Nuclear Pharmacy and Radiopharmaceuticals

Radiopharmaceuticals

• A radioactive agent used for diagnostic or therapeutic procedures
• Overlapping jurisdictions: FDA and Nuclear Regulatory Commission (NRC)

Nuclear Pharmacy

• First specialty in pharmacy recognized by the Board of Pharmaceutical Specialities (1978)
• Focuses on the safe and effective use of radioactive drugs or radiopharmaceuticals

Radioisotopes/Radionuclides

• Artificially produced unstable atoms of a naturally occurring element
• Same number of electrons and protons as the naturally occurring element, but different number of neutrons
• Over 1000 radioisotopes known, but only 50 are naturally occurring

Production

• Produced by bombarding atoms of stable, naturally occurring elements with fast-moving neutrons
• Produced in a nuclear reactor or particle accelerator

Half-Life (t1/2)

• Rate of conversion of an isotope to its stable elemental composition

Types of Radiation

• Alpha radiation: result of excess energy dissipation by unstable nuclei in the form of alpha particles
• Alpha particles: 2 positive charges, 2 neutrons, and a total mass of 4 units, identical to a helium nucleus
• Alpha particles: travel about 1-4 inches in the air, ejected at about 1/10th the speed of light

Beta Radiation

• Produced through beta decay of unstable nuclei
• Follows electron emission, positron emission, or electron capture
• Beta particles: either electrons with negative charge (negatrons) or positive electrons (positrons)
• Beta particles: travel up to about 1 mm in tissue, have a range of more than 100 feet in air, and possess a lot of kinetic energy

Gamma Rays

• Most penetrating electromagnetic radiation of shortest wavelength and highest energy
• Produced by the decay of radioactive nuclei or certain subatomic particles
• Gamma rays: just below the x-ray region of the electromagnetic spectrum

Units of Radiation

• Curie (Ci): measures radioactivity/unit mass of material
• Becquerel (Bq): one Bq represents the amount of radiation produced from one disintegration/second
• One Ci is equal to 37 billion Bq or 37 GBq
• Rad: expresses the absorbed dose of ionizing radiation
• One Rad represents the amount of radiation that releases energy of 100 ergs/gm of matter
• Rem: expresses the dosage in Rads that causes the same amount of biological injury as 1 Rad of X-rays or gamma rays
• Roentgen (R): quantitates the exposure to radiation
• Erg: represents the amount of radiation that releases energy or work that equals 10-7 Joules
• SI system of units: Bq is the unit of radioactivity, Gray (Gy) is the unit of expression of absorbed dose, Sievert (Sv) is the dose equivalent unit, and exposure is represented in coulomb/kg body weight