NeoTect® (Kit for the Preparation of Technetium Tc 99m Depreotide Injection)
is intended for use in the preparation of Technetium Tc 99m Depreotide, a diagnostic
radiopharmaceutical to be used by intravenous injection. Each vial contains
a sterile, non-pyrogenic lyophilized mixture of 47 µg of Depreotide,
75 mg of sodium glucoheptonate dihydrate, 50 µg of stannous chloride
dihydrate (with a minimum stannous tin content of 20 µg), 100 µg
edetate disodium dihydrate, 10 mg of sodium iodide, and sufficient sodium hydroxide
or hydrochloric acid for adjustment to pH 7.4 prior to lyophilization. The lyophilized
powder is sealed under a nitrogen atmosphere with a rubber closure. The product
contains no antimicrobial preservative.
Cyclo (L- homocysteinyl-N- methyl- L-phenylalanyl- L-tyrosyl- D-tryptophyl-
L-lysyl-L- valyl), (1→1')-sulfide with 3-[(mercaptoacetyl)amino]-L-alanyl-L-
lysyl- L-cysteinyl- L- lysinamide
The structural formula of Depreotide is:
When sterile, non-pyrogenic Sodium Pertechnetate Tc 99m Injection, in 0.9% Sodium Chloride Injection, U.S.P., is added to the vial, a Technetium Tc 99m complex of Depreotide is formed.
Technetium Tc 99m decays by isomeric transition with a physical half- life of 6.02 hours. The photon that is useful for imaging studies is listed in Table 1.
Table 1. Principal radiation emission data for Technetium
||Mean Percent per Disintegration
||Mean Energy (keV)
The specific gamma-ray constant for Technetium Tc 99m is 5.4 microcoulombs/kg·MBq·hour (0.78 R/mCi·hour) at 1 cm. The first half- value thickness of lead for Technetium Tc 99m is 0.17 mm. A range of values for the relative attenuation of the radiation emitted by this radionuclide that results from the interposition of various thicknesses of lead is shown in Table 2. For example, the use of a 0.25 cm thickness of lead will decrease the external radiation exposure by a factor of 1,000.
Table 2. Radiation attenuation by lead shielding.
|Lead Shield Thickness (cm)
||Coefficient of Attenuation
To correct for physical decay of this radionuclide, the fractio ns that remain at selected intervals relative to the time of calibration are shown in Table 3.
Table 3. Physical decay chart: Technetium Tc 99m half- life
Last reviewed on RxList: 12/1/2008
This monograph has been modified to include the generic and brand name in many instances.