Singapore Drugs Database

Indication

The uptake of 18F-FDG by tissues is a marker for the tissue uptake of glucose, which in turn is closely correlated with certain types of tissue metabolism. Fludeoxyglucose F 18 Injection is indicated in positron emission tomography (PET) imaging for assessment of abnormal glucose metabolism to assist in the evaluation of malignancy in patients with known or suspected abnormalities found by other testing modalities, or in patients with an existing diagnoses of cancer.

Mechanism of Action

Fludeoxyglucose F 18 is a glucose analog that concentrates in cells that rely upon glucose as an energy source, or in cells whose dependence on glucose increases under pathophysiological conditions. Fludeoxyglucose F 18 is transported through the cell membrane by facilitative glucose transporter proteins and is phosphorylated within the cell to [18F] FDG-6- phosphate by the enzyme hexokinase. Once phosphorylated it cannot exit until it is dephosphorylated by glucose-6-phosphatase. Therefore, within a given tissue or pathophysiological process, the retention and clearance of Fludeoxyglucose F 18 reflect a balance involving glucose transporter, hexokinase and glucose-6- phosphatase activities. When allowance is made for the kinetic differences between glucose and Fludeoxyglucose F 18 transport and phosphorylation (expressed as the “lumped constant” ratio), Fludeoxyglucose F 18 is used to assess glucose metabolism. In comparison to background activity of the specific organ or tissue type, regions of decreased or absent uptake of Fludeoxyglucose F 18 reflect the decrease or absence of glucose metabolism. Regions of increased uptake of Fludeoxyglucose F 18 reflect greater than normal rates of glucose metabolism.

Pharmacokinetics

Absorption

Fludeoxyglucose F 18 Injection is rapidly distributed to all organs of the body after intravenous administration.

Distribution

Fludeoxyglucose F 18 Injection is rapidly distributed to all organs of the body after intravenous administration.

Metabolism

Fludeoxyglucose F 18 is transported into cells and phosphorylated to [18F]-FDG-6-phosphate at a rate proportional to the rate of glucose utilization within that tissue. [18F]-FDG-6-phosphate presumably is metabolized to 2-deoxy-2-[18F] fluoro-6-phospho-Dmannose ([18F]FDM-6-phosphate). Fludeoxyglucose F 18 Injection may contain several impurities (e.g., 2-deoxy-2-chloro-D-glucose (ClDG)). Biodistribution and metabolism of C1DG are presumed to be similar to Fludeoxyglucose F 18 and would be expected to result in intracellular formation of 2-deoxy-2-chloro-6-phospho-D-glucose (C1DG-6-phosphate) and 2-deoxy-2-chloro-6-phospho-D-mannose (ClDM-6-phosphate). The phosphorylated deoxyglucose compounds are dephosphorylated and the resulting compounds (FDG, FDM, C1DG, and ClDM) presumably leave cells by passive diffusion.

Elimination

Clearance

Fludeoxyglucose F 18 and related compounds are cleared from non-cardiac tissues within 3 to 24 hours after administration. Clearance from the cardiac tissue may require more than 96 hours

Toxicity

Overdoses of Fludeoxyglucose F 18 Injection have not been reported.

Active Ingredient/Synonyms

(18F)-FDG | 18-F FDG | 18F-FDG | Fludeoxyglucose (18F) | Fludeoxyglucose F 18 | Fludeoxyglucose, F-18 | Fludeoxyglucose F-18 | Fluoro-2-Deoxy-D-Glucose |