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(flutemetamol F 18) for Injection
Vizamyl contains flutemetamol F 18, a molecular imaging agent that binds to β-amyloid aggregates, and is intended for use with PET imaging of the brain. Chemically, flutemetamol F 18, is described as 2-[3-[18F]fluoro-4-(methylamino) phenyl]-6-benzothiazolol. It has the molecular formula C14H1118FN2OS, molecular weight 273.32, and the following structural formula:
Vizamyl is a sterile, non-pyrogenic, clear, colorless to slightly yellow radioactive solution for intravenous injection. Each milliliter (mL) of the no-carrier added Vizamyl product solution contains 150 MBq (4.05 mCi) of flutemetamol F 18 at reference date and time and up to 2 micrograms of flutemetamol. Each mL of the Vizamyl solution also contains 70 microliters ethanol, 9.0 mg sodium chloride and 4.98 mg polysorbate 80 (w/v) in 0.014 M aqueous phosphate buffer. The pH of the solution is between 6.0 and 8.5.
Fluorine-18 (F 18) is a cyclotron-produced radionuclide that decays by positron emission (ß+ decay, 96.7%) and orbital electron capture (3.3%) to stable oxygen-18 with a physical half-life of 109.8 minutes. The positron can undergo annihilation with an electron to produce two gamma rays; the energy of each gamma ray is 511 keV (Table 3).
Table 3: Principal Radiation
Emission Data – Fluorine-18
The point source air-kerma rate constant for F-18 is 3.74E -17 Gy m²/(Bq s); this coefficient was formerly defined as the specific gamma-ray constant of 5.7 R/hr/mCi at 1 cm. The first half-value thickness of lead (Pb) for F 18 gamma rays is approximately 6 mm. The relative reduction of radiation emitted by F-18 that results from various thicknesses of lead shielding is shown in Table 4. The use of ~8 cm of Pb will decrease the radiation transmission (i.e., exposure) by a factor of about 10,000.
Table 4: Radiation
Attenuation of 511 keV Gamma Rays by Lead Shielding
|Shielding Thickness cm of lead (Pb)||Coefficient of Attenuation|
Last reviewed on RxList: 12/18/2014
This monograph has been modified to include the generic and brand name in many instances.
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