technetium Tc 99m albumin aggregated injection (Rx)

Contraindications

Severe pulmonary hypertension

Hypersensitivity to products containing human serum albumin

Cautions

Deaths have been reported in patients with severe pulmonary hypertension after the administration of technetium Tc 99m albumin aggregated products; assess patients for history or signs of pulmonary hypertension; administer the lowest number of particles possible, have emergency resuscitation equipment available, and monitor patients for adverse reactions

Serious reactions have been reported; obtain a history of allergy or hypersensitivity reactions and always have emergency resuscitation equipment and trained personnel available before administration; monitor for hypersensitivity reactions

In patients with right-to-left heart shunts, risk for temporary mechanical impediment to blood flow may exist due to rapid entry of aggregated albumin into systemic circulation; administer lowest possible number of particles of Technetium Tc 99m Albumin Aggregated Injection in these patients

Radiation risk

• Technetium Tc 99m albumin aggregated contributes to a patient’s overall long-term cumulative radiation exposure; long-term cumulative radiation exposure is associated with increased risk for cancer
• Contents of Pulmotech MAA vials are not radioactive
• However, after adding sodium pertechnetate Tc 99m injection solution to the vial, maintain adequate shielding of the final preparation
• As in the use of any radioactive material, ensure to minimize radiation exposure to the patient and to occupational workers
• Advise patients to hydrate before and after administration and to void frequently after administration
• Radiopharmaceuticals should be used only by qualified and trained physicians who are experienced in the safe use and handling of radionuclides

Pregnancy

Available data from case reports are insufficient to evaluate drug-associated risks of major birth defects, miscarriage, or adverse maternal or fetal outcomes

All radiopharmaceuticals have the potential to cause fetal harm, depending on the fetal stage of development and the magnitude of the radiation dose

Advise patients about the potential for adverse pregnancy outcomes based on the radiation dose and the gestational timing of exposure

Lactation

Data available in the published literature demonstrate the presence of pertechnetate in human milk

No data available on the effects of Tc-99m albumin aggregated injection on the breastfed infant or the effects on milk production

Temporary discontinuation of breastfeeding may minimize exposure of pertechnetate to a breastfed infant

Clinical considerations

• To decrease radiation exposure to the breastfed infant, advise a lactating woman to pump and discard breast milk after the administration for 13 hours, where the duration corresponds to the typical range of administered activity, 37-148 MBq (1-4 mCi)
• During the period of interruption, empty the breasts regularly and completely; discard any pumped milk by the mother
• Refrigerate or give the pumped milk to the infant after 10 physical half-lives, or about 60 hr, have elapsed

Pregnancy Categories

A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

NA: Information not available.

Mechanism of Action

Within 1-5 minutes of IV injection, over 90% of the technetium Tc 99m albumin aggregated particles are trapped in the arterioles and capillaries of the lung

Following intraperitoneal administration, the radiopharmaceutical mixes with the peritoneal fluid; clearance from the peritoneal cavity varies from insignificant, which may occur with complete shunt blockage, to very rapid clearance with subsequent transfer into the systemic circulation when the shunt is patent

Distribution

Organ selectivity is a direct result of particle size

At ≤10 microns, albumin aggregates are taken up by the reticuloendothelial system

>10-15 microns, the aggregates become lodged in the lung capillaries by a purely mechanical process

Distribution of aggregated albumin in the lungs is a function of regional pulmonary blood flow

Elimination

Half-life: 10.8 hr

Precautions

Perform all transfer and vial stopper entries using aseptic techniques.

Wear waterproof gloves during entire preparation procedure and during subsequent patient dose withdrawals from vial

Make all transfers of sodium pertechnetate Tc 99m injection solution during the preparation procedure with an adequately shielded syringe.

Make all withdrawals and injections of radioactive preparation with an adequately shielded syringe

Preparation of Technetium Tc 99m Albumin Aggregated

Remove vial from refrigerator and allow vial to come to room temperature for ~5 min; calculate the amount of sodium pertechnetate Tc 99m injection solution (2-13 mL) to be added to the Pulmotech MAA vial

Ensure the radioactive dose contains the desired number of MAA particles when choosing the amount of technetium Tc 99m radioactivity to be used in the preparation of technetium Tc 99m albumin aggregated particles; also, take into account the number of patients, administered radioactive dose, and radioactive decay

Recommended maximum amount of technetium Tc 99m to be added to the Pulmotech vial is 6.85 GBq (185 mCi)

Calculate the amount of radioactivity per vial required to be added to maintain the number of particles per dose within a recommended range

After adding sodium pertechnetate Tc 99m injection solution to the Pulmotech MAA vial in the dispensing vial shield (with cap in place), mix contents by agitation and allow to stand for at least 15 min at room temperature; once prepared, product appears turbid white

Before withdrawing a dose, gently agitate the contents of the radiolabeled Pulmotech MAA vial to resuspend any settled technetium Tc 99m albumin aggregated particles

Failure to adequately mix the vial contents before use may result in a nonhomogenous suspension, resulting in a nonuniform distribution of radioactivity in the lung

Do not vent the vials; vials contain nitrogen to prevent oxidation of the complex

If repeated withdrawals are necessary, do not replace the contents with air

Administration

Advise patients to drink a sufficient amount of water to ensure adequate hydration and urge them to drink and urinate as often as possible during the first hours following administration in order to reduce radiation exposure

Visually inspect for particulate matter and discoloration before administration

Measure dose by a suitable radioactivity calibration system immediately

Gently invert to mix vial contents just before withdrawing a patient dose

Mix the syringe content just before injection

If blood is drawn into the syringe, any unnecessary delay before injection may lead to clot formation

For optimal results and because of rapid lung clearance of the radiopharmaceutical, position the patient under the imaging apparatus before administration

Slow injection is recommended; begin lung imaging immediately after administration

Owing to high kidney uptake, imaging later than 30 min after administration yields poor results

Storage

Pulmotech MAA kit: Store at 2-25ºC (36-77°F)

Prepared radiolabeled Pulmotech MAA with sodium pertechnetate Tc 99m injection: Refrigerate at 2-8ºC (36-46ºF) for up to 18 hr from the time of preparation; discard unused product