Flutemetamol F 18 Injection

Name: Flutemetamol F 18 Injection

Description

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.

Physical Characteristics

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

Radiation Energy (keV) Abundance (%)
Gamma 511 193.4
Positron 249.8 96.7

External Radiation

The point credit 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
0.6 0.5
2 0.1
4 0.01
6 0.001
8 0.0001

Side effects

Clinical Trials Experience

Clinical trials are conducted under widely varying conditions and adverse reaction rates observed in the clinical trials of Vizamyl cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice. In clinical trials, 761 adults (367 men and 394 women, 91% Caucasian) with a mean age of 62 years (range 18-93 years) received Vizamyl. Most subjects (530, 70%) received a dose of 185 MBq (5 mCi).

One subject out of 761 administered Vizamyl experienced a serious hypersensitivity reaction with flushing, dyspnea and chest pressure within minutes following Vizamyl administration and recovered with treatment.

Most adverse reactions were mild to moderate in intensity and resolved spontaneously. The most commonly reported adverse reactions (occurring in at least 1% of subjects) in Vizamyl-treated subjects are shown in Table 2.

Table 2: Adverse Reactions Reported in Clinical Trials of Vizamyl (N = 761 subjects)

Adverse Reaction N (percent of patients)
Flushing 16 (2%)
Increased blood pressure 13 (2%)
Headache 10 (1%)
Nausea 8 (1%)
Dizziness 8 (1%)

Read the entire FDA prescribing information for Vizamyl (Flutemetamol F 18 Injection)

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