Potassium Iodide 65mg Tablets
Out of date information, search anotherSUMMARY OF PRODUCT CHARACTERISTICS
1 NAME OF THE MEDICINAL PRODUCT
Iosat 65mg tablets Potassium iodide 65mg tablets
2 QUALITATIVE AND QUANTITATIVE COMPOSITION
Each Iosat/Potassium iodide tablet contains 65mg potassium iodide, equivalent to 50mg iodine.
For the full list of excipients, see section 6.1.
3 PHARMACEUTICAL FORM
Tablet.
White rounded tablet of 5 mm diameter with “IOSAT” on one side and quadrasect on the other side.
4 CLINICAL PARTICULARS
4.1 Therapeutic indications
Iosat/Potassium iodide 65mg Tablets are used for thyroid iodine uptake blockade in nuclear accidents (to prevent accumulation of radioactive iodine (iodine 131) in the thyroid gland).
4.2 Posology and method of administration
Take only when instructed by a physician or the authorities.
The tablets can be swallowed or dissolved in a small amount of liquid before being taken. Potential irritation of the gastric mucosa can be avoided by drinking plenty of additional fluids. To obtain the correct dosage for children aged up to 36 months, a solution should be prepared using a whole tablet, and the required volume of solution given (see details later in this section on making a potassium iodide solution).
The iodine blockade achieved with doses in the order of 100 mg or more of iodide results in reduced uptake of radioactive iodine by the thyroid gland by a factor of 90 or more, provided that the tablets are taken promptly. If possible, the iodine tablets should be taken before any radioactive iodine uptake occurs. Satisfactory blockade can still be achieved provided the radioactive iodine uptake has occurred less than two hours previously. Iodine tablets can still reduce the amount of time for which radioactive iodine
remains in the body, even when taken several hours after the radioactive iodine uptake.
The tablets should however be taken for the first time no later than one day after radioactive iodine uptake, as otherwise its elimination is delayed.
|
Population/age group |
Dosage |
|
Pregnant and breast-feeding women: |
2 tablets (equivalent to 100 mg iodine) |
|
< 1 month: |
V tablet (equivalent to 12.5 mg iodine) |
|
1 to under 36 months: |
Vi tablet (equivalent to 25 mg iodine) |
|
3 to under 13 years: |
1 tablet (equivalent to 50 mg iodine) |
|
13 to under 45 years: |
2 tablets (equivalent to 100 mg iodine) |
|
Persons over 45 years: |
Tablet intake is not recommended |
A single dose is generally sufficient. In exceptional cases, the competent authorities or a physician will recommend that an additional tablet be taken. However, dosing must always be limited to 1 day for neonates and to 2 days for women who are pregnant or breastfeeding.
A solution of potassium iodide should be prepared in order to administer a partial-tablet dose to children under 36 months.
Making a Potassium Iodide Solution:
1. Put one tablet into a small bowl and grind it into a fine powder using the back of a metal teaspoon against the inside of the bowl. The powder should not have any large pieces.
2. Add 4 teaspoonfuls of water to the crushed potassium iodide powder in the bowl and mix until the powder is dissolved in the water.
For children < 1 month old, administer 1 teaspoonful.
For children from 1 to 36 months old, administer 2 teaspoonfuls
The dose may be given mixed with a small amount of flavoured drink in order
to make it more palatable for the child.
4.3 Contraindications
Iosat/Potassium iodide 65mg tablets must not be used in patients with: Hyperthyroidism of any aetiology
Known hypersensitivity to iodine (this is very rare and must not be confused with the
common allergy to x-ray contrast media) or to any of the excipients Duhring’s disease (dermatitis herpetiformis)
Hypocomplementaemic vasculitis
4.4 Special warnings and precautions for use
Use of Iosat/Potassium iodide 65mg tablets in patients > 45 years
In an iodine-deficient region where the incidence of autonomous thyroid function increases with age with an accompanying increase in the risk of side effects from iodine blockade, and where the risk of radiation-induced thyroid cancer is considerably reduced with advancing age, iodine blockade is not recommended for individuals aged over 45.
Special precautions for the use of Iosat/Potassium iodide 65mg tablets
Patients already under treatment with thyrostatic drugs must continue with this treatment and undergo medical examinations at frequent intervals.
The administration of iodine should generally be avoided in patients with suspected thyroid cancer.
Patients with Duhring’s dermatitis herpetiformis or genuine iodine allergy (allergies to x-ray contrast media are frequently not allergies to iodine but rather to the contrast medium itself) must not undergo iodine blockade. Because the extent of the reactions in each individual case cannot be predicted, the long-term and indeterminate risk of irradiation of the thyroid gland must be considered as being lower than the immediate and potentially severe consequences of an allergic reaction.
Administration of large quantities of iodine may cause an increase in the size of the thyroid gland which may in turn exacerbate any pre-existing severe tracheal compression.
If autonomous areas are left untreated, there is a risk of hyperthyroidism which may in the most extreme cases provoke a thyrotoxic crisis. Iodine tablets should not therefore be taken in these cases.
4.5 Interaction with other medicinal products and other forms of interaction
Thyrostatic agents required to treat hyperthyroidism would exhibit reduced efficacy when taken concomitantly with Iosat/Potassium iodide 65mg tablets.
Iodine uptake in the thyroid gland is competitively inhibited by substances which enter the thyroid via the same “trapping” mechanism as iodine (e.g. perchlorate, which also inhibits the recirculation of iodine within the gland), as well as by substances which are not themselves transported (such as thiocyanate at concentrations over 5 mg/dl).
4.6 Fertility, pregnancy and lactation
Pregnant and breastfeeding women are given the same dose of Iosat/Potassium iodide 65mg tablets as adolescents and adults (see section 4.2, Posology and method of administration). The duration of treatment for pregnant and breastfeeding women should be limited to two days.
4.7 Effects on ability to drive and use machines
Potassium iodide is not expected to impair concentration or reactions.
4.8 Undesirable effects
The following frequency convention was used as a basis for evaluating undesirable effects:
>1/10
Very common: Common: Uncommon: Rare:
Very rare:
> 1/100, < 1/10,
> 1/1,000, < 1/100,
> 1/10,000, < 1/1,000,
< 1/10,000, not known (cannot be estimated from the available data)
Gastrointestinal disorders
Common: Iosat/Potassium iodide 65mg tablets may cause irritation of the gastric mucosa, especially when taken on an empty stomach.
Endocrine disorders
Iosat/Potassium iodide 65mg tablets to prevent radioactive iodine accumulation may in isolated cases result in iodine-induced hyperthyroidism. In most cases, this is attributable to autonomous areas in the thyroid.
Vascular disorders
Rare: Periarteritis nodosa.
Immune system disorders
In rare cases, an undiagnosed iodine allergy may manifest itself for the first time when iodine tablets are taken. This may include general signs of allergy and in addition, due to increased secretion from the mucosa, itching and burning in the eyes, iodine-induced rhinitis, irritant cough, diarrhoea, headaches due to sinusitis, and other symptoms. Life-threatening reactions are possible, particularly in the case of preexisting Duhring’s dermatitis herpetiformis.
4.9 Overdose
a) Overdose:
The administration of very high doses of iodide may result in irritation of the skin and mucous membranes (e.g. gastroenteritis). In the event of potentially life-threatening symptoms, gastric lavage is indicated, possibly followed by administration of an isotonic sodium sulfate solution as a laxative.
b) Iodine-induced hypothyroidism:
Discontinue iodine and restore the metabolic balance by administration of thyroid hormones.
c) Iodine-induced hyperthyroidism:
This is not strictly speaking an overdose since hyperthyroidism can also be triggered by levels of iodine that are considered to be physiological in other countries.
Treatment appropriate to the form of hyperthyroidism should be given.
In certain circumstances, mild forms may not require any treatment, while more severe forms may require thyrostatic therapy (although this is slow to take effect). In the most severe cases (thyrotoxic crisis), intensive care, plasmapheresis or thyroidectomy are indicated.
5 PHARMACOLOGICAL PROPERTIES
5.1 Pharmacodynamic properties
Pharmacotherapeutic group: Antidote, potassium iodide.
ATC code: V03AB21
The effects of exogenous iodine administration on the human body depend on the daily iodine dose, the type of iodine product and the condition of the thyroid gland (healthy organ, latent disorder or manifest disorder). Pharmacologically effective iodine doses (over 1 mg/day) can trigger the following effects:
a) Wolff-Chaikoff effect. Excess iodine results in inhibition of organification in the thyroid gland. If this excessive iodine level persists, inhibition is superseded by reduced iodine uptake. Persistence of the Wolff-Chaikoff effect under pathological conditions results in hypothyroidism and the development of goitres.
b) Reduced intrathyroid iodine metabolism and colloid proteolysis and hence reduced hormone release. This effect is particularly marked in cases of hyperthyroidism, and is accompanied - in particular in patients with immunogenic forms of hyperthyroidism - by reduced perfusion, reduced size and induration of the thyroid gland.
5.2 Pharmacokinetic properties
Absorption
Iodine normally enters the body via the gastrointestinal tract. However, it is also absorbed percutaneously and from body cavities. Particular attention must be paid to this in cases of accidental iodine medication intake. Absorption of inorganic iodine in the small intestine is almost 100%; percutaneous absorption however is minimal and uncontrolled.
Distribution
The volume of distribution in healthy subjects averages 23 litres (38% of body weight). Serum levels of inorganic iodine are normally between 0.1 and 0.5 pg/dl.
In the body, iodide accumulates in the thyroid gland and in other tissues, such as the salivary glands, mammary glands and the stomach. Iodine stored within the thyroid has a half-life of 7 weeks.
Biotransformation
Elimination
The elimination of iodine in the urine, which is expressed in most cases as pg/g creatinine, is used as an indicator of iodine intake as it is in equilibrium with daily dietary iodine intake.
Linearity/non-linearity
Pharmacokinetic/pharmacodynamics relationship(s)
The iodide concentration in the saliva, gastric juices and breast milk is approximately thirty times the plasma concentration.
5.3 Preclinical safety data
Mutagenic and carcinogenic potential
There are no known studies investigating mutagenic and carcinogenic potential. There are no indications that iodine or iodide possess such properties.
Reproductive toxicity
There is no evidence of teratogenic effects from animal studies. Iodine crosses the placenta and may cause foetal hypothyroidism and/or goitre when administered to pregnant women at very high doses. Iodide is concentrated in and excreted in breast milk. When administered at very high doses, there is a risk of infants developing hypothyroidism. Limiting the use of potassium iodide tablets in pregnant and breastfeeding women to a maximum of 2 days counters the potential risks for the foetus and infant.
6 PHARMACEUTICAL PARTICULARS
6.1 List of excipients
Cellulose, microcrystalline Sodium thiosulfate Silica, colloidal anhydrous Magnesium stearate
6.2 Incompatibilities
None known.
6.3 Shelf life
5 years.
6.4 Special precautions for storage
Store in the original container to protect from light. Store below 30°C.
6.5 Nature and contents of container
Iosat/Potassium iodide 65mg tablets are supplied in blister strips in packs containing either 20 or 100 tablets.
Not all pack sizes may be marketed.
6.6 Special precautions for disposal
Any unused product or waste material should be disposed of in accordance with local requirements.
7 MARKETING AUTHORISATION HOLDER
Agropharm Limited IOSAT Division Buckingham Place,
Church Road, Penn,
High Wycombe, Bucks,
HP10 8LN, United Kingdom.
8 MARKETING AUTHORISATION NUMBER(S)
PL 10772/0001
9 DATE OF FIRST AUTHORISATION/RENEWAL OF THE AUTHORISATION
02/08/2012
10 DATE OF REVISION OF THE TEXT
23/07/2013