rubidium chloride rb 82 - Generic Medications

11.1 Generator Characteristics CardioGen-82 (rubidium Rb 82 generator) contains accelerator-produced Sr 82 adsorbed on stannic oxide in a lead-shielded column and provides a means to produce sterile nonpyrogenic Rubidium Chloride Rb 82 Injection, a radioactive diagnostic agent, for intravenous use. 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 eluted at a rate of 50 mL/minute, each generator eluate at the end of elution should not contain more than 0.02 microCi of Sr 82 and not more than 0.2 microCi of Sr 85 per mCi of Rubidium Chloride Rb 82 Injection, and not more than 1 mcg of tin per mL of eluate. 11.2 Nuclear 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 krypton 82 (Kr 82). Table 5. Principal Radiation Emission Data for Rb 82 Radiation Mean Percent Per Disintegration Mean Energy (keV) Annihilation photons (2) 191.01 511 (each) Gamma rays 13-15 776.5 The specific gamma ray constant for Rb 82 is 6.1 R/hour-mCi at 1 cm. The first half-value layer is 0.7 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 lead. For example, the use of a 7.0 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 0.7 0.5 2.3 10 -1 4.7 10 -2 7.0 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 FractionRemaining Days FractionRemaining Days FractionRemaining 0* 1 15 0.660 30 0.435 1 0.973 16 0.642 31 0.423 2 0.946 17 0.624 32 0.412 3 0.920 18 0.607 33 0.401 4 0.895 19 0.591 34 0.390 5 0.871 20 0.574 35 0.379 6 0.847 21 0.559 36 0.369 7 0.824 22 0.543 37 0.359 8 0.801 23 0.529 38 0.349 9 0.779 24 0.514 39 0.339 10 0.758 25 0.500 40 0.330 11 0.737 26 0.486 41 0.321 12 0.717 27 0.473 42 0.312 13 0.697 28 0.460 14 0.678 29 0.448 *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 , 2.7 )].