153
Samarium ( Sm) Ethylene Diamine Tetramethylene Phosphonate
(EDTMP) Injection
Category. Therapeutic.
Description. A clear, colourless, sterile solution.
Samarium (153Sm) Ethylene Diamine Tetramethylene Phosphonate Injection contains not less than 90.0 per cent
and not more than 110.0 per cent of the stated Samarium-153 radioactivity at the date and time stated on the
label.
Identification
A. Determine by gamma-ray spectrometry. The most prominent gamma photon of samarium-153 has an
energy of 103KeV.
B. In the test for Radiochemical purity, the chromatogram obtained contributes to the identification of the
distribution of radioactivity in the injection.
Tests
pH (2.4.24). 7.0 to 8.0
Radioactivity assay. Measure the radioactivity using suitable counting equipment
Radionuclidic purity. Determine by gamma-ray spectrometry.
The total radioactivity due to radionuclidic impurities is not less than 99.8 per cent as samarium -153 and not
more than 0.01 per cent of the total radioactivity is due to europium-154. The sum of all gamma-emitting
impurities is not more than 0.2 per cent.
Calibrate the Gamma ray spectrometer using 152Eu / 137Cs as a standard source. Take a small aliquot of sample
in a vial / tube and place on the detector connected to a multi channel analyzer. Acquire the counts for sufficient
time interval. Identify the radionuclide 153Sm by the photopeak corresponding to its principal gamma emission
of 103 keV.
Radiochemical purity. Determine by paper chromatography (2.4.17), using cellulose paper strips.
Support: Whatman No.1 Chromatography Paper: 2 strips (3x 21cm), leave about 3 cms from the upper and
lower portion of the strip and make markings at 1cm distance up to 15cm .
Solvent: Normal saline
Spot about 2 µl of the sample at 3cm from bottom on the strip in duplicate. Develop the chromatogram by
ascending chromatography till the solvent front migrates to a distance of 10 cm from the point of spotting.
Remove the strips, allow to dry, cut the strips in to one cm. sections and count for radioactivity in a well type
NaI(Tl) scintillation counter . OR scan the chromatogram with collimator adjusted suitably to measure 153Sm.
Rf of 153Sm-EDTMP=1
Rf of impurity (free uncomplexed 153Sm) = 0
Calculate the % of radiochemical present in the form of 153Sm-EDTMP as follows:
% RCP = Activity in the 153Sm-EDTMP zone x 100 /Total Activity
% of radiochemical present in the form of 153Sm-EDTMP shall not be less than 95% of the total activity on the
day of determining the radiochemical purity.
Biodistribution. Not more than 5% of the injected radioactivity is present in the kidneys, not more than 5% in
the liver and not less than 2% is present in both femurs, in the wistar rats at 1 hour p.i.
Bacterial endotoxins (2.2.3). Not more than 175/VIU/ml, V being the maximum recommended dose in
millilitres.
Sterility (2.2.11). Complies with the test for sterility as described in general chapter on Radiopharmaceutical
preparation. The injection may be released for use before completion of the test.
Storage. Store in a containers with adequate shielding. Store at 2 to 80.
Expiry date –
Three days if RAC > 20 mCi per ml (from reference date)
Seven days if RAC <15 mCi per ml (from reference date)
Labelling. The label states in addition to the information specified under injections (1) the name, time and date
of Calibration (2) the amount of 153Sm as total megabecquerels (millicuries) and concentration as
megabecquerels (millicuries) per ml at the time of calibration (3) the expiration date (4) the statement
“Caution—Radioactive Material.”