Sodium Iodide (Sup131/Supi)

What it is and how it works

Sodium iodide I-131 is absorbed orally and actively taken up by the thyroid via the sodium–iodide symporter, in the same way as stable iodide. Iodine-131 emits beta particles that destroy functioning thyroid tissue and gamma radiation that allows imaging and uptake measurement.

Indications

Treatment of hyperthyroidism (Graves’ disease, toxic nodular goitre); ablation of thyroid remnants and treatment of differentiated thyroid carcinoma and its metastases; diagnostic thyroid uptake measurement and scintigraphy (low activities).

Dosage and administration (summary)

Given orally as capsules or solution in a nuclear medicine facility; the activity is individualised according to the indication, thyroid uptake and protocol.

Contraindications

Pregnancy and breast-feeding; hypersensitivity. Capsules are not suitable for patients with dysphagia, oesophageal stricture or gastrointestinal obstruction.

Warnings and precautions

Antithyroid drugs, iodine-containing medicines, contrast media and high dietary iodine reduce uptake and should be stopped beforehand according to protocol; a low-iodine diet is often advised. Adverse effects include hypothyroidism, radiation thyroiditis, sialadenitis and transient bone-marrow suppression after high activities; Graves’ ophthalmopathy may worsen (corticosteroid cover may be needed). Radiation-protection precautions must be followed, and pregnancy should be avoided for at least 6 months after treatment.

Pregnancy

Contraindicated; pregnancy must be excluded before administration.

Storage and supply

Store according to the manufacturer’s instructions in lead shielding, in compliance with national radiation-protection regulations.

Source: reference summary prepared from the EU SmPC/EPAR, BNF and WHO Model Formulary. The approved product information in Iran governs.