Indium In -111 Pentetreotide

DESCRIPTION Octreoscan ™ is a kit for the preparation of Indium In 111 Pentetreotide Injection, a radioactive diagnostic agent. It is a kit consisting of two components: 1) A 10-mL Octreoscan Reaction Vial which contains a lyophilized mixture of: (i) 10 mcg pentetreotide [N-(diethylenetriamine-N,N,N′,N″-tetraacetic acid-N″-acetyl)-D-phenylalanyl-L-hemicystyl-L-phenylalanyl-D-tryptophyl-L-lysyl-L-threonyl-L-hemicystyl-L-threoninol cyclic (2→7) disulfide], (also known as octreotide DTPA), (ii) 2 mg gentisic acid [2, 5-dihydroxybenzoic acid], (iii) 4.9 mg trisodium citrate, anhydrous, (iv) 0.37 mg citric acid, anhydrous, and (v) 10 mg inositol. Pentetreotide has the following structural formula: Prior to lyophilization, sodium hydroxide or hydrochloric acid may have been added for pH adjustment. The vial contents are sterile and nonpyrogenic. No bacteriostatic preservative is present. 2) A 10-mL vial of Indium In 111 Chloride Solution, which contains: 1.1 mL or 111 MBq/mL (3 mCi/mL) indium In 111 chloride in 0.02N HCl at time of calibration. The vial also contains ferric chloride at a concentration of 3.5 mcg/mL (ferric ion, 1.2 mcg/mL). The vial contents are sterile and nonpyrogenic. No bacteriostatic preservative is present. Indium In 111 Pentetreotide Injection is prepared by combining the two kit components ( see INSTRUCTIONS FOR THE PREPARATION OF INDIUM In 111 PENTETREOTIDE INJECTION ). Indium In-111 reacts with the diethylenetriaminetetraacetic acid portion of the pentetreotide molecule to form indium In 111 pentetreotide. The pH of the resultant Indium In 111 Pentetreotide Injection is between 3.8 and 4.3. No bacteriostatic preservative is present. The Indium In 111 Pentetreotide Injection is suitable for intravenous administration as is, or it may be diluted to a maximum volume of 3 mL with 0.9% Sodium Chloride Injection, USP, immediately before intravenous administration. In either case, the radiolabeling yield of Indium In 111 Pentetreotide Injection should be determined before administration to the patient. A method recommended for determining the radiolabeling yield is presented at the end of this package insert (see RECOMMENDED METHOD FOR DETERMINATION OF RADIOLABELING YIELD OF INDIUM In 111 PENTETREOTIDE INJECTION ). Structural Formula Physical Characteristics Indium In-111 decays by electron capture to cadmium-111 (stable) and has a physical half-life of 2.805 days (67.32 hours) ( see Table 2 ). From Radiopharmaceutical Internal Dosimetry Information Center, Oak Ridge Associated Universities, Oak Ridge, TN 37831-0117, February 1985. The principal photons that are useful for detection and imaging are listed in Table 1. Table 1. Principal Radiation Emission Data Kocher, David C., "Radioactive Decay Data Tables,” DOE/TIC-11026, 115 (1981). Radiation Mean Percent Per Disintegration Energy (keV) Gamma-2 90.2 171.3 Gamma-3 94.0 245.4 The specific gamma ray constant for In-111 is 3.21 R/hr-mCi at 1 cm . The first half-value thickness of lead (Pb) for In-111 is 0.023 cm. Selected coefficients of attenuation are listed in Table 2 as a function of lead shield thickness. For example, the use of 0.834 cm of lead will attenuate the external radiation by a factor of about 1000. Table 2. Radiation Attenuation by Lead Shielding Shield Thickness (Pb) cm Coefficient of Attenuation 0.023 0.5 0.203 0.1 0.513 0.01 0.834 0.001 1.12 0.0001 Table 3 lists fractions remaining at selected time intervals before and after calibration. This information may be used to correct for physical decay of the radionuclide. Table 3. Physical Decay Chart: Indium In-111, Half-life 2.805 Days (67.32 hours) Hours Fraction Remaining Hours Fraction Remaining -72 2.100 0 Calibration time 1.000 -60 1.854 3 0.970 -48 1.639 6 0.940 -36 1.448 12 0.885 -24 1.280 24 0.781 -12 1.131 36 0.690 -6 1.064 48 0.610