continuous inhalation. Data based on the International Commission on Radiological Protection (ICRP) Publication 53—Radiation dose to patients from radiopharmaceuticals. {11}

Elimination:
    Eliminated via lungs. {14}


Precautions to Consider

Carcinogenicity/Mutagenicity

Long-term animal studies to evaluate carcinogenic or mutagenic potential of krypton Kr 81m have not been performed. {14}

Pregnancy/Reproduction

Pregnancy—
Studies have not been done in humans. {14} The possibility of pregnancy should be assessed in women of child-bearing potential. Clinical situations exist where the benefit to the patient and fetus from information derived from radiopharmaceutical use outweighs the risks of fetal exposure to radiation. In these situations, the physician should use discretion and reduce the radiopharmaceutical dose to the lowest possible amount. {09}

Studies have not been done in animals. {14}

FDA Pregnancy Category C. {01} {14}

Breast-feeding

It is not known whether krypton Kr 81m is distributed into breast milk. {14} However, risk to the infant from radiation exposure is considered negligible because of the short half-life of krypton Kr 81m. Also, most of the amount that passes into the venous circulation returns to the lungs to be exhaled. {08} {12} {13}

Pediatrics

Because of the potential risk of radiation exposure, risk-benefit must be considered. Although krypton Kr 81m is used in children, there have been no specific studies evaluating its safety and efficacy in children. {14} When this radiopharmaceutical is used in children, the diagnostic benefit should be judged to outweigh the potential risk of radiation. {09}


Geriatrics


Appropriate studies on the relationship of age to the effects of krypton Kr 81m have not been performed in the geriatric population. However, geriatrics-specific problems that would limit the usefulness of this radiopharmaceutical in the elderly are not expected. {02}


Side/Adverse Effects
At the present time, there are no known side/adverse effects associated with diagnostic doses of krypton Kr 81m. {01} {12} {14}



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: Accumulation of radioactivity in lungs during continuous breathing

Radioactivity retained in lungs during continuous breathing allows visualization

Small amounts of radioactivity used in diagnosis; radiation exposure 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 krypton Kr 81m is distributed into breast milk; however, based on the short half-life of krypton Kr 81m, discontinuation of nursing is not necessary





Use in children—Risk from 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 when used for diagnosis


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 Nuclear Regulatory Commission (NRC) or the appropriate Federal or Agreement State agency, if required or, outside the U.S., the appropriate authority. {14}

The manufacturer's package insert or other appropriate literature should be consulted for optimal times when imaging should be performed.

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. {13}


Inhalation Dosage Forms

KRYPTON Kr 81m USP

Usual adult and adolescent administered activity
Pulmonary function studies
Inhalation (continuous), 37 to 370 megabecquerels (1 to 10 millicuries) of krypton Kr 81m, not to exceed 3.7 gigabecquerel-minutes (100 millicurie-minutes). {14}


Usual pediatric administered activity
Dosage must be individualized by physician.

Usual geriatric administered activity
See Usual adult and adolescent administered activity .

Strength(s) usually available
U.S.—



At calibration time


As rubidium Rb 81, with an activity of 74 to 370 megabecquerels (2 to 10 millicuries) (Rx) [Krypton Kr 81m Gas Generator]

Canada—



At calibration time


As rubidium Rb 81, with an activity of 74 to 370 megabecquerels (2 to 10 millicuries) (Rx) [Krypton Kr 81m Gas Generator{14}]

Note: Thirty-seven megabecquerels (one millicurie) of rubidium Rb 81 yields 35.5 megabecquerels (0.96 millicurie) of krypton Kr 81m at equilibrium. {14}


Packaging and storage:
Store below 40 °C (104 °F), preferably between 15 and 30 °C (59 and 86 °F), unless otherwise specified by manufacturer. {14}

Stability:
Gas generator expires 12 hours after date and time of calibration. {14}

Note: Caution—Radioactive material.




Revised: 04/30/1996



References
  1. MPI Krypton Kr 81m Gas Generator package insert (Medi-Physics—US), Rev 7/87.
  1. Meignan M, Simonneau G, Oliveira L, et al. Computation of ventilation-perfusion ratio with Kr-81m in pulmonary embolism. J Nucl Med 1984; 25: 149-55.
  1. Chilton HM, Witcofski RL. Nuclear pharmacy—an introduction to the clinical application of radiopharmaceuticals. Philadelphia: Lea & Febiger 1986: 141-4.
  1. Rosen JM, Biello DR, Siegel BA, et al. Kr-81m ventilation imaging: Clinical utility in suspected pulmonary embolism. Radiology 1985; 154(3): 787-90.
  1. Maynard CD. Clinical nuclear medicine. 1st ed. Philadelphia: Lea & Febiger, 1971.
  1. Subramanian G, Rhodes BA, Cooper JF, Sodd VJ, editors. Radiopharmaceuticals. New York: The Society of Nuclear Medicine, Inc., 1975: 298.
  1. Chilton HM, Witcofski RL. Nuclear pharmacy—an introduction to the clinical application of radiopharmaceuticals. Philadelphia: Lea & Febiger, 1986: 141.
  1. Reviewers' responses to Radiopharmaceuticals Panel ballot of 9/88.
  1. USP Radiopharmaceuticals Advisory Panel Meeting, 5/91.
  1. Maisey MN, Britton KE, Gilday DL. Clinical nuclear medicine. 2nd ed. Philadelphia: J.B. Lippincott, 1991: 69.
  1. 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: 160.
  1. Swanson DP, Chilton HM, Thrall JH, editors. Pharmaceuticals in medical imaging. New York: Macmillan Publishing Company, 1990: 403-13.
  1. Reviewers' consensus on monograph revision of 5/29/92.
  1. Krypton Kr 81m Gas Generator package insert (Amersham—US), Rev 1/95, Rec 11/95.
Hide
(web3)