Technetium Tc 99m Mebrofenin

As a radioactive diagnostic agent, Technetium Tc 99m Mebrofenin is used with an imaging scanner to create a 3D view of the liver, gallbladder and bile duct to ensure they are functioning properly.

Overview

Technetium Tc 99m Mebrofenin is a radiopharmaceutical drug which contains a radioactive agent that is injected into the body to help doctors study the function of the body's various organs. Technetium Tc 99m Mebrofenin is specifically used to view the function of the liver, gallbladder and bile duct.

Technetium Tc 99m Mebrofenin must be administered under direct supervision of a doctor that has been specially trained in administering nuclear medicine. The drug is injected, intravenously, in the bloodstream where it can be tracked by a Positron emission tomography (PET) system.

PET is a nuclear imaging technology that detects pairs of gamma rays emitted by a positron-emitting radionuclide such as Technetium Tc 99m Mebrofenin. PET systems use sensitive panels to capture gamma ray emissions from inside the body to create a 3D image which can then be viewed by a doctor or PET technician.

Conditions treated:

  • Used to create a 3D view of the liver, gallbladder and bile duct.

Type of medicine:

  • Radioactive diagnostic agent

Side effects:

Patients taking Technetium Tc 99m Mebrofenin may in rare circumstances suffer an adverse reaction to the drug. Patients should tell their doctor immediately if they start to show signs of the following symptoms:

  • Urticaria (hives, wheals, skin rashes)
  • Chills
  • Nausea
  • Redness of the skin

Some side effects of Technetium Tc 99m Mebrofenin may not have been reported, so patients should always tell their doctor if they start to feel unwell during the course of treatment. Possible reactions should also be reported to the Food & Drug Administration (FDA) at 1-800-FDA-1088.

Dosage:

Technetium Tc 99m Mebrofenin is injected intravenously into a vein and should only administered by a doctor who has been trained in administering nuclear medicine and authorized by the Nuclear Regulatory Commission (NRC). Such nuclear medicine radiologists are specialist physicians that are trained to use radioactive materials to diagnose and treat a range of diseases.

Technetium Tc 99m Mebrofenin will need to be prepared by a nuclear pharmacist that specializes in preparing, dispensing and distributing radiopharmaceuticals. Such pharmacists will form part of the consultation team and will advise on health and safety issues during administration.

A nuclear medicine technologist may also be present during the process, whose job is to perform imaging procedures, enhance images developed during the PET process and analyze biological specimens once the procedure is complete.

Administration of Technetium Tc 99m Mebrofenin typically takes place for at least five days prior to PET imaging with dosage usually administered in two separate injections. The exact dosage will be determined by the consultation team but is usually 5 mg per kg of body weight. Fasting for at least 2 hours and preferably 4 hours is recommended before PET imaging to prevent gallbladder contraction due to the ingestion of food.

Moderate drug interactions:

Technetium Tc 99m Mebrofenin is a relatively safe drug so long as it is administered by a professional. However it is known to moderately interact with a number of other medicines, both prescribed and over the counter, so physicians will need to make sure that the patient is not taking one of the 127 known drug interactions.

The following is a list of popular medicines that are known to have moderate interactions with Technetium Tc 99m Mebrofenin:

  • Codeine
  • Morphine
  • Alfentanil
  • Propoxyphene
  • Hydrocodone
  • Phenylephrine
  • Hydrocodone

The above list is far from complete so it is important that physicians check for all possible interactions before administering Technetium Tc 99m Mebrofenin.

The following drugs may also inhibit the flow of Technetium Tc 99m Mebrofenin through the body:

  • Alcohol
  • Anticcholinergics
  • Bethanechol
  • Somatostatin (Slows gallbladder emptying, delaying the clearance of Technetium Tc 99m Mebrofenin.)
  • Erythromycin (May cause the gallbladder to become nonvisualized due to hepatotoxicity.)
  • Nicotinic acid (High-dose nicotinic acid therapy causes poor extraction and elimination of the radiopharmaceutical, giving the effect of hepatocellular disease.)

Delivery to the small bowel may also be impeded by opioid analgesics due to constriction of the sphincter of Oddi and greater biliary tract pressure, resulting in delayed visualization on the PET scan.

Warnings:

Physicians need to take a number of precautions before administering Technetium Tc 99m Mebrofenin. The patient should also be monitored throughout the process to ensure it is safe to continue treatment, with treatment reduced or stopped if complications arise.

Precautions to consider include:

Cross-sensitivity and/or related problems – Patients who are sensitive to amide-type local anesthetics may also be sensitive to Technetium Tc 99m Mebrofenin.

Carcinogenic/mutagenicity – Animal tests have not been carried out to evaluate the carcinogenic or mutagenic potential of Technetium Tc 99m Mebrofenin. Physicians should therefore proceed with caution with patients who are at risk of developing cancer.

Pregnancy – Studies of Tc 99m in animals have shown that it crosses the placenta during pregnancy. Separate studies in humans have not been carried out, so physicians need to carefully evaluate patients of childbearing age.

Patients who are pregnant should be assessed before treatment. In some cases it may be determined that the benefit of radiopharmaceutical use, outweighs the risk of radiation exposure
to the fetus. In such situations the physician should reduce the amount of medicine administered to the lowest possible amount.

Breastfeeding – Tests on whether Technetium Tc 99m Mebrofenin passes into breast milk have not been carried out, but it is known that Tc 99m is distributed into breast milk. Physicians should therefore work on the assumption that Technetium Tc 99m Mebrofenin is passed into the breast milk of nursing mothers. A guideline has therefore been proposed that is based on the effective half-life of the radionuclide in breast milk.

According to this guideline, nursing can be safely resumed when the concentration in breast milk reaches 30.3 × 10 -4 megabecquerels (8.2 × 10 -2 microcuries) per mL. In the majority of patients this level is reached within 12 to 24 hours after administration of Technetium Tc 99m Mebrofenin.

Pediatrics – No studies performed to date have suggested that Technetium Tc 99m Mebrofenin is unsafe for use in children. However, no specific studies have taken place to evaluate the safety and risks of using radiopharmaceutical drugs on pediatrics. So physicians should weigh the diagnostic benefit against the possible risk of radiation in children.

Geriatrics – Specific studies have not been carried out to establish the effect of Technetium Tc 99m Mebrofenin on the geriatric population. However, to date no geriatric-specific problems have been reported.

Warnings: Existing medical problems or conditions

  • Prolonged or acute Pancreatitis – may give give false-positive results or result in nonvisualization or delayed visualization of the gallbladder due to stasis of bile in the gallbladder.
  • Hepatocellular disease – may cause nonvisualization or delayed visualization of the gallbladder.
  • Postprandial state – the ingestion of a fatty meal immediately before the administration of Technetium Tc 99m Mebrofenin may give false-positive results due to gallbladder contraction stimulated by meal ingestion. Patients are advised to fast for up to 4 hours before PET imaging.

Storage

Technetium Tc 99m Mebrofenin is a radioactive material which should be stored in a controlled environment. The ideal storage temperature is between 15°C and 30°C (59°F to 86°F), unless otherwise specified by the manufacturer.

Technetium Tc 99m Mebrofenin should only be prepared by a registered nuclear pharmacist that specializes in preparing, dispensing and distributing radiopharmaceuticals. Prior to injection, an oxidant-free sodium pertechnetate Tc 99m solution should be created for labeling.

Warning: Injection should be administered within 18 hours of preparation.

Note: Caution–Radioactive material.

Summary

Technetium Tc 99m Mebrofenin is a radioactive diagnostic agent that is composed of the iminodiacetic acid derivative mebrofenin, which is bound to an isotope of technetium (Tc). Once administered to the bloodstream, technetium Tc 99m mebrofenin is secreted into the hepatobiliary system, where it emits gamma rays that can be detected by a positron emission tomography (PET) system.

The gamma rays collected by the PET system are then used to create a 3D model of the hepatobiliary system, allowing doctors to check that the liver, gallbladder and bile duct are all functioning correctly. If administered at the recommended dosage, Technetium Tc 99m Mebrofenin has no other pharmacological effect on the body, other than to allow the hepatobiliary system to be modeled in 3D.

Being a radioactive diagnostic agent, Technetium Tc 99m Mebrofenin must be administered by a Nuclear Regulatory Commission (NRC) registered practitioner. These are physicians that have undertaken a further 4 years training, on top of their medical training, to enable them to administer radioactive compounds to diagnose and treat a range of diseases.

So long as Technetium Tc 99m Mebrofenin is administered at the correct dosage the list of potential side effects is quite small. While there are a number of drug interactions most of these inhibit the effectiveness of the drug without causing further pain or discomfort to the patient. However, care must be taken to ensure the patient does not have a preexisting condition such as pancreatitis which could provide false-positive readings.

Care should also be taken to ensure that patients of childbearing age are not pregnant before administering the drug. Patients who are already pregnant may still be given the drug in reduced dosages, if the benefit of radiopharmaceutical use, is deemed to outweigh the risk of radiation exposure to the fetus. Patients who are breastfeeding will need to take advice from their doctor as to when nursing can be safely resumed following treatment.

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Last Reviewed:
December 25, 2017
Last Updated:
December 22, 2017
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