Sodium iodide [123I] (Natrii iodidum [125I])

Pharmacodynamics Pharmacokinetics Indications Carefully Contraindications Dosing and Administration Side effects
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Included in the formulation
  • Sodium iodide, 123 I
    solution inwards 
    Radium Institute. VGKhlopina NGO, State Unitary Enterprise     Russia
    • АТХ:

       

    Pharmacodynamics:

    Radioactive iodine (123I: half-life 13.2 hours; the decay constant is 0.0533 h-1; type of decay - electron capture; emitted radiation: γ-radiation with an energy of 159 kev; the average number of emissions / decay is 0.83) is selectively captured by the thyroid gland, with the same intensity as the stable iodine, for the synthesis of thyroid hormones. Thus, it becomes possible to quantify and visualize the anatomical distribution of iodine in the gland tissues. Sodium [123I] iodide also accumulates in functioning nodes of papillary, follicular and mixed (papillary-follicular) cancer and in metastases, although to a lesser extent than in normal thyroid tissue. Physical characteristics of radiation 123I allow it to be used for repeated studies in a shorter time and to obtain a picture of the thyroid gland of a higher quality than when using an isotope 131I.

    Pharmacokinetics:

    Absorption from the gastrointestinal tract is high. Selectively concentrates and binds to thyrosyl residues of thyroglobulin in the thyroid gland; also accumulates, but in a free state, in a choroidal plexus,in the mucous membrane of the stomach, salivary glands, mucosa of the nasal cavity, lactating mammary glands; the remainder is dispensed in the extracellular fluid. Absorption kinetics 123I with the thyroid gland (in relation to the administered amount) on average after 2 hours - 14%, after 4 hours - 19%, after 24 hours - 27%. In euthyroid patients, 5-30% of the dose administered is concentrated in the thyroid gland for 24 hours, an effective half-life of 13 hours; the remaining part is distributed in the intercellular fluid with an effective half-life of 8 hours. Pyreoid half-life of the thyroid depot is 80 days (with euthyroidism), 5-40 days (with hyperthyroidism). It is mainly excreted by the kidneys (50-75% of the administered dose in euthyroid patients with a normal functional state of the kidneys for 48 hours), with feces and saliva (less than 2% of the administered dose).

    Dosimetric information (according to the International Commission on Radiation Safety, publication 53, absorbed doses are calculated after intravenous administration, while receiving additional stomach irradiation due to the presence of radioactive iodine in the secretion of the stomach and salivary glands, with an average half-life of the stay in the stomach absorbed dose for it walls increases by ~ 40% for 123I, while the dose for other tissues and organs is reduced by ~ 3% for 123I; concentrations 124I and 125I in preparations 123I can vary depending on the method of preparation, in addition, the ratio of isotopes varies with time; even with completely suppressed thyroid function it absorbs 0.5-2% of the dose, in these conditions the effective dose for an adult is 0.016-0.025 mSv [MBq] or 0.059-0.092 mSv / mCi) are presented below (Tables 1, 2).

    Indications:

    Scanning and scintigraphy of the thyroid gland (assessment of the functional state and topography of the thyroid gland for the diagnosis of dystyreosis and other thyroid diseases in adults

    ICD-10
    Contraindications:

    · Individual intolerance

    · Pregnancy and the period of breastfeeding

    · Simultaneous reception of iodine-containing, thyreblocking or radiocontrast preparations

    · Age under 18 years old

    Carefully:no data
    Pregnancy and lactation:

    Recommendations FDA category C. It is necessary to exclude the possibility of pregnancy in women of reproductive age. In the study of pregnant women, the risk and benefit should be correlated and the radiation burden minimized.It is not recommended for use in the period of breastfeeding.

    Dosing and Administration:

    Inside or in / in, the dosage is selected individually. Before use, the preparation is brought to the desired activity by the dilution method.

    Side effects:

    · Nausea and vomiting

    · Headache

    · Skin: itchy skin, skin rashes, allergic reactions.

    Overdose:

    Cases of overdose are not described. Treatment is symptomatic.

    Interaction:

    Amiodarone, antithyroid agents (thiomide derivatives or aromatic compounds), benzodiazepines, iodine-containing radiopaque agents, glucocorticoids, zobogenous products (eg cabbage, turnips), iodine-containing foods, iodine-containing agents, bromides containing traces of iodine, iodine, monovalent anions (for example, perchlorate, thiocyanate), pyrazolone derivatives (eg, phenylbutazone), salicylates, iodized table salt (in large amounts), sodium thiopental, blocking agents (for example, concentrated iodine solution, potassium iodide, potassium perchlorate), thyroid hormones (natural or synthetic) - the accumulation may decrease 123I.It is recommended to cancel these funds for the next period of time before the introduction of sodium [123I] iodide: several months for amiodarone, 1 week for glucocorticoids, 4 weeks for benzodiazepines, 2-4 weeks for intravascular injection of iodine-containing radiopaque agents, at least 4 weeks for radiocontrast agents for cholecystography, 2-4 weeks for iodine-containing drugs (vitamins, expectorants, antitussives and topical agents), 1-2 weeks for pyrazolone derivatives, 1 week for sodium thiopental, 4-6 weeks for thyroxine drugs, 2-3 weeks for triiodothyronine preparations.

    Antithyroid remedies - the recoil effect can develop with sudden withdrawal of antithyroid drugs with very high thyroid iodine uptake during the first 5 days. It is recommended to cancel antithyroid drugs 1 week before the introduction of sodium [123I] iodide. For studies of early absorption (15-30 min) in order to detect iodide (not distribution in the organ), therapy with thioamide drugs should not be interrupted.

    Salicylates (with prolonged use) can inhibit the functions of the thyroid gland. It should be canceled 1-2 weeks before the introduction of sodium [123I] iodide.A recoil effect may develop after salicylate cancellation with an increase in iodine uptake by the thyroid gland within 3-10 days.

    Special instructions:

    Study of the functional state and topography of the thyroid gland with the help of 123I is carried out no earlier than 1 month after the discontinuation of the intake of substances and Drugscontaining iodine or affecting iodine accumulating function of the thyroid gland. These include: stable iodine (including contact with the skin or mucous membranes), iodine and iodinated products, radiocontrast agents, iodine-containing multivitamin preparations, fluoride, bromine, triiodothyronine, thyroxine, thyroidin, 6-methylthiouracil and other similar antithyroid drugs, as well as pituitary, sex and corticosteroid hormones.

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