KIT FOR THE PREPARATION OF TECHNETIUM TC 99M MEDRONATE FOR INJECTION- medronic acid injection, powder, lyophilized, for solution
Kit for the Preparation of Technetium Tc 99m Medronate is a multidose reaction vial which contains the sterile, non-pyrogenic, non-radioactive ingredients necessary to produce Technetium Tc 99m Medronate Injection for diagnostic use by Intravenous injection.
Each 10mL multidose vial contains:
- Medronic acid: 20 mg
- Ascorbic acid: 1 mg
- Stannous fluoride, SnF2 : 0.13 mg (minimum)
- Total tin (maximum, as stannous fluoride, SnF2 ): 0.38 mg
The pH is adjusted to 6.5 (6.3 to 6.7) with sodium hydroxide and/or hydrochloric acid prior to lyophilization. No bacteriostatic preservative is present in the vial. The contents of the vial are lyophilized and sealed under nitrogen at the time of manufacture. The structural formula is:
When a solution of sterile, non-pyrogenic, oxidant-free Sodium Pertechnetate Tc 99m Injection is added to the vial, the diagnostic agent, Technetium Tc 99m Medronate is formed for administration by intravenous injection. The pH of the reconstituted product is 5.4 to 6.8. The precise structure of Technetium Tc 99m Medronate Injection is not known at this time.
Technetium Tc 99m decays by isomeric transition with a physical half-life of 6.02 hours1. The principal photon that is useful for detection and imaging studies is listed in Table 1.
|Radiation||Mean % per Disintegration||Mean Energy (keV)|
1 Kocher, DC: Radioactive Decay Data Tables, DOE/TIC-11026, 108, 1981.
The specific gamma ray constant for Tc 99m is 0.78 R/millicurie-hr at 1 cm. The first half-value layer is 0.017 cm of lead (Pb). A range of values for the relative attenuation of the radiation emitted by this radionuclide that results from interposition of the various thicknesses of Pb is shown in Table 2. To facilitate control of the radiation exposure from millicurie amounts of this radionuclide, the use of a 0.25 cm thickness of Pb will attenuate the radiation emitted by a factor of about 1,000.
|Shield Thickness (Pb) cm||Coefficient of Attenuation|
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.
|Hours||Fraction Remaining||Hours||Fraction Remaining|
* Calibration Time
During the initial 24 hours following intravenous injection of Technetium Tc 99m Medronate, about 50% of each dose is retained in the skeleton, and about 50% is excreted in the urine. Upon intravenous injection, Technetium Tc 99m Medronate exhibits a specific affinity for areas of altered osteogenesis. In humans, blood levels fall to 4 to 10% of the injected dose by two hours post-injection and to 3 to 5% by three hours.
Uptake of Technetium Tc 99m Medronate Injection in bone appears to be related to osteogenic activity and to skeletal blood perfusion. The deposition in the skeleton is bilaterally symmetrical, with increased accumulation in the axial structure as compared to the appendicular skeleton. There is increased activity in the distal aspect on long bones as compared to the diaphyses.
Technetium Tc 99m Medronate Injection may be used as a bone imaging agent to delineate areas of altered osteogenesis.
This class of compounds is known to complex cations such as calcium. Particular caution should be used with patients who have, or may be predisposed to hypocalcemia (i.e., alkalosis).
Preliminary reports indicate impairment of brain scans using Sodium Pertechnetate Tc 99m Injection which have been preceded by a bone scan using an agent containing stannous ions. The impairment may result in false-positive or false-negative brain scans. It is recommended, where feasible, that brain scans precede bone imaging procedures. Alternatively, a brain imaging agent such as Technetium Tc 99m Pentetate Injection may be employed.
Contents of the vial are intended only for use in the preparation of Technetium Tc 99m Medronate Injection and are NOT to be administered directly to the patient.
Technetium Tc 99m Medronate Injection as well as other radioactive drugs must be handled with care, and appropriate safety measures should be used to minimize radiation exposure to the patient and clinical personnel consistent with proper patient management.
To minimize radiation dose to the bladder, the patients should be encouraged to drink fluids and to void immediately before the examination and as often thereafter as possible for the next 4 to 6 hours.
Technetium Tc 99m Medronate Injection should be formulated within six (6) hours prior to clinical use. Optimal imaging results are obtained 1 to 4 hours after administration.
The finding of an abnormal concentration of radioactivity implies the existence of underlying pathology, but further study is required to distinguish benign from malignant lesions.
The image quality may be adversely affected by obesity, old age, or impaired renal function.
The components of the kit are sterile and non-pyrogenic. It is essential to follow directions carefully and to adhere to strict aseptic procedures during preparation. Technetium Tc 99m labeling reactions involved depend on maintaining the stannous ion in the reduced state. Hence, Sodium Pertechnetate Tc 99m Injection containing oxidants should not be used.
The preparation contains no bacteriostatic preservative. Technetium Tc 99m Medronate Injection should be stored at 20-25ºC (68-77ºF) and discarded 6 hours after reconstitution. The solution should not be used if the contents are cloudy.
Vials are sealed under nitrogen: air or oxygen is harmful to the contents of the vials and the vials should not be vented.
The components of the Kit for the Preparation of Technetium Tc 99m Medronate for Injection are supplied sterile and non-pyrogenic. Aseptic procedures normally employed in making additions and withdrawals for sterile, non-pyrogenic containers should be used during addition of the pertechnetate solution and the withdrawal of doses for patient administration. Shielding should be utilized when preparing Technetium Tc 99m Medronate Injection.
No special handling is required for the non-radioactive drug product.
Radiopharmaceuticals should be used only by physicians who are qualified by training and experience in the safe use and handling of radionuclides, and whose experience and training have been approved by the appropriate government agency authorized to license the use of radionuclides.
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