Amyvid (Florbetapir F 18)


Indications

Amyvid is indicated for Positron Emission Tomography (PET) imaging of the brain to estimate β-amyloid neuritic plaque density in adult patients with cognitive impairment who are being evaluated for Alzheimer’s Disease (AD) and other causes of cognitive decline. A negative Amyvid scan indicates sparse to no neuritic plaques and is inconsistent with a neuropathological diagnosis of AD at the time of image acquisition; a negative scan result reduces the likelihood that a patient’s cognitive impairment is due to AD. A positive Amyvid scan indicates moderate to frequent amyloid neuritic plaques; neuropathological examination has shown this amount of amyloid neuritic plaque is present in patients with AD, but may also be present in patients with other types of neurologic conditions as well as older people with normal cognition. Amyvid is an adjunct to other diagnostic evaluations.

Limitations of Use:

  • A positive Amyvid scan does not establish a diagnosis of AD or other cognitive disorder.
  • Safety and effectiveness of Amyvid have not been established for:
    • Predicting development of dementia or other neurologic condition;
    • Monitoring responses to therapies.

contraindications


None

adverse reactions

6.1 Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug 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 studies, 555 patients were exposed to Amyvid. Amyvid caused no serious adverse reactions in the studies and the reported adverse reactions were predominantly mild to moderate in severity. The adverse reactions reported in more than one subject within the studies are shown in Table 2.

Table 2: Adverse Reactions Reported in Clinical Trials (N=555 patients)

a Includes the terms blood pressure increased and hypertension.

b Includes the terms injection site haemorrhage, injection site irritation, and injection site pain.

c Includes the terms feeling cold and chills.

Adverse Reactions N (Percent of patients)
Headache 10 (1.8%)
Musculoskeletal pain 4 (0.7%)
Blood pressure increaseda 4 (0.7%)
Nausea 4 (0.7%)
Fatigue 3 (0.5%)
Injection site reactionb 3 (0.5%)
Anxiety 2 (0.4%)
Back pain 2 (0.4%)
Claustrophobia 2 (0.4%)
Dizziness 2 (0.4%)
Feeling coldc 2 (0.4%)
Insomnia 2 (0.4%)
Neck pain 2 (0.4%)

Other adverse reactions occurred at lower frequencies and included infusion site rash, dysgeusia, pruritis, urticaria, and flushing.

warnings and precautions

5.1 Risk for Image Misinterpretation and other Errors

Errors may occur in the Amyvid estimation of brain neuritic plaque density during image interpretation.

Image interpretation should be performed independently of the patient’s clinical information. The use of clinical information in the interpretation of Amyvid images has not been evaluated and may lead to errors. Other errors may be due to extensive brain atrophy that limits the ability to distinguish gray and white matter on the Amyvid scan as well as motion artifacts that distort the image.

Amyvid scan results are indicative of the brain neuritic amyloid plaque content only at the time of image acquisition and a negative scan result does not preclude the development of brain amyloid in the future.

5.2 Radiation Risk

Amyvid, similar to other radiopharmaceuticals, contributes to a patient’s overall long-term cumulative radiation exposure. Long-term cumulative radiation exposure is associated with an increased risk of cancer. Ensure safe handling to protect patients and health care workers from unintentional radiation exposure.

description

Amyvid contains florbetapir F 18, a molecular imaging agent that binds to β-amyloid aggregates, and is intended for use with PET imaging of the brain. Chemically, florbetapir F 18 is described as (E)-4-(2-(6-(2-(2-(2[18F] fluoroethoxy)ethoxy)ethoxy)pyridine-3-yl)vinyl)-N-methylbenzamine. The molecular weight is 359 and the structural formula is:

Amyvid is a sterile, non-pyrogenic radioactive diagnostic agent for intravenous injection. The clear, colorless solution is supplied ready to use and each milliliter contains 0.1 to 19 micrograms of florbetapir and 500 – 1900 MBq (13.5 – 51 mCi) florbetapir F 18 at EOS, 4.5 mg sodium ascorbate USP and 0.1 mL dehydrated alcohol USP in 0.9% sodium chloride injection USP. The pH of the solution is between 5.5 and 7.5.

11.1 Physical Characteristics

Amyvid is radiolabeled with [18F] fluorine (F 18) that decays by positron (β+) emission to O 18 and has a half-life of 109.77 minutes. The principal photons useful for diagnostic imaging are the coincident pair of 511 keV gamma photons, resulting from the interaction of the emitted positron with an electron (Table 3).

Table 3: Principal Radiation Produced from Decay of Fluorine 18
Radiation Energy Level (keV) Abundance (%)
Positron 249.8 96.9
Gamma 511 193.5

11.2 External Radiation

The point source air-kerma coefficienta 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 mmb. 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

a Eckerman KF and A Endo. MIRD: Radionuclide Data and Decay Schemes, 2nd Edition, 2008.

b Derived from data in NCRP Report No. 49. 1998, Appendix C

Shield Thickness
cm of lead (Pb)
Coefficient of Attenuation
0.6 0.5
2 0.1
4 0.01
6 0.001
8 0.0001

Amyvid Package Photos

About the Author

Truman Lewis
Truman has been a bureau chief and correspondent in D.C., Los Angeles, Phoenix and elsewhere, reporting for radio, television, print and news services, for more than 30 years. Most recently, he has reported extensively on health and consumer issues for ConsumerAffairs.com and FairfaxNews.com.