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1. Potassium Iodide 65mg Tablets
2. Potassium Iodide 65mg Tablets

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SUMMARY OF PRODUCT CHARACTERISTICS

1    NAME OF THE MEDICINAL PRODUCT

Potassium iodide 65 mg tablets

2    QUALITATIVE AND QUANTITATIVE COMPOSITION

1 tablet contains 65 mg potassium iodide, equivalent to 50 mg iodine.

Excipient with known effect:

Lactose monohydrate: 80 mg.

For the full list of excipients, see section 6.1.

3    PHARMACEUTICAL FORM

Tablet

Diameter: about 8.3 mm Thickness: 3.2 - 3.8 mm

White to brown-white, round, curved tablet with a pressure-sensitive cross break line on the inner side and notches on the outer side.

The tablet can be divided into equal quarters.

4    CLINICAL PARTICULARS

4.1    Therapeutic indications

For use after nuclear accidents with release of radioactive iodine isotopes to prevent the uptake of radioactive iodine in the thyroid after intake or inhalation of this substance.

Posology and method of administration

Iodine tablets may only be taken after explicit appeal by the authority, for example via radio or television.

It is recommended to use the tablets within one hour after announcement, however, beneficial effects are expected if the product is administered within two hours after exposure.

To be able to provide the proper doses for children more easily, the tablets have got a cross break score. The tablets may be chewed or swallowed whole. For newborns and babies, the dose may be grinded or dispersed in water, syrup or a similar liquid. It may take up to 6 minutes until the tablets are fully dispersed.

Adults and children above 12 years: 2 tablets Children from 3 to 12 years: 1 tablet Children from 1 month to 3 years: half a tablet Newborns and babies younger than a month: a quarter tablet Pregnant and breast-feeding women (all ages): 2 tablets Elderly patients

The intake of iodine tablets is not recommended for persons above 40 years because it has been determined that in this population there is no increased risk of thyroid cancer after exposition to radioactive iodine.

Special populations

No dosage adjustments are required in special populations such as patients with impaired renal or hepatic function. Iodine elimination occurs mainly via the kidneys; however, renal elimination rate is not influenced by iodine intake or iodine serum levels.

The above mentioned doses protect against a potential uptake of radioactive iodine after exposition by inhalation during the passing by of a radioactive plume.

If the release of radioactive iodine continues and thus also the exposure by inhalation, the above mentioned doses should be given on a daily basis as long as the release of radioactive iodine continues.

Pregnant and breast-feeding women should take two doses as a maximum. Newborns must not be given more than a single dose. Children developing skin reactions after the first intake must not receive further doses as well.

It is necessary to take the tablets as soon as possible to ensure thyroid saturation in cases of exposition to radiation. If taken 4 to 6 hours after the exposure to radioactive iodine, protection is approximately 50%. The intake is useless 12 hours after the exposure, because the thyroid has already taken up radioactive iodine.

4.3 Contraindications

Hypersensitivity to the active substance or to any of the excipients listed in section 6.1.

Dermatitis herpetiformis van Duhring Hyperthyroidism Hypocomplementaemic vasculitis

4.4 Special warnings and precautions for use

Patients undergoing thyreostatic treatment must continue with such therapy and regularly undergo medical examinations at short intervals.

If thyroid carcinoma is suspected, iodine administration should generally be avoided.

The administration of iodine interferes with radioiodine therapy and thyroid diagnostics.

Pharmacological doses of iodine may cause thyroid enlargement, which in turn may aggravate airway constriction.

Patients suffering from untreated thyroid autonomy may develop hyperthyroidism or thyreotoxicosis.

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 protects against inhaled or ingested radioiodine and has no effect on other ingested radionuclides.

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 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 is 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 iodide. The fraction of radioactive uptake is fourfold greater than in 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.

This medicine contains lactose. Patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption should not take this medicine.

4.5 Interaction with other medicinal products and other forms of interaction

Iodine administration interferes with radioiodine therapy and thyroid diagnostics (see section 4.4).

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.

Potassium salts given concomitantly with potassium-sparing diuretics such as amiloride or triamterene or aldosterone antagonists may cause hyperkalaemia (see section 4.4).

4.6 Fertility, Pregnancy and lactation

Pregnancy

Repeated administration of iodide during pregnancy may suppress foetal thyroid function. Reproductive toxicity has been established in animal studies. The intake must be limited to a maximum of 2 doses during pregnancy. If iodide is taken in late pregnancy it is recommended to monitor the thyroid function of the newborn.

Breast feeding

Iodide is being excreted into breast milk in large amounts, but these amounts are too small to protect the baby sufficiently. Thus the baby has to be given potassium iodide as well. If the intake during breast feeding is necessary, the intake has to be limited to a maximum of 2 doses (see section 4.2).

4.7 Effects on ability to drive and use machines

Not relevant.

4.8 Undesirable effects

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)

Immune system disorders

Not known: hypersensitivity reactions such as swollen salivary glands, headache, bronchospasm and gastro-intestinal disturbances can be mild or severe and may be dose dependent.

Endocrine disorders

Not known: 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.

Psychiatric disorders

Not known: Continued administration may lead to mental depression, nervousness, sexual impotence and insomnia.

Skin and subcutaneous tissue disorders Rare: temporary skin rash.

4.9 Overdose

Symptoms

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.

Newborns are particularly sensitive to iodine overload, probably by an immature regulation system. 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 (see also section 4.4).

Treatment

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.

5    PHARMACOLOGICAL PROPERTIES

5.1    Pharmacodynamic properties

Pharmacotherapeutic group: Antidotes, ATC code: V03AB21

In cases of a nuclear accident radioactive iodine may form a large amount of the output.

Because of its high volatility it can be easily inhaled and absorbed via the lungs.

Radioactive iodine can be detected in large amounts in the thyroid if exposed to very strong radiation, by which the risk for local damage is increased. The uptake of radioactive iodine by the thyroid can be blocked by saturation, by the early intake of a high dose of stable iodide. A dose of 130 mg (= 2 tablets) potassium iodide provides complete saturation. The risk for thyroid cancer due to exposition to radioactive iodine is higher in younger persons. Generally it is assumed that foetusses of more than 12 weeks, newborns and children have got the highest risk because their thyroid is still in growth.

5.2 Pharmacokinetic properties

Absorption

Orally administered iodine is converted in inorganic iodide and it is almost completely absorbed from the gastrointestinal tract. Food causes a delay of 10-15 minutes. Absorption is completed 2 hours after oral administration.

At intake on an empty stomach, radioactive ¹³¹I is detected in the neck area after about 3 minutes.

Physiological serum concentrations in humans vary from 1 to 5 pg/l (40 to 80 nmol/l) at daily iodine intakes of 150 to 250 pg.

Distribution

Iodine in the systemic circulation is being exchanged rapidly between erythrocytes and extracellular liquid. The total amount of inorganic iodide in this pool is about 250 Pg.

The uptake of iodide by the thyroid depends on volume, thyroid function, plasma iodide concentration and physiological age. Active iodide transport in extrathyroidal tissues such as salivary gland, lacrimal gland, choroid plexus, ciliary body of the eye, skin, placenta, gastric mucosa, and in mammary glands during lactation takes place to a minor extent

Iodine passes the placental barrier and is taken up by the foetal thyroid. It was found that uptake starts around a foetal age of 3 months. The highest concentration was found at a foetal age of about 6 months. In children and adolescents the iodine uptake by the thyroid is higher than in adults. In elderly persons, however, a significant reduction was observed.

If iodine doses are administered on an empty stomach, the half maximum thyroid uptake is reached after approximately 4 hours, although the duration is between 2.5 and 6.5 hours for most of the patients.

Biotransformation

Iodine undergoes organification in the thyroid, i.e. it is being oxidized and linked to thyroglobuline. The thyroid hormones thyroxine (T4) and triiodothyronine (T3) are being synthetized via oxidative condensation of the iodated intermediates monoiodotyrosine (MIT) and diiodotyrosine (DIT) inside the thyroglobuline complex. Hormone secretion takes place by way of pinocytosis followed by proteolytical release of T4 and T3 from thyroglobulilne.

Elimination

The main elimination (95%) occurs via the kidneys and amounts for approximately 30 to 40 ml/min.

Renal elimination rate is not influenced by iodine intake or iodine serum levels.

In pregnant women there is an increased elimination of iodide which may cause iodine deficiency.

Only small amounts of iodine have been found in faeces (approximately 1% of the total iodine elimination).

Iodine is being excreted into breast milk in considerable amounts (10-15% of the intake).

5.3 Preclinical safety data

A single high dose has been found to be teratogenic in rats. In another study in rats, the administration of high daily iodine doses led to incomplete parturition, failure of lactation and reduced mothering activities. The administration of a iodine-containing substance to pigs had no teratogenic effects.

In a long term study where rats received potassium iodide in the drinking water for two years the development of squamous cell carcinomas in the salivary glands were observed.

Apart from the information provided in the other sections, there is no additional relevant information from animal studies.

6    PHARMACEUTICAL PARTICULARS

6.1    List of excipients

Maize starch Lactose monohydrate Microcrystalline cellulose Basic butylated methacrylate copolymer Magnesium stearate (E 572)

6.2    Incompatibilities

Not applicable.