Radioiodinated Albumin (Systemic)


VA CLASSIFICATION
Primary: DX202

Commonly used brand name(s): IHSA I 125; Jeanatope; Megatope.

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



Category:


Diagnostic aid, radioactive (fluid and blood loss)—

Indications

Accepted

Blood and plasma volumes determinations—Iodinated I 125 and I 131 albumin are indicated for use in determinations of total blood and plasma volumes. {01} {03} {07} {08} {09} {10} {11}

Unaccepted
Radioiodinated albumin has been used in determinations of cardiac and pulmonary blood volumes and circulation times and of cardiac output; in protein turnover studies to help determine gastrointestinal loss of protein. Iodinated I 131 albumin has been used for the delineation of the heart and great vessels; in placenta localization for the detection of placenta previa; and in brain scanning for the localization of cerebral neoplasms. However, these agents generally have been replaced by more effective and/or safer agents for these indications. {03} {14}


Physical Properties

Nuclear data: {01} {14}



Radionuclide
(half-life)
Decay
constant
Mode
of
decay
Principal
emissions
(keV)
Mean
number of
emissions/
disintegration
I 125
(60.14 days)
0.00048
h -1
Gamma
and x-ray
emissions
Gamma
(35.0)
0.067
x-ray
(28.0)
1.40
I 131
(8.08 days)
0.00358
h -1
Beta and
gamma
emissions
Beta
(191.6)
0.90
Gamma
(364.4)
0.81


Pharmacology/Pharmacokinetics

Mechanism of action/Effect:

Human serum albumin occurs naturally as the major protein component of blood. When labeled with iodine I 125 or I 131 and given intravenously, it is distributed throughout the body similarly to the patient's serum albumin, and serves as a suitable tracer with which to determine plasma or blood volume. The radioconcentration can be quantitated in blood samples withdrawn at periodic intervals, after injection of the radioiodinated albumin. Although the gamma emissions of I 131 are suitable for external imaging, the biodistribution of iodinated I 131 albumin is seldom evaluated by in vivo imaging. {09} {10} {14}

Distribution:

Radioiodinated serum albumin—Within 10 minutes throughout intravascular pool; more slowly into extravascular space. Can also be detected in the lymph and in certain body tissues within 10 minutes after injection; maximum distribution throughout the extravascular space does not occur until 2 to 4 days following injection. {07} {09}

Radioiodine—Small amount of released iodine I 125 or iodine I 131 (resulting from degradation of radioiodinated albumin) is selectively concentrated in thyroid gland; also concentrated in choroid plexus, gastric mucosa, salivary glands, stomach, and lactating breast. {02} {14}

Radiation dosimetry:


I 125
Estimated absorbed radiation dose*
Organ
mGy/MBq
rad/mCi
Heart
0.69
2.56
Spleen
0.59
2.19
Lungs
0.57
2.11
Red marrow
0.37
1.37
Kidneys
0.33
1.22
Bone surfaces
0.32
1.19
Adrenals
0.30
1.11
Liver
0.30
1.11
Thyroid
0.26
0.96
Pancreas
0.23
0.85
Stomach wall
0.21
0.78
Small intestine
0.21
0.78
Large intestine (upper)
0.21
0.78
Large intestine (lower)
0.20
0.74
Bladder wall
0.20
0.74
Breast
0.20
0.74
Ovaries
0.20
0.74
Uterus
0.20
0.74
Testes
0.16
0.59
Other tissue
0.19
0.70
Effective dose: 0.34 mSv/MBq (1.26 rem/mCi)
* For adults; intravenous injection


I 131
Estimated absorbed radiation dose*
Organ
mGy/MBq
rad/mCi
Heart
1.9
7.03
Lungs
1.5
5.55
Spleen
1.5
5.55
Bone surfaces
0.97
3.59
Adrenals
0.94
3.59
Kidneys
0.88
3.26
Liver
0.72
2.66
Thyroid
0.70
2.59
Red marrow
0.66
2.44
Breast
0.55
2.04
Stomach wall
0.53
1.96
Small intestine
0.52
1.92
Large intestine (upper)
0.52
1.92
Uterus
0.51
1.89
Large intestine (lower)
0.50
1.85
Ovaries
0.49
1.81
Bladder wall
0.49
1.81
Testes
0.46
1.70
Other tissue
0.47
1.74
Effective dose: 0.86 mSv/MBq (3.18 rem/mCi)
* For adults; intravenous injection

Half-time:

Normal human serum albumin—Approximately 14 days (range, 10 to 20 days); dependent on initial rate of excretion, which is determined by the quality of the labeled albumin. {07} {09} {12} {14}

Elimination:
    Primarily renal; about 2% eliminated in feces. {07} {09}


Precautions to Consider

Cross-sensitivity and/or related problems

Patients sensitive to human serum albumin–containing products may be sensitive to these products also.

Pregnancy/Reproduction

Pregnancy—
Iodine I 125 and I 131 cross the placenta and may cause severe and irreversible hypothyroidism in the fetus; the fetal thyroid begins to concentrate iodine during approximately the 12th week of gestation. Radioiodinated albumin is usually not recommended for use during pregnancy; however, if used, prior administration of potassium iodide (e.g., Lugol's solution or SSKI) may reduce the risk of fetal thyroid irradiation. {01} {04} {13}

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. {05}


Radioiodinated albumin

Studies have not been done in humans with either iodinated I 131 albumin or iodinated I 125 albumin.

Studies have not been done in animals.

FDA Pregnancy Category C. {01} {07} {14}


Breast-feeding

Iodine I 125 and I 131 are distributed into breast milk. Because of the potential risk to the infant from radiation exposure, temporary discontinuation of nursing is recommended for a length of time that may be assessed by measuring the activity of breast milk and estimating the radiation exposure to the infant. {01} {03} {07} {09}

Pediatrics

Although radioiodinated albumin is used in children, there have been no specific studies evaluating its safety and efficacy in children. When this radiopharmaceutical is used in children, the diagnostic benefit should be judged to outweigh the potential risk of radiation. {05}


Geriatrics


Appropriate studies on the relationship of age to the effects of radioiodinated albumin have not been performed in the geriatric population. However, no geriatrics-specific problems have been documented to date. {11}

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 other diagnostic test results
Thyroid function determinations and
Thyroid imaging    (potassium iodide [e.g., Lugol's solution] used prior to the administration of radioiodinated albumin may cause a decrease in radioactive iodine or pertechnetate ion uptake for several weeks {07} {08} {09})


Medical considerations/Contraindications
The medical considerations/contraindications included have been selected on the basis of their potential clinical significance (reasons given in parentheses where appropriate)— not necessarily inclusive (» = major clinical significance).


Risk-benefit should be considered when the following medical problem exists
» Sensitivity to human serum albumin-containing products


Side/Adverse Effects
Presently, there are no known side/adverse effects associated with the use of iodinated I 125 or I 131 albumin as a diagnostic aid. However, as with any protein-containing preparation, allergic reactions are possible. {07} {09}



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: Radioactive albumin's distribution in body same as normal albumin

Dilution of radioactivity in blood pool permits calculation of its volume

Small amounts of radioactivity used in diagnosis; radiation received is low and considered safe

Before having this test
»   Conditions affecting use, especially:
Sensitivity to human serum albumin

Pregnancy—Risk to fetus from radiation exposure as opposed to benefit derived from use should be considered; possibility of hypothyroidism in fetus





Breast-feeding—Iodine I 125 and I 131 are distributed into breast milk; temporary discontinuation of nursing recommended because of risk to infant from radiation exposure





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
Possible interference with future thyroid tests


Side/adverse effects
No side/adverse effects reported; allergic reactions are possible


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.

Epinephrine, antihistamines, and corticosteroid agents should be available during the administration of radioiodinated albumin because of the possibility of allergic reactions.

To minimize the uptake of radioactive iodine by the thyroid, potassium iodide (e.g., Lugol's solution or SSKI) may be used one to three times daily, beginning at least 24 hours before and continuing for one or two weeks after administration of radioiodinated albumin. {04} {07} {13} {14}

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. {15}


Parenteral Dosage Forms

IODINATED I 125 ALBUMIN INJECTION USP

Usual adult and adolescent administered activity
Total blood and plasma volume determinations
Intravenous, 0.185 to 1.85 megabecquerels (5 to 50 microcuries). {09}

Note: For repeat blood volume determinations, the total dosage per week should not exceed 7.4 megabecquerels (200 microcuries). {09}
See manufacturer's package instructions for preparation of the reference solution and for formula used in the calculation of blood and plasma volumes.



Usual pediatric administered activity
Dosage must be individualized by physician. {03}

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

Size(s) usually available:
U.S.—



At time of calibration: Per single-dose syringe


0.37 megabecquerel (10 microcuries) per 1.5 mL (Rx) [IHSA I 125]



At time of calibration: Per multiple-dose vial


37 megabecquerels (1 millicurie) (Rx) [Jeanatope]

Canada—


Content information not available at present (Rx)[Generic]

Packaging and storage:
Store between 2 and 8 °C (36 and 46 °F). Protect from freezing. {09}

Note: Caution—Radioactive material.



IODINATED I 131 ALBUMIN INJECTION USP

Usual adult and adolescent administered activity
Total blood and plasma volume determinations
Intravenous, 0.185 to 1.85 megabecquerels (5 to 50 microcuries). {07}

Note: For repeat blood volume determinations, the total dosage per week should not exceed 7.4 megabecquerels (200 microcuries).
See manufacturer's package instructions for preparation of the reference solution and for formula used in the calculation of blood and plasma volumes.



Usual pediatric administered activity
Dosage must be individualized by physician. {03}

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

Size(s) usually available:
U.S.—



At time of calibration: Per multiple-dose vial


37 megabecquerels (1 millicurie) per mL (Rx) [Megatope{13}]

Canada—



At time of calibration: Per multiple-dose vial


0.185 to 0.555 megabecquerels (5 to 15 microcuries) per mL (Rx)[Generic]


3.7 to 37 megabecquerels (0.1 to 1 millicurie) per mL (Rx)[Generic]

Packaging and storage:
Store between 2 and 8 °C (36 and 46 °F). Protect from freezing. {07}

Note: Caution—Radioactive material.




Revised: 08/20/1994



References

Note: All references used in the development and earlier revisions of this monograph have not yet been incorporated into the computer database and, therefore, are not listed below. Citations for information not yet referenced in the monograph will be provided upon request.

  1. Albumotope package insert (Squibb—US), Rev 8/84.
  1. Maynard CD. Clinical nuclear medicine. Philadelphia: Lea & Febiger, 1971: 106-12, 159, 246.
  1. Reviewers' comments per revision of 3/84.
  1. Hladik WB, Saha GB, Study KT, editors. Essentials of nuclear medicine. Baltimore: Williams & Wilkins, 1987: 66, 413.
  1. USP Radiopharmaceuticals Advisory Panel meeting 5/91.
  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: 287.
  1. Megatope package insert (Iso-Tex—US), Rev 5/89.
  1. IHSA I 125 package insert (Mallinckrodt—US), Rev. 8/90.
  1. Jeanatope package insert (Iso-Tex—US), Recv. 6/92.
  1. Swanson DP, Chilton HM, Thrall JH. Pharmaceuticals in medical imaging. New York: Macmillan, 1990: 616-20.
  1. Ernest D, Hartman NG, Deane CP, et al. Reproducibility of plasma and extracellular fluid volume measurements in critically ill patients. J Nucl Med 1992; 33: 1468-71.
  1. Subramanian G, Rhodes BA, Cooper JF, et al., editors. Radiopharmaceuticals. New York: Society of Nuclear Medicine, Inc., 1975: 639.
  1. Reviewers' comments as per 9/92 revision of iodinated I 131 albumin monograph.
  1. Reviewers' comments as per 2/93 revision of Radioiodinated albumin monograph.
  1. Reviewers' responses to Ballot of 5/11/94.
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