The kit consists of reaction vials which contain the sterile, non-pyrogenic, non-radioactive ingredients necessary to produce Technetium Tc 99m Medronate Injection for diagnostic use by intravenous injection. MDP-25 (kit for the preparation of technetium tc 99m medronate injection) reaction vials are intended to be used as multidose vials.

Each 10 mL MDP-25 (kit for the preparation of technetium tc 99m medronate injection) reaction vial contains 25.0 mg medronic acid and not less than 2.0 mg of stannous chloride dihydrate (maximum total tin expressed as stannous chloride dihydrate 3.0 mg) and 5.0 mg of p-aminobenzoic acid in lyophilized form under an atmosphere of nitrogen.

The pH is adjusted to 6.8 to 6.9 with HCI or NaOH prior to lyophilization. The addition of sterile, non-pyrogenic, and oxidant-free sodium pertechnetate Tc 99m sterile solution produces a rapid labeling which is essentially quantitative and which remains stable in vitro throughout the 12-hours life of the preparation. No bacteriostatic preservative is present.

The structural formula of medronic acid is:

Medronic acid Structural Formula Illustration

Physical Characteristics

Technetium Tc 99m decays by isomeric transition with a physical half-life of 6.02 hours.1 The principal photon that is useful for detection and imaging studies is listed in Table 1.


Radiation Mean %/ Disintegration Energy (keV)
Gamma-2 89.07 140.5

External Radiation

The specific gamma ray constant for Tc 99m is 0.78 R/mCi-hr at 1 cm. The first half value layer is 0.017 cm of lead. To facilitate control of the radiation exposure from millicurie amounts of this radionuclide, the use of a 0.25 cm thickness of lead will attenuate the radiation emitted by a factor of about 1,000. A range of values for the relative attenuation of the radiation emitted by this radionuclide that results from interposition of various thicknesses of lead is shown in Table 2.


Shield Thickness (Pb) cm Coefficient of Attenuation
0.017 0.5
0.08 10-1
0.16 10-2
0.25 10-3
0.33 10-4

To correct for physical decay of this radionuclide, the fractions that remain at selected intervals after the time of calibration are shown in Table 3.

Table 3 : PHYSICAL DECAY CHART: TC 99m, half-life 6.02 hours

Hours Fraction
Hours Fraction
0* 1.000 7 0.447
1 0.891 8 0.398
2 0.794 9 0.355
3 0.708 10 0.316
4 0.631 11 0.282
5 0.562 12 0.251
6 0.501    
* Calibration time

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