nephroscan - Medication Listings

11.1 Chemical Characteristics NEPHROSCAN is a sterile, single-dose kit for the preparation of Technetium Tc 99m Succimer Injection a radioactive diagnostic agent, for intravenous use. The active ingredient, succimer is meso-2,3-dimercaptosuccinic acid with a molecular weight of 182.22 g/mol. The chemical structure of succimer is shown below. Subsequent to radiolabeling with sodium pertechnetate Tc 99m, the active moiety technetium Tc 99m succimer is obtained in situ. Each vial contains 1 mg succimer, 0.1 mg ascorbic acid, 0.42 mg stannous (tin) chloride dihydrate, 0.02 mg hydrochloric acid and 0.2 mg sodium hydroxide as a white-yellowish to off-white lyophilized powder. In addition, after radiolabeling with sodium pertechnetate Tc 99m injection, each vial contains up to 1,480 MBq (40 mCi) of technetium Tc 99m succimer in 0.9% sodium chloride injection as a sterile, clear, and colorless solution. pH of the final solution is between 3 and 3.5. FDA approved pH specifications differ from USP. Chemical Structure 11.2 Physical Characteristics Technetium Tc 99m decays by isomeric transition with a physical half-life of 6.02 hours. The principal photon that is useful for detection and imaging studies is listed in Table 3. Table 3 Principal Radiation Emission Data for Technetium Tc 99m Radiation/ Emission Mean % / Disintegration Mean Energy (keV) Gamma 2 89.07 140.5 To correct for physical decay of this radionuclide, the fractions that remain at selected intervals after the time of calibration are shown in Table 4. Table 4 Physical Decay Chart for Tc 99m, half-life 6.02 hours Hours Fraction Remaining Hours Fraction Remaining 0 Calibration time 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 11.3 External Radiation The specific gamma ray constant for technetium Tc 99m is 0.78 R/hr-mCi at 1 cm. The first half value layer is 0.017 cm of Pb. 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. Table 5 displays the radiation attenuation by lead shielding. Table 5 Radiation Attenuation by Lead (Pb) Shielding Shield Thickness (Pb) mm Coefficient of Attenuation 0.02 0.5 0.08 0.1 0.16 0.01 0.25 0.001 0.33 0.0001