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Technetium Tc 99m (Pyro- and trimeta- Phosphates Systemic )


VA CLASSIFICATION
Primary: DX201

Commonly used brand name(s): Pyrolite.


Note: This monograph includes information that applies to both technetium Tc 99m (pyro- and trimeta-) phosphates and to sodium (pyro- and trimeta-) phosphates without Tc 99m label.

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



Category:


Diagnostic aid, radioactive (bone disease; cardiac disease; gastrointestinal bleeding [without Tc 99m label])—

Indications

Accepted

For technetium Tc 99m (pyro- and trimeta-) phosphates
Skeletal imaging, radionuclide—Technetium Tc 99m (pyro- and trimeta-) phosphates injection is indicated as a skeletal imaging agent to delineate areas of altered osteogenesis, such as those that occur with metastatic bone disease, Paget's disease, arthritic disease, osteomyelitis, and fractures. {01}

Cardiac imaging, radionuclide—Technetium Tc 99m (pyro- and trimeta-) phosphates injection is indicated as a cardiac imaging agent to aid in the diagnosis of acute myocardial infarction. {01}

For sodium (pyro- and trimeta-) phosphates without Tc 99m label
Red blood cells, labeling of—Intravenous injection of the unlabeled sodium (pyro- and trimeta-) phosphates component of the kit, when followed by the injection of sodium pertechnetate Tc 99m, is indicated for in vivo or modified in vitro/in vivo labeling of red blood cells. Red blood cells labeled with sodium pertechnetate Tc 99m are used for blood pool imaging in the following diagnostic studies:

• Cardiac blood pool imaging, radionuclide: To detect pericardial effusion, intracardiac abnormalities, or ventricular aneurysms. {01}


• Bleeding, gastrointestinal (diagnosis): To evaluate patients suspected of gastrointestinal bleeding, to detect the site of bleeding.



Physical Properties

Nuclear data:



Radionuclide
(half-life)
Decay
constant
Mode
of
decay
Principal
photons
(keV)
Mean
number of
photons/
disintegration
(³0.01)
Tc 99m
(6.0 hr)
0.1151 h -1
Isomeric
transition to
Tc 99
18
0.062
140.5
0.891


Pharmacology/Pharmacokinetics

Physicochemical characteristics:
Molecular weight—
    Sodium pyrophosphate: 265.90
    Sodium trimetaphosphate: 305.89
    Stannous chloride: 225.63

Mechanism of action/Effect:


Skeletal and cardiac imaging:

Exact mechanism is unknown. Technetium Tc 99m (pyro- and trimeta-) phosphates" affinity for hydroxyapatite crystals, found in bone and within infarcted myocardial cells, may be responsible for its skeletal and myocardial uptake, with blood flow and/or blood concentration being most important in the delivery of the phosphate complex for uptake. Since normal myocardial tissue does not appreciably accumulate the phosphate complex, an area of acute damage will appear as a focus of increased activity. {05}Visualization of osseous lesions also is possible since skeletal uptake of technetium Tc 99m (pyro- and trimeta-) phosphates is altered in areas of abnormal osteogenesis.



Red blood cells, labeling of:

When used for cardiac blood pool imaging or to detect gastrointestinal bleeding, pretreatment with the stannous ion–containing phosphate complex causes the technetium Tc 99m (as sodium pertechnetate Tc 99m) to bind to the red blood cells in vivo, with about 75–85% of the injected radioactivity remaining in the blood pool long enough to provide images of the cardiac chambers or sites of active (rapid) or cumulative (intermittent) gastrointestinal bleeding. Modified in vitro/in vivo method of labeling red blood cells usually results in a greater percent of the injected radioactivity remaining in the blood pool. {01} {02} {07}


Distribution:

Technetium Tc 99m (pyro- and trimeta-) phosphates is selectively concentrated in areas of altered osteogenesis and injured myocardium with minimal uptake by soft-tissue organs, with the exception of the kidneys.

Radiation dosimetry:
{01}

Mode of
administra-
tion
Radiation
source
(% administered
activity)
Estimated absorbed radiation dose
Target organ
mGy/
MBq
rad/mCi
Intravenous
Technetium
Tc 99m
(Pyro- and
trimeta-)
Phosphates Technetium Tc 99m (pyro- and trimeta-) phosphates*
Skeleton
(50%)
Urinary
bladder
(50%)
Bladder
   
  2 hr void
0.026
0.097
  4.8 hr void
0.062
0.230
Skeleton
0.014
0.054
Kidneys
0.013
0.047
Bone marrow
0.010
0.038
Testes
   
  2 hr void
0.003
0.010
  4.8 hr void
0.004
0.015
Heart
   
  Normal
0.002
0.009
  Impaired
0.004
0.015
Ovaries
   
  2 hr void
0.002
0.009
  4.8 hr void
0.004
0.015
Red marrow
0.006
0.022
Total body
0.004
0.015
Intravenous
Sodium
Pertechne-
tate
Tc 99m Technetium Tc 99m (pyro- and trimeta-) phosphates
  Bladder wall
0.032
0.120
  Blood
0.014
0.052
  Ovaries
0.006
0.023
  Spleen
0.005
0.018
  Testes
0.003
0.012
  Total body
0.004
0.015
* For skeletal and cardiac imaging.
 For blood pool imaging. Preceded by intravenous administration of unlabeled sodium (pyro- and trimeta-) phosphates.

Elimination:
    Renal; up to 50% of the dose of technetium Tc 99m (pyro- and trimeta-) phosphates eliminated within the first 3 to 6 hours. {01}


Precautions to Consider

Carcinogenicity/Mutagenicity

Long-term animal studies to evaluate carcinogenic or mutagenic potential of technetium Tc 99m (pyro- and trimeta-) phosphates have not been performed.

Pregnancy/Reproduction

Pregnancy—
Tc 99m (as free pertechnetate) crosses the placenta. However, studies have not been done in either animals or humans with technetium Tc 99m (pyro- and trimeta-) phosphates.

Radiopharmaceuticals are usually not recommended during pregnancy because of the risk to the fetus from radiation exposure.

To avoid the possibility of fetal exposure to radiation, in those circumstances where the patient's pregnancy status is uncertain, a pregnancy test will help to prevent inadvertent administration of this preparation during pregnancy. {01} {15}

FDA Pregnancy Category C.

Breast-feeding

Although it is not known whether technetium Tc 99m (pyro- and trimeta-) phosphates is excreted in breast milk, it is known that Tc 99m as free pertechnetate is excreted in breast milk. Based on the assumption that the Tc 99m in breast milk is in the form of pertechnetate and based on the effective half-life of the radionuclide in breast milk, the daily volume of milk, a dose factor relating the radionuclide to its critical organ (thyroid) in the nursing infant, and the maximum permissible dose to that organ, a guideline has been proposed. According to this guideline, it has been calculated that nursing can be safely resumed when the concentration in breast milk reaches 30.3 × 10 -4 megabecquerels (8.2 × 10 -2 microcuries) per mL. This level of activity is probably reached, in the majority of patients, within 24 hours after administration of 740 megabecquerels (20 millicuries) of technetium Tc 99m. {15}

Pediatrics

Diagnostic studies performed to date using technetium Tc 99m–labeled red blood cells have not demonstrated pediatrics-specific problems that would limit the usefulness of technetium Tc 99m (pyro- and trimeta-) phosphates in children. However, because of the potential risk of radiation exposure, risk-benefit must be considered. {09} {11}


Geriatrics


Although appropriate studies have not been performed in the geriatric population, no geriatrics-specific problems have been documented to date. {10}

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 blood pool imaging (cardiac blood pool imaging and diagnosis of gastrointestinal bleeding)

Due to other medications
Digoxin or
Doxorubicin or
Heparin sodium or
Hydralazine or
Methyldopa or
Prazosin or
Propranolol or
Quinidine or
Radiopaques, water-soluble organic iodides, with intravascular administration{05}    (concurrent use with these medications may impair blood pool images because of a decrease in labeling of red blood cells {01} {05})


Due to medical problems or conditions
Goiter, toxic diffuse or
Hyperthyroidism    (thyroid uptake may be increased {05})


Lupus erythematosus    (labeling of red blood cells may be decreased {05})


Transfusion-induced reaction    (labeling efficiency may be decreased because of red blood cell antibody formation {05})

With results of cardiac imaging

Due to other medications
Antacids, aluminum-containing    (high blood concentrations of aluminum ion, which may occur in patients with gastrointestinal obstruction or impaired renal function, may cause localization of technetium Tc 99m [pyro- and trimeta-] phosphates in the liver and spleen {01} {05} {08})


Estrogens    (possible localization of technetium Tc 99m [pyro- and trimeta-] phosphates in breast {01} {05} {08})


Heparin sodium    (diffuse uptake of technetium Tc 99m [pyro- and trimeta-] phosphates into the myocardium, with signs of diminished uptake into the infarct {08})


Methylprednisolone    (methylprednisolone may increase glomerular filtration rate and excretion of technetium Tc 99m [pyro- and trimeta-] phosphates, resulting in faster blood clearance of the radiotracer, and thus decreasing myocardial uptake of the radiotracer {01} {05} {08})


Radiation therapy    (diffuse myocardial uptake of technetium Tc 99m [pyro- and trimeta-] phosphates {01} {05} {08} {09})


Verapamil    (patchy liver uptake of technetium Tc 99m [pyro- and trimeta-] phosphates may result due to hepatocellular damage caused by verapamil toxicity {01} {05} {06})


Due to medical problems or conditions
Amyloidosis or
Hyperphosphatemia or
Sarcoidosis, myocardial    (diffuse cardiac uptake may occur {05})


Angina pectoris, unstable or
Cardiac contusions or
Coronary bypass surgery, recent or
Myocardial infarcts, previous    (false-positive cardiac images may occur {01})


Gynecomastia, estrogen-induced or
Lactation    (possible localization of technetium Tc 99m [pyro- and trimeta-] phosphates in breast {05})


Hepatic necrosis, massive    (possible liver uptake of technetium Tc 99m [pyro- and trimeta-] phosphates {05})


Myocardial infarcts, time of    (false-negative cardiac images may occur in the diagnosis of acute myocardial infarction if test is performed too early in the evolutionary phase or too late in the resolution phase of the infarct {01})

With results of skeletal imaging

Due to other medications
Antacids, aluminum-containing    (high blood concentrations of aluminum ion, which may occur in patients with gastrointestinal obstruction or impaired renal function, may cause localization of technetium Tc 99m [pyro- and trimeta-] phosphates in the liver {01} {05} {06})


Amphotericin B or
Antineoplastics    (biodistribution of technetium Tc 99m [pyro- and trimeta-] phosphates may be altered with concurrent administration of these medications {01} {05} {06})


Diatrizoate sodium    (possible renal and hepatic uptake of technetium Tc 99m [pyro- and trimeta-] phosphates if diatrizoate sodium is administered intravenously immediately after technetium Tc 99m [pyro- and trimeta-] phosphates {01} {05} {06})


Etidronate    (etidronate may theoretically interfere with bone uptake of technetium Tc 99m [pyro- and trimeta-] phosphates; clinical significance is unknown {01} {05} {06} {12})


Heparin calcium, subcutaneous or
Radiation therapy    (concurrent administration may result in extraosseous accumulation of technetium Tc 99m [pyro- and trimeta-] phosphates {01} {05} {06})


Iron dextran, intramuscular or
Meperidine, intramuscular    (possible accumulation of technetium Tc 99m [pyro- and trimeta-] phosphates at site of injection {01} {05} {06})


Iron supplements or preparations    (iron overload may cause a decrease in bone uptake {01} {05} {06})


Potassium phosphates or
Potassium and sodium phosphates or
Sodium phosphates    (saturation of bone binding sites by phosphorous ions in these medications may cause decreased bone uptake {01} {05} {06})


Due to medical problems or conditions
Amyloidosis or
Carcinomas or
Cirrhosis or
Diabetes mellitus or
Hypercalcemia    (biodistribution of technetium Tc 99m [pyro- and trimeta-] phosphates may be altered, resulting in an increased uptake by other organs {01} {05})


Blood transfusions, repeated    (may cause a decrease in bone uptake {01} {05})


Bone demineralization, adrenocorticoid (glucocorticoid)-induced    (long-term therapy with these medications may induce bone mineral depletion, thus causing decreased bone uptake of technetium Tc 99m [pyro- and trimeta-] phosphates {01} {05} {09})


Gynecomastia, estrogen-induced or
Lactation    (possible localization of technetium Tc 99m [pyro- and trimeta-] phosphates in breast {01} {05} {06})


Obesity    (attenuation of photons coming from bone may decrease visualization {01} {05})


Osteoporosis    (reduced mineral deposits in bone may result in images with lower target to non-target ratio {01} {05})


Renal function impairment    (decreased drug clearance from blood and soft tissues may decrease visualization because of a lower bone-to-background ratio resulting from the increased circulating activity; also, chronic renal function impairment may cause metastatic calcification and altered biodistribution of technetium Tc 99m [pyro- and trimeta-] phosphates {01} {05})

With other diagnostic test results
Brain scan using sodium pertechnetate Tc 99m    (may give either false-positive or false-negative results when performed after a bone scan using technetium Tc 99m [pyro- and trimeta-] phosphates because of its stannous ion content; to avoid false results, brain scan should be performed prior to bone scan or with a brain imaging agent other than sodium pertechnetate Tc 99m)


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).

See also Diagnostic interference.

Risk-benefit should be considered when the following medical problem exists
Sensitivity to the radiopharmaceutical preparation


Side/Adverse Effects
The following side/adverse effects have been selected on the basis of their potential clinical significance (possible signs and symptoms in parentheses where appropriate)—not necessarily inclusive:

Those indicating need for medical attention
Incidence less frequent or rare
    
Allergic reaction {01}(skin rash, hives, or itching)





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 bone and cardiac tissues and in labeled red blood cells

Retention of radioactivity allows visualization of skeletal or cardiac lesions, or visualization of blood pool

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

Before having this test
»   Conditions affecting use, especially:
Sensitivity to the radiopharmaceutical preparation

Pregnancy—Technetium Tc 99m (as free pertechnetate) crosses placenta; risk to fetus from radiation exposure





Breast-feeding—Not known if excreted in breast milk; temporary discontinuation of nursing may be recommended because of risk to infant from radiation exposure





Use in children—Risk of radiation exposure


Preparation for this test
Special preparatory instructions may be given; patient should inquire in advance

For cardiac and skeletal imaging: Increasing intake of fluids and voiding frequently after injection and before test begins to minimize radiation exposure to bladder; voiding again just prior to imaging for best test results

Precautions after having this test
For cardiac and skeletal imaging: Increasing intake of fluids and voiding frequently for 4 to 6 hours after test to minimize radiation exposure to bladder


Side/adverse effects
Signs of potential side effects, especially allergic reaction


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 radionuclides and who are licensed by the Nuclear Regulatory Commission (NRC) or the appropriate Agreement State agency or, outside the U.S., the appropriate authority.

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

For cardiac and skeletal imaging
Unless cardiac status indicates otherwise, the patient should increase intake of fluids and void frequently following the administration of technetium Tc 99m (pyro- and trimeta-) phosphates injection, and for 4 to 6 hours after the imaging procedures are completed, to minimize radiation exposure to the bladder. {01}

Voiding is also recommended immediately prior to imaging procedures to reduce background interference that may result from accumulation of the agent in the bladder. {13}

For blood pool imaging (cardiac blood pool imaging and diagnosis of gastrointestinal bleeding)
Unlabeled sodium (pyro- and trimeta-) phosphates should be injected by direct venipuncture. Heparinized catheter systems should not be used. {01}

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. {14}


Parenteral Dosage Forms

TECHNETIUM Tc 99m (PYRO- AND TRIMETA-) PHOSPHATES INJECTION USP

Usual adult and adolescent administered activity


For technetium Tc 99m (pyro- and trimeta-) phosphates:
Skeletal imaging—Intravenous, 555 to 925 megabecquerels (15 to 25 millicuries).

Cardiac imaging—Intravenous, 740 to 1295 megabecquerels (20 to 35 millicuries).



For sodium (pyro- and trimeta-) phosphates without Tc 99m label:
Blood pool imaging—Intravenous, 14 to 42 mg of sodium (pyro- and trimeta-) phosphates (unlabeled) followed, by the intravenous administration of 185 to 740 megabecquerels (5 to 20 millicuries) of sodium pertechnetate Tc 99m five to thirty minutes later. {01}


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.—


10 mg of sodium pyrophosphate, 30 mg of sodium trimetaphosphate, 0.95 mg (minimum) of stannous chloride, and 1.8 mg (maximum) total tin, per reaction vial (Rx) [Pyrolite]

Canada—


10 mg of sodium pyrophosphate, 30 mg of sodium trimetaphosphate, 0.95 mg (minimum) of stannous chloride, and 1.8 mg (maximum) total tin, per reaction vial (Rx) [Pyrolite]

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

Preparation of dosage form:
To prepare technetium Tc 99m (pyro- and trimeta-) phosphates injection, an oxidant-free sodium pertechnetate Tc 99m solution is used. See manufacturer's package insert for complete instructions.

To prepare sodium (pyro- and trimeta-) phosphates injection (unlabeled), 3 to 4 mL of sterile sodium chloride injection is used. See manufacturer's package insert for complete instructions.

Stability:
Technetium Tc 99m (pyro- and trimeta-) phosphates injection should be administered within 6 hours after preparation.

Sodium (pyro- and trimeta-) phosphates injection (unlabeled) should be administered within 6 hours after preparation. {01}

Incompatibilities:
If oxidants such as peroxides and hypochlorites are present in the sodium pertechnetate Tc 99m used for labeling, the final preparation of Technetium Tc 99m (pyro- and trimeta-) phosphates injection may be adversely affected and should be discarded. {01}

Note: Caution—Radioactive material.




Revised: 08/02/1994



References
  1. Pyrolite package insert.
  1. Chilton, Witcofski. Nuclear pharmacy—an introduction to the clinical application of radiopharmaceuticals. Lea & Febiger, 1986, p 122-3.
  1. USAN.
  1. MIRD Pamphlet No. 10.
  1. Shaw SM. Drugs and diseases that may alter the biodistribution or pharmacokinetics of radiopharmaceuticals. Pharmacy Int'l, Dec. 1985, pp 293-8.
  1. Hladik et al. Drug-induced changes in biodistribution—Seminars in Nuclear Medicine, April 1982, p 194-6.
  1. Dis. Col. & Rect., Jan. 1984, pp 47-52.
  1. Laven DL, Clanton JA, Hladik WB, et al. Pharmacologic alterations in the biorouting/performance of select radiopharmaceuticals used in cardiac imaging. Monograph presented at SNM Annual Meeting 6/90.
  1. Hladik WB, Saha GB, Study KT. Essentials of nuclear medicine science. Williams & Wilkins, 1987; pp 57, 193-7.
  1. Goldstein SA, Lindsay J, Chandeysson PL, et al. Usefulness of technetium pyrophosphate scintigraphy in demonstrating cardia amyloidosis in persons aged 85 years and older. Am J Cardiol 1988; 63: 752.
  1. Parrish M, Graham TP. Radionuclide angiography in children. J of Pediatrics 1984; 104(2): 165–71.
  1. Norwich Eaton comment 8/87 in Etidronate (Systemic), USP-DI.
  1. Technetium Tc 99m pyrophosphate monograph in USP-DI.
  1. Reviewers' responses to Ballot of 5/11/94.
  1. Panel 1/88 Meeting.
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