Thysat 65 Mg Tablets
1.
NAME OF THE MEDICINAL PRODUCT
ThySat 65 mg tablets
2 QUALITATIVE AND QUANTITATIVE COMPOSITION
Each tablet contains 65.00 mg potassium iodide equivalent to 50.00 mg iodine. For a full list of excipients, see section 6.1.
3. PHARMACEUTICAL FORM
Tablet
The tablets are white to yellowish slightly marbled round tablets, with a smooth surface without any defects, cross-scored for ease of breaking.
The tablet can be divided into equal quarters.
4 CLINICAL PARTICULARS
4.1 Therapeutic indications
Potassium iodide is indicated as a thyroid-blocking agent to prevent the uptake of radioactive iodine, for example after a nuclear accident or during a nuclear medicine investigation before administering a radioiodinated compound, which is metabolised to iodide or which contains radioiodine impurities.
4.2 Posology and method of administration
Posology Nuclear accident
Iodine prophylaxis should be performed in case of a nuclear accident, when radioactive iodine is released, in all people involved including children and pregnant and breastfeeding women located in the endangered area. People with known iodine sensitivity or with a history of active treatment of thyroid disorders should consult their physician. When the nuclear accident is announced the required doses of potassium iodide are as follows:
Neonates up to 1 month of age: Quarter of a tablet = 16 mg potassium iodide equivalent to 12.5 mg iodine.
Children from 1 month to 3 years of age: Half a tablet = 32 mg potassium iodide equivalent to 25 mg iodine.
Children from 3 to 12 years of age: 1 tablet = 65 mg potassium iodide equivalent to 50 mg iodine.
Children from 12 years of age, adults and elderly: 2 tablets = 130 mg potassium iodide equivalent to 100 mg iodine.
Neonates will not require further doses. Pregnant and breastfeeding women should take a maximum of two doses.
A single daily dose should be administered. This will protect against exposure lasting up to 24 hours (see Section 4.4).
For children the medicine may be crushed and mixed with milk, water or juice before administration.
Nuclear medicine investigation
When ThySat 65 mg tablets are used as a blocking agent before administering a radioiodinated compound, which is metabolised to iodide or which contains radioiodine impurities, an oral dose of 130 mg (2 tablets) in adults will reduce thyroid uptake to less than 1% of normal. This dose should be administered on or before the day of the investigation and then daily until the estimated activity of radioiodine in the body has fallen to appropriate levels.
In children of 3 to 12 years 50% of the adult dose should be given and in children of 1 month to 3 years the dose should be 25% of the adult dose.
Potassium iodide should not be given when radioiodine is being administered for the purpose of diagnostic imaging or treatment of the thyroid gland.
Method of administration
For oral administration.
4.3 Contraindications
Hypersensitivity to iodine preparations (see also Sections 4.2 and 4.5) or to any of the excipients listed in section 6.1
4.4 Special warnings and precautions for use
In cases of exposure to radioiodine from nuclear accidents, dosing of potassium iodide 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 iodide 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 potassium-sparing 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 iodide 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.
Paediatric Population
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 iodide. 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 iodide. 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 iodide 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 iodide 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
Pregnancy
Teratogenic effects such as congenital goitre and hypothyroidism have been reported when iodides are administered to pregnant women.
However, in the event of a nuclear accident, the proper use of potassium iodide in low doses, over a short period of time, as a thyroid blocking agent is not contra-indicated. Prophylactic administration of iodide to the pregnant mother should also be effective for the foetus.
Throughout pregnancy the number of doses of potassium iodide 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 iodide 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 iodide 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 iodide because of the risk of foetal thyroid blockage.
Breast-feeding
Iodine is actively transported into breast milk, however those breast feeding should continue to do so (see Section 5.2).
Fertility
No human data on the effect of active substance potassium iodide on fertility are available. There is no preclinical information available on the effect of the active substance potassium iodide on mating or fertility.
4.7 Effects on ability to drive and use machines
ThySat 65 mg tablets have no or negligible influence on the ability to drive and use machines.
4.8 Undesirable effects
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 MHRA website: 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.
PHARMACOLOGICAL PROPERTIES
5
5.1 Pharmacodynamic properties
Pharmacotherapeutic group: Antidotes ATC code: V03AB21 Potassium iodide
When exposed to radioactive iodine, potassium iodide prevents damage by radioactive iodine to the thyroid gland due to saturation by non-radioactive iodine of thyroid gland preventing the uptake of radioactive iodine from contaminated air, water, milk and other foods. In the case of nuclear accident, it is necessary to administer potassium iodide within one hour! Administration within one hour results in the thyroid gland being saturated with nonradioactive iodine (more than 85%). For every hours’ delay the percentage of saturation decreases: after three hours the saturation with non-radioactive iodine is 50%. Administration of the iodine after six hours of exposure is of no benefit. Therefore, it is very important that public notice of possible nuclear accident is given as soon as possible.
5.2 Pharmacokinetic properties
The human body contains 20 to 50 mg of iodine. The average daily consumption is 150 to 200 pg. Iodine uptake by the thyroid gland is 80-fold higher compared with other organs. The human body is able to metabolise doses even manyfold higher than the daily recommended dose, mainly via urine, enterohepatic circulation and salivary glands (after the administration of one single dose of 3 g potassium iodide the dose is completely eliminated after 75 hours, 89% via urine).
As much as a quarter of the iodine taken by the mother can be secreted in the breast milk within 24 hours. Potassium iodide can partially block transport of radioiodine in the milk. The same criteria should apply when selecting a dose of potassium iodide 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 iodide has been established over many years of clinical use.
6.1 List of excipients
Cellulose, microcrystalline
Talc
Macrogol 6000
Silica, colloidal anhydrous
6.2 Incompatibilities
Not applicable.
6.3 Shelf life 6 years
6.4 Special precautions for storage
Do not store above 25°C.
Keep the blister in the outer carton in order to protect from light and moisture.
6.5 Nature and contents of container
Blister (white, opaque PVC/PVDC foil / Al foil with printing), package insert leaflet, outer paper folder.
Size of packing: 4, 10 or 100 tablets
Not all pack sizes may be marketed.
6.6 Special precautions for disposal
Any unused medicinal product or waste material should be disposed of in accordance with local requirements.
7 MARKETING AUTHORISATION HOLDER
hameln pharmaceuticals ltd, Nexus, Gloucester Business Park, Gloucester, GL3 4AG, UK
8 MARKETING AUTHORISATION NUMBER(S)
PL 01502/0082
9. DATE OF FIRST AUTHORISATION/RENEWAL OF THE AUTHORISATION
Date of first authorisation: 25/11/2011
10 DATE OF REVISION OF THE TEXT
19/01/2016