Drugs Similar to CARDIOGEN-82

11.1 Chemical Characteristics RUBY-FILL Rubidium Rb 82 Generator contains accelerator-produced Sr 82 adsorbed on stannic oxide in a lead-shielded column and provides a means for obtaining sterile non-pyrogenic solutions of rubidium Rb 82 chloride injection. The chemical form of Rb 82 is 82 RbCl. The amount (mCi) of Rb 82 obtained in each elution will depend on the potency of the generator. When used with the RUBY Rubidium Elution System, the generator provides ± 10% accuracy for rubidium Rb 82 chloride doses between 370 to 2220 MBq (10 to 60 mCi). When eluted at a rate of 15 to 30 mL/minute, each generator eluate at the end of elution should not contain more than 0.02 mcCi (0.74 kBq) of Sr 82 and not more than 0.2 mcCi (7.4 kBq) of Sr 85 per mCi of rubidium Rb 82 chloride injection, and not more than 1 mcg of tin per mL of eluate. 11.2 Physical Characteristics Rb 82 decays by positron emission and associated gamma emission with a physical half-life of 75 seconds. Table 5 shows the annihilation photons released following positron emission which are useful for detection and imaging studies. The decay modes of Rb 82 are: 95.5% by positron emission, resulting in the production of annihilation radiation, i.e., two 511 keV gamma rays; and 4.5% by electron capture, resulting in the emission of “prompt” gamma rays of predominantly 776.5 keV. Both decay modes lead directly to the formation of stable Kr 82. TABLE 5 Principal Radiation Emission Data Radiation Mean Percent Per Disintegration Mean Energy (keV) Annihilation photons (2) 191.01 511 (each) Gamma rays 13 to 15 776.5 The specific gamma ray constant for Rb 82 is 6.33 R cm 2 / mCi h (1.23 × 10 -12 C m 2 / kg MBq s). The first half-value layer is 0.53 cm of lead (Pb). Table 6 shows a range of values for the relative attenuation of the radiation emitted by this radionuclide that results from interposition of various thicknesses of Pb. For example, the use of a 6.15 cm thickness of Pb will attenuate the radiation emitted by a factor of about 1,000. TABLE 6 Radiation Attenuation by Lead Shielding Shield Thickness (Pb) cm Attenuation Factor 0.53 0.5 1.68 10 -1 3.55 10 -2 6.15 10 -3 9.3 10 -4 Sr 82 (half-life of 25 days; 600 hrs.) decays to Rb 82. To correct for physical decay of Sr 82, Table 7 shows the fractions that remain at selected intervals after the time of calibration. TABLE 7 Physical Decay Chart: Sr 82 half-life 25 days Days Fraction Remaining Days Fraction Remaining Days Fraction Remaining 0* 1.000 21 0.559 41 0.321 1 0.973 22 0.543 42 0.312 2 0.946 23 0.529 43 0.304 3 0.920 24 0.514 44 0.295 4 0.895 25 0.500 45 0.287 5 0.871 26 0.486 46 0.279 6 0.847 27 0.473 47 0.272 7 0.824 28 0.460 48 0.264 8 0.801 29 0.448 49 0.257 9 0.779 30 0.435 50 0.250 10 0.758 31 0.423 51 0.243 11 0.737 32 0.412 52 0.237 12 0.717 33 0.401 53 0.230 13 0.697 34 0.390 54 0.224 14 0.678 35 0.379 55 0.218 15 0.660 36 0.369 56 0.212 16 0.642 37 0.358 57 0.206 17 0.624 38 0.349 58 0.200 18 0.607 39 0.339 59 0.195 19 0.591 40 0.330 60 0.189 20 0.574 * Calibration time To correct for physical decay of Rb 82, Table 1 shows the fraction of Rb 82 remaining in all 15 second intervals up to 300 seconds after time of calibration [see Dosage and Administration ( 2.6 )].