Potassium iodate is indicated as a thyroid-blocking agent to prevent the uptake of radioactive iodine, for example after a nuclear accident.

For oral administration.

Administration should take place within 3 hours of a nuclear accident, or up to 10 hours after an accident, however, this is less effective.

A single daily dose should be administered. This will protect against exposure lasting up to 24 hours. (see Section 4.4).

For neonates living at home a dosage of ¼ tablet is satisfactory. The dosage can be crushed and mixed with milk or water.

For neonates in hospital a dosage of 12.5 mg iodine equivalent can be given as a standard solution freshly prepared from KI crystals. It is recommended that maternity wards store KI crystals.

For babies the dose may be crushed and mixed with milk or juice before administration. For children the dose may be crushed and mixed with eg. jam, honey or yoghurt.

Owing to the sensitivity of the neonate and foetus thyroid to large doses of iodine, repeated administration of stable iodine should be avoided for neonates and pregnant and lactating women.

• Hypersensitivity to the active substance, to iodine or to any of the excipients listed in section 6.1

• Renal failure

• Hypocomplementaemic vasculitis

• Dermatitis herpetiformis.

In cases of exposure to radioiodine from nuclear accidents, dosing of potassium iodate should be based on emergency plans and predetermined operational intervention levels. Risk benefit of administration of stable radioiodine should be considered for the different age groups at risk. Pregnant and lactating women, neonates, infants and children should be treated first. A single dose of potassium iodate gives adequate protection for one day. Prolonged exposure may require repeat dosing, however repeat dosing in the neonate, and in pregnant and lactating women should be avoided (see section 4.2). Iodine prophylaxis is used against inhaled radioiodine and should not be the main prophylaxis for ingested contamination.

Patients with thyrotoxicosis treated medically, or patients with a past history of thyrotoxicosis treated medically who are now off treatment and apparently in remission, may be at risk.

Iodine induced hyperthyroidism may be precipitated in patients with asymptomatic nodular goitre or latent Graves` disease, who are not under medical care.

Potassium salts should be given cautiously to patients with renal or adrenal insufficiency, acute dehydration or heat cramp.

Care should be exercised if potassium salts are given concomitantly with potassium-sparing diuretics, as hyperkalaemia may result (see section 4.5).

The potential benefit of iodine prophylaxis is greatest in the young. The thyroid of the foetus, neonate and young infant has a higher yearly thyroid cancer risk per unit dose of radioactive iodine than the thyroid of an adult.

Potassium iodate prophylaxis is not usually indicated in adults over 40 unless doses to the thyroid from inhalation rise to levels threatening thyroid function, that is of the order of about 5 Gy. The risk of thyroid cancer is extremely low in this group whereas the incidence of thyroid disease is higher in this group therefore the risk of iodine induced thyroid complications are higher.

Neonates in the first days of life are at particular risk from exposure to radioactive iodine and blocking of thyroid function by overload of potassium iodate. The fraction of radioactive uptake is fourfold greater than all other age groups. The neonatal thyroid is especially sensitive to functional blocking caused by overload of potassium iodate. Transient hypothyroidism during this early period of brain development can result in loss of intellectual capacity. If stable iodine is given to neonates close follow up of thyroid function is essential. For neonates who have been administered potassium iodate in the first few weeks of life TSH levels and, if necessary, T4 levels should be monitored and appropriate replacement therapy given.

Several drugs, such as captopril and enalapril can cause hyperkalaemia and this effect may be enhanced if Potassium Iodate is also administered.

The effect of quinidine on the heart is increased by increased plasma concentration of potassium.

Hyperkalaemia results from the interaction between potassium salts and potassium sparing diuretics such as amiloride or triamterene or aldosterone antagonists (see section 4.4).

The effects of iodine and iodides on the thyroid may be altered by other compounds which may also have an effect on the thyroid, including amiodarone and lithium. The hypothyroid and goitrogenic effects of lithium carbonate and iodides can be additive if they are given concurrently.

Teratogenic effects such as congenital goitre and hypothyroidism have been reported when iodides are administered to pregnant women.

Prophylactic administration of iodate to the pregnant mother should be effective for the foetus also.

Throughout pregnancy the number of doses of potassium iodate should be kept to a minimum and repeat doses should be avoided (see section 4.2). In areas of iodine deficiency prolonged dosage could lead to maternal or foetal thyroid blockage with possible consequences for foetal development. If potassium iodate is administered late in pregnancy, the thyroid function of the new-born should be monitored. This is generally met by routine screening in the neonatal period. For neonates who have been administered potassium iodate in the first few weeks of life TSH levels and, if necessary, T4 levels should be monitored and appropriate replacement therapy given.

Pregnant women with active hyperthyroidism must not take potassium iodate because of the risk of foetal thyroid blockage.

Iodine is actively transported into breast milk, however those breast feeding should continue to do so (see Section 5.2). Lactating women should avoid repeat doses (see section 4.2).

No effect.

Undesirable effects are listed by MedDRA System Organ Classes.

Assessment of undesirable effects is based on the following frequency groupings:

Very common: ≥ 1/10

Common: ≥ 1/100 to <1/10

Uncommon: ≥ 1/1,000 to <1/100

Rare: ≥ 1/10,000 to <1/1,000

Very rare: <1/10,000

Not known: cannot be estimated from the available data

Experience with potassium iodate is limited.The following side effects can occur with potassium iodide.

Hypersensitivity reactions such as skin rashes, swollen salivary glands, headache and bronchospasm can be mild or severe and may be dose dependent.

Hyperthyroidism, iodine induced autoimmunity (Grave's and Hashimoto type), toxic nodular goitre and iodine-induced hypothyroidism have been reported as side effects of iodine therapy.

An overactive thyroid gland, thyroiditis, and an enlarged thyroid gland with or without development or myxoedema have also been reported.

Continued administration may lead to mental depression, nervousness, sexual impotence and insomnia.

Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via:

Yellow Card Scheme

Tel: Freephone 0808 100 3352

Website: www.mhra.gov.uk/yellowcard

In overdose, symptoms of iodism such as headache, pain and swelling of the salivary glands, fever or laryngitis, swelling or inflammation of the throat, gastrointestinal upset and diarrhoea can occur. Pulmonary oedema, retinal toxicity, gastrointestinal bleeding, intravascular haemolysis, disseminated intravascular coagulation, and methaemoglobinaemia can also occur.

Acute ingestion of iodine can result in corrosive injury of the gastrointestinal tract and renal damage. Cardiopulmonary collapse due to circulatory failure should be treated by maintenance of airway and stabilisation of the circulation. Oedema of the glottis resulting in asphyxia or aspiration pneumonia can occur.

Gastric lavage should not be considered due to the possibility of corrosive injury. Activated charcoal is unlikely to adsorb iodates. Give milk or starch-based food.

Pharmacotherapeutic group: Antidotes, ATC code: V03AB

The iodine released from iodide and iodate on absorption from the gut is taken up rapidly and preferentially by the cells of the thyroid gland. Once in the thyroid, it is rapidly incorporated into organic molecules that are synthesised into thyroid hormones and ultimately released into the general circulation.

If excessive amounts of stable iodate are administered to normal adults, the iodine uptake mechanism of the thyroid is saturated and little or no further iodine is taken up. This effectively blocks the uptake of radioactive iodine in the event of accidental exposure to radio-iodines.

Iodine absorbed from the gut is taken up rapidly and preferentially by the cells of the thyroid gland. Renal clearance of iodide/iodate is usually in the range of 30 to 50 ml of serum/minute, is closely related to glomerular filtration, and is little affected by the iodate load. Most radioiodine not taken up by the thyroid gland after a single oral bolus of iodate is excreted in the urine over the subsequent 48-hour period.

As much as a quarter of the iodine taken by the mother can be secreted in the milk within 24 hours. Potassium iodate can partially block transport of radioiodine in the milk. The same criteria should apply when selecting a dose of potassium iodate to protect a lactating mother as that used for other young adults under 40 years of age.

Preclinical information has not been included because the safety profile of Potassium Iodate has been established after many years of clinical use.

Calcium Hydrogen Phosphate

Croscarmellose Sodium

Microcrystalline Cellulose

Magnesium Stearate.

None known.

Do not store above 25° C.

Store in original container.

In polypropylene containers with caps or child resistant closures in packs of 50, 100, 500 or 1000 tablets.

Blister strips in multiples of 6, 10 or 100 tablets.

Not all pack sizes may be marketed.

Not applicable.