Pharmacological properties : תכונות פרמקולוגיות

Pharmacodynamic Properties

5.1   Pharmacodynamic properties
Pharmacotherapeutic group: diagnostic radiopharmaceuticals, central nervous system, ATC code: V09A A01

Pharmacotherapeutic group: diagnostic radiopharmaceuticals, inflammation and infection detection, ATC code: V09H A02

At the chemical concentrations and activities used for diagnostic procedures technetium - 99m exametazime and technetium-99m-labelled leucocytes do not appear to exert any pharmacodynamic effects.

Pharmacokinetic Properties

5.2   Pharmacokinetic properties

(1)            Direct intravenous injection
The technetium-99m complex of the active ingredient is uncharged, lipophilic and of sufficiently low molecular weight to cross the blood-brain barrier. It is rapidly cleared from the blood after intravenous injection. Uptake in the brain reaches a maximum of 3.5- 7.0% of the injected dose within one minute of injection. Up to 15% of the cerebral activity washes out of the brain 2 minutes post injection after which there is little loss of activity for the following 24 hours except by physical decay of technetium-99m. The activity not associated with the brain is widely distributed throughout the body particularly in muscle and soft tissue.

About 20% of the injected dose is removed by the liver immediately after injection and excreted through the hepatobiliary system. About 40% of the injected dose is excreted through the kidneys and urine over the 48 hours after injection resulting in a reduction in general muscle and soft tissue background.

(2)            Injection of labelled leucocytes

Technetium-99m-labelled leucocytes distribute between the marginating pools of the liver (within 5 minutes) and spleen (within about 40 minutes), and the circulating pool, (the latter represents approximately 50% of the leucocyte pool). Approximately 37% of the cell associated technetium-99m is recoverable from the circulating pool 40 minutes after injection. Technetium-99m activity is slowly eluted from the cells and is excreted partly by the kidneys and partly via the liver into the gall bladder. This results in increasing amounts of activity being seen in the intestines.