Methimez (Methimazole 5mg) Tablets

Methimez general information

What is Methimez used for?

Methimez tablets 5mg are used to treat hyperthyroidism or over-active thyroid, which causes thyrotoxicosis due to over production of thyroid hormone.  The most common form of hyperthyroidism is Grave’s Disease or goitre, which is thought to be an autoimmune disease where autoantibodies called thyroid stimulating immunoglobulins bind to the receptor for Thyroid Stimulating Hormone (TSH) and cause loss of regulation of thyroid hormone production.  Hyperthyroidism can also be caused by inflammation, a tumour or a virus infection.  Symptoms of hyperthyroidism are due to increased production of thyroid hormone, which causes increased rate of metabolism.  They include nervousness, restlessness, irritability, difficulty concentrating, tiredness, rapid heartbeat, heat intolerance, increased perspiration, difficulty sleeping, hand tremors, weight loss, increased appetite, frequent bowel movements, and muscular weakness.  Methimez tablets 5mg are used to help induce permanent remission from thyrotoxicosis; also to restore normal thyroid function before thyroid surgery to remove whole or part of the thyroid gland; also before and after treatment with radioactive iodine for overactive thyroid.  Methimez tablets 5mg are not used for a simple non-toxic goitre in which the thyroid may not make enough thyroid hormone but otherwise functions normally. 

How does Methimez work?

Methimez tablets 5mg contain methimazole, which is the active form of carbimazole, and is a metabolite used reduce high levels of thyroid hormone.  Hyperthyroidism is due to an overactive thyroid gland and overproduction of thyroid hormone, which exists in two forms, thyroxine or levothyroxine, also known as T₄ and liothyronine or L-triiodothyronine also known as T₃.  The production of thyroid hormone is normally regulated by thyroid stimulating hormone (TSH), a hormone produced by the pituitary gland in the hypothalamus, at the base of the brain, and it is this regulation that is deficient in Grave’s disease.  Methimazole in Methimez tablets 5mg works by inhibiting the action of thyroid peroxidase, which is important in the synthesis of thyroid hormone and this blocks the production of thyroid hormone and thereby helps restore normal levels of thyroid hormone.   

What does Methimez contain?

Methimez tablets 5mg contain the active ingredient methimazole that is used to treat hyperthyroidism to restore normal levels of thyroid hormone.

Treating hyperthyroidism with Methimez

Methimez tablets 5mg contain methimazole that is used to treat hyperthyroidism to restore normal levels of thyroid hormone.  Overproduction of thyroid hormone causes hyperthyroidism, and the most common of form is Grave’s Disease or goitre that is thought to be an autoimmune disease, where autoantibodies called thyroid stimulating immunoglobulins bind to the receptor for Thyroid Stimulating Hormone (TSH).  Thyroid hormone exists in two forms, thyroxine or levothyroxine, also known as T₄ and liothyronine or L-triiodothyronine also known as T₃.  The production of thyroid hormone is normally regulated by TSH, a hormone produced by the pituitary gland in the hypothalamus, at the base of the brain, and it is this regulation that is deficient in hyperthyroidism.  Methimazole in Methimez tablets 5mg blocks the production of thyroid hormone, which helps restore normal levels of thyroid hormone and relieves symptoms of hyperthyroidism.  These include nervousness, restlessness, irritability difficulty concentrating, tiredness, rapid heartbeat, heat intolerance, increased perspiration and difficulty sleeping, hand tremors, weight loss, increased appetite, frequent bowel movements, and muscular weakness.

What are the side effects of Methimez?

The most commonly reported side effects when taking Methimez tablets 5mg include gastrointestinal upset, nausea, headache, dizziness, paraesthesia (sensation of tingling, numbness), arthralgia (painful joints), skin rash, itching (pruritus), loss of taste.  Agranulocytosis (reduced white cell count) is a possible serious side effect that should be monitored for symptoms like sore throat, bruising, bleeding, mouth ulcers, fever and malaise.

When should Methimez not be used?

You should not use Methimez tablets 5mg if you:

• are allergic to methimazole or any ingredients in Methimez
• are pregnant or are breastfeeding, without discussion with your doctor
• have liver disease
• have a serious haematological condition 
• have a simple non-toxic goitre (swelling on the neck caused by enlargement of the thyroid gland)
• are taking medicines that interact with Methimez including vitamin K-dependant anticoagulants, agranulocytosis inducing drugs, theophylline for asthma

What medications interact with Methimez?

Several medications interact with Methimez tablets 5mg and should either not be taken while you are taking Methimez or only after discussion and instruction from your doctor:

• Drugs that cause a serious reaction with Methimez: agranulocytosis inducing drugs
• Drugs that affect Methimez: theophylline for asthma
• Drugs that are affected by Methimez: vitamin K-dependant anticoagulants,

How should Methimez be taken?

You should take your Methimez tablets 5mg swallowed whole with a glass of water with or without food, 3 times daily at approximately 8-hour intervals.  The dose you take and for how long will depend on the severity of your condition and your doctor’s recommendation and your dose may be reduced depending on how well you respond.  You should see an improvement within three months, but you should continue to take your Methimez tablets 5mg for several months or years depending on your condition and your doctor’s recommendation.

How long should you take Methimez?

You should see an improvement within three months, but you should continue to take your Methimez tablets 5mg for several months or years depending on your condition and your doctor’s recommendation.

Missed dose of Methimez

If you miss a dose of Methimez tablets 5mg take it as soon as you remember, unless it is time to take the next dose, then skip the missed dose.  Do not take a double dose.

How should Methimez be stored?

You should store your Methimez tablets 5mg below 25°C in a cool dry place.