Sodium Iodide, i-123

Capsules: Each capsule contains 3.70 MBq (100 microCi) at time of calibration. Half of each capsule is white, while the other half is either pink, yellow, orange, grey or green according to the manufactured lot. The capsule will yield 2.03, 1.11, 0.61, or 0.33 MBq (55, 30, 16.5, or 9 microCi) according to the color-coded decay calendar which assigns a color and capsule activity for each week of the year. http://www.draximage.com/data/PDF/118_en.pdf

Table 2 below displays the (5) weeks activity of the capsule starting from the calibration day.

Certain drugs and iodine-containing foods interfere with the accumulation of radioiodide by the thyroid. Review the patients history, current medications, and recent diagnostic tests prior to the administration of Sodium Iodide I-131 Capsules Diagnostic. Advise patients to maintain a low-iodine diet two weeks prior to radioiodine administration and continue for several days during the uptake or imaging process and to discontinue the following products before they undergo the procedure as shown in Table 3:

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Mechanism of Action

Iodine is actively transported by the sodium-iodide symporter (NIS) protein, in thyroid follicular cells. Iodide is concentrated in follicular cells up to 50 times higher than in the plasma. Iodide is metabolically oxidized by thyroid peroxidase to iodinium (I+) which in turn iodinates tyrosine residues of thyroglobulin (tri or tetra-iodinated tyrosine). The gamma emission of Iodine I 131 is imaged or counted.

Pharmacokinetics

Absorption
Following oral administration of Sodium Iodide I 131 Capsules Diagnostic, 90% of the administered radioactivity of sodium iodide I 131 is systemically absorbed in the first 60 minutes.

Distribution
Following absorption, sodium iodide I 131 is distributed within the extra-cellular space. It is actively transported by the sodium-iodide symporter (NIS) proteinand binds to thyroglobulin resulting in accumulation in the thyroid. The thyroid uptake of iodide is usually increased in hyperthyroidism and in goiter, and is decreased in hypothyroidism. Sodium iodide I 131 also accumulates in the stomach, choroid plexus, salivary glands breast, liver, gall bladder, and kidneys.

Elimination
Metabolism
In thyroid follicular cells, iodide is oxidized through the action of thyroid peroxidase to iodinium (I+) which in turn iodinates tyrosine residues of thyroglobulin.

Excretion
Sodium iodide I 131 is excreted in urine and feces. The normal range of urinary excretion is 37% to 75% of the administered dose, varying with the thyroid and renal function of the patient. Fecal excretion is about 10%.

Administration Instructions

• Advise patients to hydrate before and after administration of Sodium Iodide I 131 Capsules Diagnostic and void frequently to ensure rapid excretion [see Dosage and Administration (2.2)].
• Advise patients to fast at least 2 hours before and 2 hours after administration to ensure absorption [see Dosage and Administration (2.2)].
• Advise patients to maintain a low-iodine diet two weeks prior to radioiodine administration and continue for several days during the uptake or imaging process [See Dosage and Administration (2.2) and Drug Interactions (7)].

Fetal Toxicity
Advise female patients of reproductive potential of the risk of neonatal hypothyroidism with fetal exposure [see Contraindications (4), Warnings and Precautions (5.1) and Use in Specific Populations (8.1, 8.3)].

Lactation
Advise women to discontinue breastfeeding after Sodium Iodide I 131 Capsules Diagnostic administration [see Use in Specific Populations (8.2)].

Manufactured by:
Jubilant DraxImage Inc., Kirkland, Québec, Canada, H9H 4J4.