Radiopharmacology

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Radiopharmacology is the study and preparation of radiopharmaceuticals, which are radioactive pharmaceuticals. Radiopharmaceuticals are used in the field of nuclear medicine as tracers in the diagnosis and treatment of many diseases. Many radiopharmaceuticals use technetium-99m (Tc-99m) which has many useful properties as a gamma-emitting tracer nuclide. In the book Technetium a total of 31 different radiopharmaceuticals based on Tc-99m are listed for imaging and functional studies of the brain, myocardium, thyroid, lungs, liver, gallbladder, kidneys, skeleton, blood and tumors.[1]

The term radioisotope, which in its general sense refers to any radioactive isotope (radionuclide), has historically been used to refer to all radiopharmaceuticals, and this usage remains common. Technically, however, many radiopharmaceuticals incorporate a radioactive tracer atom into a larger pharmaceutically-active molecule, which is localized in the body, after which the radionuclide tracer atom allows it to be easily detected with a gamma camera or similar gamma imaging device. An example is fludeoxyglucose in which fluorine-18 is incorporated into deoxyglucose. Some radioisotopes (for example gallium-67, gallium-68, and radioiodine) are used directly as soluble ionic salts, without further modification. This use relies on the chemical and biological properties of the radioisotope itself, to localize it within the body.

Lead container for iodine-123 capsule

History[edit]

See nuclear medicine.

Production[edit]

Production of a radiopharmaceutical involves two processes:

  • The production of the radionuclide on which the pharmaceutical is based.
  • The preparation and packaging of the complete radiopharmaceutical.

Radionuclides used in radiopharmaceuticals are mostly radioactive isotopes of elements with atomic numbers less than that of bismuth, that is, they are radioactive isotopes of elements that also have one or more stable isotopes. These may be roughly divided into two classes:

  • Those with excess neutrons in the nucleus to those required for stability are known as proton-deficient, and tend to be most easily produced in a nuclear reactor, the majority of radiopharmaceuticals are based on proton deficient isotopes, with technetium-99m being the most commonly used medical isotope, and therefore nuclear reactors are the prime source of medical radioisotopes.[2]
  • Those with fewer neutrons in the nucleus to those required for stability are known as neutron-deficient, and tend to be most easily produced using a proton accelerator such as a medical cyclotron.

Practical use[edit]

Because radiopharmeuticals require special licenses and handling techniques, they are often kept in local centers for medical radioisotope storage, often known as radiopharmacies. A radiopharmacist may dispense them from there, to local centers where they are handled at the practical medicine facility.

Drug nomenclature for radiopharmaceuticals[edit]

As with other pharmaceutical drugs, there is standardization of the drug nomenclature for radiopharmaceuticals, although various standards coexist. The International Nonproprietary Name (INN) gives the base drug name, followed by the radioisotope (as atomic weight, no space, element symbol) in parentheses with no superscript, followed by the ligand (if any). It is common to see square brackets and superscript superimposed onto the INN name, because chemical nomenclature (such as IUPAC nomenclature) uses those. The United States Pharmacopeia (USP) name gives the base drug name, followed by the radioisotope (as element symbol, space, atomic weight) with no parentheses, no hyphen, and no superscript, followed by the ligand (if any). The USP style is not the INN style, despite their being described as one and the same in some publications (e.g., AMA,[3] whose style for radiopharmaceuticals matches the USP style). The United States Pharmacopeial Convention is a sponsor organization of the USAN Council, and the USAN for a given drug is often the same as the USP name.

International Nonproprietary Name (INN) United States Pharmacopeia (USP) Comments
technetium (99mTc) sestamibi technetium Tc 99m sestamibi  
fludeoxyglucose (18F) fludeoxyglucose F 18  
sodium iodide (125I) sodium iodide I 125  
indium (111In) altumomab pentetate indium In 111 altumomab pentetate  

Specific radiopharmaceuticals[edit]

A list of nuclear medicine radiopharmaceuticals follows. Some radioisotopes* are used in ionic or inert form without attachment to a pharmaceutical, these are also included. There is a section for each radioisotope with a table of radiopharmaceuticals using that radioisotope. The sections are ordered alphabetically by the English name of the radioisotope. Sections for the same element are then ordered by atomic mass number.

Calcium-47[edit]

47Ca is a beta and gamma emitter.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
Ca-47-Ca2+ Bone metabolism IV In-vitro Non-imaging

Carbon-11[edit]

11C is a positron emitter.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
C11-L-methyl-methionine Brain tumour imaging

Parathyroid imaging

IV In-vivo Imaging

Carbon-14[edit]

14C is a beta emitter.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
C14-Glycocholic acid Breath test for small intestine bacterial overgrowth Oral In-vitro Non-imaging
C14-PABA (para-amino benzoic acid) Pancreatic studies Oral In-vitro Non-imaging
C14-Urea Breath test to detect Helicobacter pylori Oral In-vitro Non-imaging
C14-d-xylose Breath test for small intestine bacterial overgrowth Oral In-vitro Non-imaging

Chromium-51[edit]

51Cr is a gamma emitter.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
Cr51-Red blood cells Red cell volume; sites of sequestration; gastrointestinal blood loss IV In-vitro Non-imaging
Cr51-Cr3+ Gastrointestinal protein loss IV In-vitro Non-imaging
Cr51-EDTA (ethylenediaminetetraacetic acid) Glomerular filtration rate measurement IV In-vitro Non-imaging

Cobalt-57[edit]

57Co is a gamma emitter.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
Co57-Cyanocobalamin (vitamin B12) Gastrointestinal absorption Oral In-vitro Non-imaging

Cobalt-58[edit]

58Co is a gamma emitter.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
Co58-Cyanocobalamin (vitamin B12) Gastrointestinal absorption Oral In-vitro Non-imaging

Erbium-169[edit]

169Er is a beta emitter.

Name Treatment of Route of administration
Er169-Colloid Arthritic conditions Intra-articular

Fluorine-18[edit]

18F is a positron emitter with a half life of 109 minutes. It is produced in medical cyclotrons, usually from oxygen-18, and then chemically attached to a pharmaceutical. See PET scan.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
F18-FDG (Fluorodeoxyglucose) Tumor imaging

Myocardial imaging

IV In-vivo Imaging
F18-Sodium Fluoride Bone imaging IV In-vivo Imaging
F18-Fluorocholine Prostate tumor imaging IV In-vivo Imaging
F18-Desmethoxyfallypride Dopamine receptor imaging IV In-vivo Imaging

Gallium-67[edit]

67Ga is a gamma emitter. See gallium scan.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
Ga67-Ga3+ Tumor imaging IV In-vivo Imaging
Ga67-Ga3+ Infection/inflammation imaging IV In-vivo Imaging

Gallium-68[edit]

68Ga is a positron emitter, with a 68 minute half life, produced by elution from germanium-68 in a gallium-68 generator. See also positron emission tomography.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
Ga68-Dotatoc or Dotatate Neuroendocrine tumor imaging IV In-vivo Imaging

Hydrogen-3[edit]

3H or tritium is a beta emitter.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
H3-water Total body water Oral or IV In-vitro Non-imaging

Indium-111[edit]

111In is a gamma emitter.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
In111-DTPA (diethylenetriaminepenta-acetic acid) Ventriculo-peritoneal shunt (LaVeen Shunt) intraperitoneal injection In-vivo Imaging the radioactive substance
In111-DTPA (diethylenetriaminepenta-acetic acid) Cisternography Intra-cisternal In-vivo Imaging
In111-Leukocytes Infection/inflammation imaging IV In-vivo Imaging
In111-Platelets Thrombus imaging IV In-vivo Imaging
In111-Pentetreotide Somatostatin receptor imaging IV In-vivo Imaging
In111-Octreotide Somatostatin receptor imaging (Octreoscan) IV In-vivo Imaging

Iodine-123[edit]

123I is a gamma emitter. It is used only diagnostically, as its radiation is penetrating and short-lived.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
I123-Iodide Thyroid uptake Oral or IV In-vivo Non-imaging
I123-Iodide Thyroid imaging

Thyroid metastases imaging

Oral or IV In-vivo Imaging
I123-o-Iodohippurate Renal imaging IV In-vivo Imaging
I123-MIBG (m-iodobenzylguanidine) Neuroectodermal tumour imaging IV In-vivo Imaging
I123-FP-CIT SPECT imaging of Parkinson's Disease IV In-vivo Imaging

Iodine-125[edit]

125I is a gamma emitter with a long half-life of 59.4 days (the longest of all radioiodines used in medicine). Iodine-123 is preferred for imaging, so I-125 is used diagnostically only when the test requires a longer period to prepare the radiopharmaceutical and trace it, such as a fibrinogen scan to diagnose clotting. I-125's gamma radiation is of medium penetration, making it more useful as a therapeutic isotope for brachytherapy implant of radioisotope capsules for local treatment of cancers.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
I125-fibrinogen Clot imaging IV In-vivo Imaging

Iodine-131[edit]

131I is a beta and gamma emitter. It is used both to destroy thyroid and thyroid cancer tissues (via beta radiation, which is short-range), and also other neuroendocrine tissues when used in MIBG. It can also be seen by a gamma camera, and can serve as a diagnostic imaging tracer, when treatment is also being attempted at the same time. However iodine-123 is usually preferred when only imaging is desired.

Diagnostic[edit]

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
I131-Iodide Thyroid uptake Oral In-vivo Non-imaging
I131-Iodide Thyroid metastases imaging Oral or IV In-vivo Imaging
I131-MIBG (m-iodobenzylguanidine) Neuroectodermal tumor imaging IV In-vivo Imaging

Therapeutic[edit]

Name Treatment of Route of administration
I131-Iodide Thyrotoxicosis IV or Oral
I131-Iodide Non-toxic goiter IV or Oral
I131-Iodide Thyroid carcinoma IV or Oral
I131-MIBG (m-iodobenzylguanidine) Malignant disease IV

Iron-59[edit]

59Fe is a beta and gamma emitter.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
Fe59-Fe2+ or Fe3+ Iron metabolism IV In-vitro Non-imaging

Krypton-81m[edit]

81Krm is a gamma emitter.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging the radio active substance
Kr81m-Gas Lung ventilation imaging Inhalation In-vivo Imaging
Kr-81m-Aqueous solution Lung perfusion imaging IV In-vivo Imaging

Nitrogen-13[edit]

13N is a positron emitter.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
N13-Ammonia Myocardial blood flow imaging IV In-vivo Imaging

Oxygen-15[edit]

15O is a positron emitter.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
O15-Water Cerebral blood flow imaging

Myocardial blood flow imaging

IV bolus In-vivo Imaging

Phosphorus-32[edit]

32P is a beta emitter.

Name Treatment of Route of administration
P32-Phosphate Polycythemia and related disorders IV or Oral

Radium-223[edit]

223Ra is an alpha emitter.

Name Treatment of Route of administration
Ra223 cation (223RaCl2) metastatic cancer in bone IV

Rubidium-82[edit]

82Rb is a positron and gamma emitter.

Name Treatment of Route of administration
Rb-82 Chloride Myocardial Imaging IV

Samarium-153[edit]

153Sm is a beta and gamma emitter.

Name Treatment of Route of administration
Sm153-EDTMP (Ethylenediaminotetramethylenephosphoric acid) Bone metastases IV

Selenium-75[edit]

75Se is a gamma emitter.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
Se75-Selenorcholesterol Adrenal gland imaging IV In-vivo Imaging
Se75-SeHCAT (23-Seleno-25-homo-tauro-cholate) Bile salt absorption Oral In-vivo Imaging

Sodium-22[edit]

22Na is a positron and gamma emitter.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
Na22-Na+ Electrolyte studies Oral or IV In-vitro Non-imaging

Sodium-24[edit]

24Na is a beta and gamma emitter.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
Na24-Na+ Electrolyte studies Oral or IV In-vitro Non-imaging

Strontium-89[edit]

89Sr is a beta emitter.

Name Treatment of Route of administration
Sr89-Chloride Bone metastases IV

Technetium-99m[edit]

99Tc is a gamma emitter. It is obtained on-site at the imaging center as the soluble pertechnetate which is eluted from a technetium-99m generator, and then either used directly as this soluble salt, or else used to synthesize a number of technetium-99m-based radiopharmaceuticals.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
Tc99m-pertechnetate Thyroid uptake and thyroid imaging

Stomach and salivary gland imaging
Meckel's diverticulum imaging
Brain imaging
Micturating cystogram
First pass blood flow imaging
First pass peripheral vascular imaging

IV In-vivo Imaging
Tc99m-pertechnetate Lacrimal imaging Eye drops In-vivo Imaging
Tc99m-Human albumin Cardiac blood pool imaging IV In-vivo Imaging
Tc99m-Human albumin Peripheral vascular imaging IV In-vivo Imaging
Tc99m-Human albumin macroaggregates or microspheres Lung perfusion imaging IV In-vivo Imaging
Tc99m-Human albumin macroaggregates or microspheres Lung perfusion imaging with venography IV In-vivo Imaging
Tc99m-Phosphonates and phosphates (MDP/HDP) Bone imaging IV In-vivo Imaging
Tc99m-Phosphonates and phosphates Myocardial imaging IV In-vivo Imaging
Tc99m-DTPA (diethylenetriaminepenta-acetic acid) Renal imaging
First pass blood flow studies
Brain imaging
IV In-vivo Imaging
Tc99m-DTPA (diethylenetriaminepenta-acetic acid) Lung ventilation imaging Aerosol inhalation In-vivo Imaging
Tc99m-DMSA(V) (dimercaptosuccinic acid) Tumor imaging IV In-vivo Imaging
Tc99m-DMSA(III) (dimercaptosuccinic acid) Renal imaging IV In-vivo Imaging
Tc99m-Colloid Bone marrow imaging

GI Bleeding

IV In-vivo Imaging
Tc99m-Colloid Lymph node imaging Interstitial In-vivo Imaging
Tc99m-Colloid Esophageal transit and reflux imaging

Gastric emptying imaging

Oral In-vivo Imaging
Tc99m-Colloid Lacrimal imaging Eye drops In-vivo Imaging
Tc99m-HIDA (Hepatic iminodiacetic acid) Functional biliary system imaging IV In-vivo Imaging
Tc99m-Denatured (heat damaged) red blood cells Red cell volume

Spleen imaging

IV In-vitro Non-imaging
Tc99m-Whole red blood cells GI bleeding

Cardiac blood pool imaging
Peripheral vascular imaging

IV In-vivo Imaging
Tc99m-MAG3 (mercaptoacetyltriglycine) Renal imaging

First pass blood flow imaging

IV In-vivo Imaging
Tc99m-Exametazime (HMPAO) Cerebral blood flow imaging IV In-vivo Imaging
Tc99m-Exametazime labelled leucocytes Infection/inflammation imaging IV In-vivo Imaging
Tc99m-Sestamibi (MIBI - methoxy isobutyl isonitrile) Parathyroid imaging

Non-specific tumor imaging
Thyroid tumor imaging
Breast imaging
Myocardial imaging

IV In-vivo Imaging
Tc99m-Sulesomab (IMMU-MN3 murine Fab'-SH antigranulocyte monoclonal antibody fragments) Infection/inflammation imaging IV In-vivo Imaging
Tc99m-Technegas Lung ventilation imaging Inhalation In-vivo Imaging
Tc99m-Human immunoglobulin Infection/inflammation imaging IV In-vivo Imaging
Tc99m-Tetrofosmin Parathyroid imaging

Myocardial imaging

IV In-vivo Imaging
Tc99m-ECD (ethyl cysteinate dimer) Brain imaging----- IV In-vivo Imaging

...

Thallium-201[edit]

201Tl is a gamma emitter.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
Tl201-Tl+ Non-specific tumor imaging

Thyroid tumor imaging
Myocardial imaging
Parathyroid imaging

IV In-vivo Imaging

Xenon-133[edit]

133Xe is a gamma emitter.

Name Investigation Route of administration In-vitro / in-vivo Imaging / non-imaging
Xe133-gas Lung ventilation studies Inhalation In-vivo Imaging
Xe133 in isotonic sodium chloride solution Cerebral blood flow IV In-vivo Imaging

Yttrium-90[edit]

90Y is a beta emitter.

Name Treatment of Route of administration
Y90-Silicate Arthritic conditions Intra-articular
Y90-Silicate Malignant disease Intracavitary

See also[edit]

References[edit]

  1. ^ Schwochau, Klaus. Technetium. Wiley-VCH (2000). ISBN 3-527-29496-1
  2. ^ http://www.sciencedaily.com/releases/2010/07/100708111326.htm
  3. ^ Iverson, Cheryl, et al. (eds) (2007), "15.9.2 Radiopharmaceuticals", AMA Manual of Style (10th ed.), Oxford, Oxfordshire: Oxford University Press, ISBN 978-0-19-517633-9. 

Reading[edit]

  • Notes for guidance on the clinical administration of radiopharmaceuticals and use of sealed radioactive sources. Administration of radioactive substances advisory committee. March 2006. Produced by the Health Protection Agency.
  • Malabsorption. In: The Merck Manual of Geriatrics, chapter 111.
  • Leukoscan summary of product characteristics (Tc99m-Sulesomab).
  • Schwochau, Klaus. Technetium. Wiley-VCH (2000). ISBN 3-527-29496-1

External links[edit]