Potassium Iodate 85 Mg Tablets
SUMMARY OF PRODUCT CHARACTERISTICS
1 NAME OF THE MEDICINAL PRODUCT
Potassium Iodate 85mg Tablets
2 QUALITATIVE AND QUANTITATIVE COMPOSITION
Each tablet contains 85mg Potassium Iodate equivalent to 50mg iodine.
For excipients see Section 6.1.
3 PHARMACEUTICAL FORM
Tablet.
White to off white round, biplanar tablet with cross scored breakline and a diameter of approximately 8 mm.
The tablet can be divided into equal doses.
4 CLINICAL PARTICULARS
4.1 Therapeutic indications
Potassium Iodate is indicated as a thyroid-blocking agent to prevent the uptake of radioactive iodine, for example after a nuclear accident.
4.2 Posology and method of administration
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).
Tablets Iodine equivalent
Adults, elderly and 2 tablets adolescents (over 12 years)
100mg
Children (3-12 years) 1 tablet 50mg
Children (1 month - 3 years) 'A tablet 25mg
Neonates (birth - 1 month) % tablet 12.5mg
or 12.5mg iodine equivalent as standard solution
For neonates living at home a dosage of % 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.
4.3 Contraindications
Potassium iodate is contra-indicated in patients with known iodine sensitivity, renal failure, hypocomplementaemic vasculitis or dermatitis herpetiformis.
4.4 Special warnings and precautions for use
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. 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 potassiumsparing diuretics, as hyperkalaemia may result.
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.
4.5 Interaction with other medicinal products and other forms of interaction
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.
4.6 Fertility, pregnancy and lactation
Teratogenic effects such as congenital goitre and hypothyroidism have been reported when iodides, and therefore presumably iodate, are administered to pregnant women.
However, in the event of a nuclear accident, the proper use of potassium iodate in low doses, over a short period of time, as a thyroid blocking agent is not contra-indicated. Prophylactic administration of iodate to the pregnant mother should also be effective for the foetus.
Throughout pregnancy the number of doses of potassium iodate should be kept to a minimum. 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 newborn 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).
4.7 Effects on ability to drive and use machines
No effect.
4.8 Undesirable Effects
Since experience with potassium iodate is limited, presumably the following side effects, which can occur with potassium iodide can also be associated with potassium iodate.
Hypersensitivity reactions such as skin rashes, swollen salivary glands, headache, bronchospasm and gastro-intestinal disturbances 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 the Yellow Card Scheme at: www.mhra.gov.uk/yellowcard
4.9 Overdose
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 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. In acute iodine poisoning large quantities of milk and starch mucilage should be given.
Lavage with starch mucilage or lavage with activated charcoal should be considered if there is no oesophageal damage.
Electrolyte and water losses should be replaced and the circulation should be maintained. Pethidine (100 mg) or morphine sulphate (10 mg) may be given for pain. A tracheostomy may become necessary.
Haemodialysis may reduce excessively elevated serum iodine concentrations.
Retinal toxicity has been associated with potassium iodate overdose.
5.1 Pharmacodynamic properties
Pharmacotherapeutic group: Antidotes, ATC code: V03A B21
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.
5.2 Pharmacokinetic properties
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.
5.3 Preclinical safety data
Preclinical information has not been included because the safety profile of Potassium Iodate has been established after many years of clinical use.
6 PHARMACEUTICAL PARTICULARS
6.1 List of excipients
The tablet contains:
Calcium Hydrogen Phosphate Dihydrate,
Croscarmellose Sodium Microcrystalline Cellulose Magnesium Stearate
6.2 Incompatibilities
None known.
6.3. Shelf life
30 months.
6.4 Special precautions for storage
Store in the original package.
6.5 Nature and contents of container
This medicinal product is packed in OPA/Aluminium/PVC- Aluminium blisters. Pack sizes: 10 or 100 tablets.
Not all pack sizes may be marketed.
6.6 Special precautions for disposal
Not applicable.
7 MARKETING AUTHORISATION HOLDER
Genus Pharmaceuticals Limited Linthwaite,
Huddersfield,
HD7 5QH, UK
8 MARKETING AUTHORISATION NUMBER(S)
PL06831/0275
9 DATE OF FIRST AUTHORISATION/RENEWAL OF THE AUTHORISATION
03/09/2013
10 DATE OF REVISION OF THE TEXT
08/12/2014