Prescription Drug Name:

Sodium Iodide
I-123 Capsules






id: 0ABB3AE7-1E4F-44DF-B220-112BCAC83ADC
FDA Article Code: 34089-3

GE Healthcare (Medi-Physics, Inc.) Sodium Iodide I-123 for diagnostic use is supplied as capsules for oral administration. At calibration time, each capsule has an activity of 3.7 MBq (100 µCi) or 7.4 MBq (200 µCi). Each gelatin capsule contains not more than 20 µg of sodium hydroxide and not more than 1 g of sucrose. Each capsule also contains FD&C Yellow No. 6.Sodium Iodide I-123 is an odorless compound, freely soluble in water. The I-123 is produced in an accelerator by bombardment of enriched Xe-124 with protons [Xe-124 (p,2n) Cs-123Xe-123 I-123].The radionuclidic composition at calibration time is not less than 99.5% I-123 and not more than 0.5% all other nuclides (Te-121, I-125, I-131, I-126, I-124, I-130, I-121 and Na-24). The radionuclidic composition at expiration time is not less than 98.28% I-123 and not more than 1.72% all other nuclides (Te-121, I-125, I-131, I-126, I-124, I-130, I-121 and Na-24).Molecular formula: Na123IMolecular Weight: 145.99


id: DF3574C0-22D4-324E-9342-75AF3A72929C
FDA Article Code: 42229-5

Iodine-123 decays by electron capture with a physical half-life of 13.2 hours. The photon that is useful for detection and imaging studies is listed in Table 1.

Table 1. Principal Radiation Emission DataKocher, David C., Radioactive Decay Data Tables, DOE/TIC-11026, 122(1981)
Radiation Mean %/Disintegration Mean Energy (keV)
Gamma-2 83.4 159


id: 04E436E9-68F1-B673-9FF1-2B8783F7F43F
FDA Article Code: 42229-5

The specific gamma ray constant for I-123 is 11.2 µC/Kg-MBq-hr (1.6 R/hr-mCi) at 1 cm. The first half value thickness of lead (Pb) for I-123 is 0.005 cm. A range of coefficients of attenuation of the radiation emitted by this radionuclide can be achieved by the interposition of various thicknesses of Pb and is shown in Table 2. For example, the use of 1.63 cm of lead will decrease the external radiation exposure by a factor of about 1,000.

Table 2. Radiation Attenuation by Lead ShieldingMethod of Calculation: Data supplied by Oak Ridge Associated Universities, Radiopharmaceutical Internal Dose Information Center, 1984.
Shield Thickness (Pb) cm Coefficient of Attenuation
0.005 0.5
0.10 10-1
0.88 10-2
1.63 10-3
2.48 10-4
To permit correction for the physical decay of I-123, the fractions that remain at selected intervals after the time of calibration are shown in Table 3.
Table 3. Physical Decay Chart: Iodine-123, Half-Life 13.2 Hours
Hours Fraction Remaining
0Calibration Time 1.000
3 0.854
6 0.730
9 0.623
12 0.533
15 0.455
18 0.389
21 0.332
24 0.284


id: 22E30161-20A7-4FA3-6059-6B7088215B47
FDA Article Code: 34090-1

Sodium Iodide is readily absorbed from the upper gastrointestinal tract. Following absorption, the iodide is distributed primarily within the extracellular fluid of the body. It is concentrated and organically bound by the thyroid and concentrated by the stomach, choroid plexus, and salivary glands. It is also promptly excreted by the kidneys. The normal range of urinary excretion in 24 hours is reported to be 37-75% of the administered dose, varying with thyroid and renal function. The iodide concentrating mechanism of the thyroid, variously termed the iodide “trap” or “pump,” accounts for an iodide concentration some 25 times that of the plasma level, but may increase to as much as 500 times under certain conditions.“Trapped” iodide is oxidized to iodine and organically incorporated so rapidly that the trap contains less than 0.2% free iodide in comparison to organically bound iodine. This process results in a further concentration of iodine in the thyroid gland to about 500 fold that of blood. The iodinated organic compounds consist chiefly of thyroxine (T4) and triiodothyronine (T3), which are bound to thyroglobulin in the follicular colloid. The T4 and T3 are released by enzymatic proteolysis of thyroglobulin into the blood, where they are specifically bound and transported by plasma thyroid binding proteins. These reactions are mostly under the control of anterior-pituitary thyroid stimulating hormone (TSH) and hypothalamic thyroid releasing factor (TRF). Thyroid uptake is usually increased in hyperthyroidism and in goiter with impaired hormone synthesis. Uptake is usually decreased in hypothyroidism and normal or decreased in hyperthyroidism treated with iodide. It should be noted that the uptake of tracer iodine is a function of stable iodide concentration in the serum as well as of alterations in thyroid physiology.


id: 0965B1E5-C042-77C9-C570-8F94E00D6972
FDA Article Code: 34067-9

Sodium Iodide I-123 is indicated for use in the evaluation of thyroid function and/or morphology.


id: 887D37EC-E48A-E649-FF3C-9C744379B5FE
FDA Article Code: 34070-3

None known.


id: 6E183AD8-BA99-8A1D-3153-03324F094904
FDA Article Code: 34071-1

Females of childbearing age and pediatric patients under 18 should not be studied unless the benefits anticipated from the performance of the test outweigh the possible risk of exposure to the amount of ionizing radiation associated with the test.


id: 4C693F9A-082C-8EF6-0896-5C543D40ED93
FDA Article Code: 34084-4

Although rare, reactions associated with the administration of Sodium Iodide isotopes for diagnostic use include, in decreasing order of frequency: nausea, vomiting, chest pain, tachycardia, itching skin, rash and hives.Allergic type reactions have been reported infrequently following the administration of iodine-containing radiopharmaceuticals.


id: 08CDFC99-2972-8932-CC4A-805ADB983338
FDA Article Code: 34068-7

The recommended oral dose range for diagnostic studies of thyroid function in the average adult patient (70 kg) is 3.7-14.8 MBq (100-400 µCi) of Sodium Iodide I-123. The lower portion of the range 3.7 MBq (100 µCi) is recommended for uptake studies alone, and the higher portion 14.8 MBq (400 µCi) for thyroid imaging.Concentration of I-123 in the thyroid gland should be measured in accordance with standardized procedures. Consideration should be given to the use of proper instrumentation in thyroid imaging with Sodium Iodide I-123. The determination of I-123 concentration in the thyroid gland may be initiated at six hours after administration of the dose.Use contents of the capsule up to 24 hours after calibration time and date. Thereafter, discard the capsule with its contents. The user should wear waterproof gloves at all times when handling the capsule.The patient dose should be measured by a suitable radioactivity calibration system immediately prior to administration.


id: 4CEB1D3F-21C7-4456-B075-8B937FAE2CD3
FDA Article Code: 42229-5

The estimated absorbed radiation doses to several organs of an average patient (70 kg) from oral administration of 14.8 MBq (400 µCi) of I-123 supplied by GE Healthcare (Medi-Physics, Inc.), are shown in Table 4 for thyroid uptakes of 5, 15, and 25%.The figures in Table 4 represent the maximum possible absorbed radiation dose when the recommended dose of GE Healthcare (Medi-Physics, Inc.) Sodium Iodide I-123 is administered at calibration or at expiry.

Table 4. Radiation Dose Estimates for I-123 Sodium Iodide
Estimated Radiation Absorbed Dose
Maximum Thyroid Uptake (%) TOCConcentrations assumed by Oak Ridge for calculations:
  Time of Calibration: 99.5% I-123, 0.5% Te-121.
  Time of Expiry: 98.3% I-123, 1.7% Te-121.
Organ mGy
14.8 MBq
400 µCi
14.8 MBq
400 µCi
I-123 data supplied by Oak Ridge Associated Universities, Radiopharmaceutical Internal Dose Information Center, 1991.
Bladder (voiding interval = 4.8 hrs.) 5 1.4 0.14 1.5 0.15
15 1.3 0.13 1.4 0.14
25 1.2 0.12 1.3 0.13
Stomach Wall 5 0.98 0.098 1.0 0.10
15 0.91 0.091 0.96 0.096
25 0.83 0.083 0.89 0.089
Small Intestine 5 0.26 0.026 0.37 0.037
15 0.25 0.025 0.36 0.036
25 0.23 0.023 0.34 0.034
Liver 5 0.10 0.010 0.15 0.015
15 0.10 0.010 0.15 0.015
25 0.097 0.0097 0.15 0.015
Ovaries 5 0.22 0.022 0.34 0.034
15 0.21 0.021 0.32 0.032
25 0.20 0.020 0.31 0.031
Bone Surfaces 5 0.14 0.014 0.19 0.019
15 0.15 0.015 0.20 0.020
25 0.16 0.016 0.21 0.021
Red Marrow 5 0.10 0.010 0.15 0.015
15 0.10 0.010 0.16 0.016
25 0.10 0.010 0.16 0.016
Testes 5 0.11 0.011 0.19 0.019
15 0.094 0.0094 0.19 0.019
25 0.089 0.0089 0.18 0.018
Thyroid 5 9.5 0.95 9.5 0.95
15 29 2.9 29 2.9
25 51 5.1 51 5.1
Total Body 5 0.11 0.011 0.16 0.016
15 0.12 0.012 0.17 0.017
25 0.13 0.013 0.18 0.018


id: 366CCB27-970B-4FED-ADC1-F92D6B567848
FDA Article Code: 34069-5

Sodium Iodide I-123 capsules for oral administration are supplied as follows:Product No. 2031 – 3.7 MBq (100 µCi) – orange capsule – NDC 17156-201-05Product No. 2032 – 7.4 MBq (200 µCi) – orange/white capsule – NDC 17156-522-05At calibration time, each capsule has an activity of 3.7 MBq (100 µCi) or 7.4 MBq (200 µCi). Each gelatin capsule contains not more than 20 µg sodium hydroxide and not more than 1 g of sucrose. Each capsule also contains FD&C Yellow No. 6.This radiopharmaceutical is licensed by the Illinois Emergency Management Agency for distribution to persons licensed pursuant to 32 Ill. Admin. Code Section 330.260(c) and Section 335, Subpart D, 335.3010 and Subpart E, 335.4010 or under equivalent licenses of an Agreement State or a Licensing State.The single dose capsule is supplied with a desiccant in a plastic container that is enclosed in a labeled lead shield.One extra shield label is supplied with each single capsule for attachment to a shielded container other than the one in which the drug product is supplied. The capsule should be stored at room temperature below 30°C, 86°F. The expiration date has been determined to be 24 hours after calibration time and date.


id: DB8AFB74-671C-B7A7-2EB9-07EAF66776B0
FDA Article Code: 44425-7

Users should monitor the amount of radioactivity present prior to disposal of this product. Storage and/or disposal of Sodium Iodide I-123 should be in accordance with the conditions of Agreement State licenses and regulations, or other regulatory agency authorized to license the use of radionuclides.