What Are Radiopharmaceuticals?

PET scans detect the internal movement of radioactive drugs that have been introduced to a body.
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  • Written By: Brenda Scott
  • Edited By: Bronwyn Harris
  • Last Modified Date: 19 March 2014
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Pharmaceuticals are substances used to diagnose, treat or prevent disease. Radiopharmaceuticals are radioactive substances used in nuclear medicine. These drugs are made up of two components: a radioactive isotope that can be injected safely into the body, and a carrier molecule which delivers the isotope to the area to be treated or examined.

One popular nuclear ingredient is an isotope called technetium (Tc), the lightest radioactive element known, which is used in a variety of nuclear tests. Thallium-201 is used for cardiac stress tests. Other common nuclear components used include indium-111, gallium-67, iodine-123, iodine-131 and venom-133.

The majority of nuclear medicine involves diagnostic testing. When radiopharmaceuticals are injected into the body, they emit radiation that can be traced with special cameras or computers. The amount of radiation a patient is subjected to is about the same as a normal X-ray, but the information gathered is significantly different. Non-nuclear diagnostic methods, such as X-rays and ultrasounds, show the size and shape of a bone, organ or tumor. Nuclear medicine allows a medical professional to see how an organ is functioning.

Once radiopharmaceuticals enter the body and travel to an organ, they begin to interact with the processes of that organ. The radioactivity is picked up by cameras or computers and used to map the process. For example, an ultrasound can show an image of an organ and reveal if a tumor or other abnormality is present. Nuclear medicine can show how the process of glucose metabolism is functioning in the organ.


Nuclear diagnostic testing can be performed on almost every organ of the body. There are currently over 100 nuclear medical exams, with more being developed. Some of these include brain scans, bone scans, cardiac stress tests and thyroid studies. Prior to the test, the radiopharmaceutical is administered to the patient orally, intravenously, or by inhalation. The radioactive material is short-lived, and either converts to a non-radioactive substance, or passes quickly through the body.

Two of the most commonly used pieces of nuclear imaging equipment are the PET and SPECT scans. Positron emission tomography (PET) scans use cameras and computers to construct three-dimensional images of the area being examined. The single photon emission computerized tomography (SPECT) scan creates cross-sectional images of an area. The SPECT scan emits gamma rays, while the PET scan emits photons which convert to gamma rays.

The radiation in these drugs does not harm cells growing at a normal rate, but it can destroy fast growing cells. Since most cancer cells grow very rapidly, radiation treatment is frequently used to destroy cancerous tumors. Radioactive iodine (I-131) capsules are administered to treat some types of thyroid cancer. A drug called Quadramet® is given intravenously to relieve pain caused by bone cancer.

The use of radiopharmaceuticals is expected to increase rapidly as new diagnostic methods are developed. Nuclear medicine is being considered for use in infection imaging, neurology and other fields. At this time, most therapeutic substances involve the treatment of cancer. On-going research is being conducted to expand nuclear medicines to treat other diseases as well.


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Post 6

This is a very interesting topic since we are now moving to the 21st century and many kinds of diseases are also evolving and this a welcome news to treatments of more dangerous kinds of diseases. My concern is how are these substances manufactured and what government agency is regulating these drugs, or are they considered as drugs?

Post 5

This field is not in the beginning phase. It's been around since Madame Curie discovered isotopes. There are many reactors world wide making them, and they are used often. I've been in the field for 60 years.

Post 3

@turkay1-- I read about this. Radiopharmaceuticals are made in radioactive reactors. They cannot be dealt with any other setting anyway.

I think for the most part, there are not many concerns with their production in these facilities as long as the producer follows the safety regulations and checks the quality of the radioactive product after.

This field can still be considered in the beginning stages, so there may be additional regulations applied to it as more and more facilities start producing them. I don't think that there are many reactors that deal with radiopharmaceuticals right now.

Post 2

This is a really interesting article. I think the one barrier to using these medicines would be to pregnant or nursing women. I know the dose of radioactive material is small, but it could still affect the development of the baby negatively or pass on to the infant through the mom's milk.

My other concern is about where radiopharmaceuticals are made? Is it in labs or nuclear facilities?

Post 1

I know that the big disadvantage of chemotherapy as a cancer treatment is that it does a lot of harm to normal cells as well. I'm so happy to hear that there is now an alternative radiation treatment that doesn't do that.

I'm assuming though, that radiopharmaceuticals are more expensive than chemotherapy and radiotherapy, correct?

Do you think that will be a problem with insurance companies covering radiopharmaceuticals?

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