11.3 External Radiation The point source air-kerma coefficient for F 18 is 3.75 × 10 -17 Gy m 2 /(Bq s). 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 5. The use of 8 cm of Pb will decrease the radiation transmission (i.e., exposure) by a factor of about 10,000. Table 5: Radiation Attenuation of 511 keV Gamma Rays by Lead Shielding 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
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of action
Flotufolastat F 18 binds to PSMA (IC50 = 4.4 nM) expressed on cells, including prostate cancer cells, and is internalized. Prostate cancer cells usually overexpress PSMA. Fluorine- 18 is a ß+ emitting radionuclide that can be detected using positron emission tomography. 12.2 Pharmacodynamics The relationship between flotufolastat F 18 plasma concentrations and image interpretation has not been fully characterized. 12.3 Pharmacokinetics Distribution Following intravenous administration, flotufolastat F 18 distributes to liver (15.8% of administered activ ity), heart blood pool (7.4%), and kidneys (3.2%) and is cleared from the blood.
Elimination Metabolism Flotufolastat F 18 does not undergo metabolism up to 50 minutes post injection. Excretion
Elimination is by urinary excretion. Appr oximately 7% of the administered activity was excreted in the urine in the first 2 hours post- injection with approximately 15% excreted by 4.5 hours post -injection.
Page 8 of 12
Reference ID: 5180081
Made with FlippingBook flipbook maker