Methimez (Methimazole 5mg) Tablets

Methimez general information

What is Methimez used for?

Lying either side of your windpipe at the base of your neck sits a small but important gland, the thyroid gland that produces thyroid hormone.  Thyroid hormone, also known as thyroxine, plays a vital role in controlling your body’s metabolism, as well as its growth and development.  Thyroid hormone regulates how your body uses energy, regulates body temperature, and metabolises nutrients, and it exists in two forms, levothyroxine or T4 and liothyronine or T3, which is the active form of thyroxine.  Thyroid hormone production is regulated by thyroid stimulating hormone (TSH), which is produced by the pituitary gland in the hypothalamus at the base of the brain.  If your thyroid gland produces too much thyroxine (hyperthyroid) or too little thyroid hormone (hyperthyroid), you will have a hormone imbalance that causes a range of symptoms.  Methimez tablets 5mg are a hyperthyroidism medication used to treat an overactive thyroid.  

Hyperthyroidism

Hyperthyroidism is a thyroid disease caused by an over-active thyroid, producing more thyroid hormone than you need, which causes thyrotoxicosis.  Grave’s Disease is the most common cause of an overactive thyroid.  It is an autoimmune disease, which means that your immune system attacks your own body’s cells by producing autoantibodies against your thyroid cells.  Antibodies are proteins that latch on to specific cells, usually harmful invading cells and pathogens, and help the immune cells destroy those cells, but if they turn on your body’s own cells, this can have disastrous effects. 

Grave’s Disease, an inherited autoimmune disease, is the most common form of hyperthyroidism.  The immune system turns on your own thyroid cells and makes autoantibodies called thyroid-stimulating immunoglobulins that lock onto the cell receptor for Thyroid Stimulating Hormone (TSH).  This stimulates thyroid cells to produce thyroid hormone continually.  In response, the thyroid gland grows in size, forming a lump in the neck known as a goitre.

Hyperthyroidism can also have other causes including inflammation, a tumour, or a virus infection; also, some medications can be the cause of an overactive thyroid. 

Symptoms

Symptoms of hyperthyroidism are caused by having too much thyroid hormone circulating in the bloodstream, which results in an increased rate of metabolism.  Symptoms include nervousness, restlessness, irritability, difficulty concentrating, rapid heartbeat, being oversensitive to heat, increased perspiration, difficulty sleeping, hand tremors, losing weight without trying, feeling hungry and an increased appetite, frequent bowel movements, and constant feelings of tiredness and weakness.  If left untreated, hyperthyroidism can lead to more serious health complications, including problems with the heart, eyes, bones and fertility.  It can also lead to problems during pregnancy.

Treating hyperthyroidism with Methimez

Hyperthyroidism treatment with Methimez tablets 5mg is suitable for relieving symptoms of thyrotoxicosis caused by having too much thyroid hormone and inducing permanent remission from symptoms.  It is also an effective treatment to restore normal thyroid function before thyroid surgery to remove the whole or a part of the thyroid gland, if a large goitre has developed.  Another treatment for hyperthyroidism is radioactive iodine to kill the thyroid cells, as iodine is used for the production of thyroid hormone.  Methimez tablets 5mg are used before and after radioactive iodine therapy to restore normal function to an overactive thyroid. 

How does Methimez work?

Methimez tablets 5mg contain methimazole, which used to treat hyperthyroidism to reduce high levels of thyroid hormone.  Methimazole in Methimez tablets 5mg is the active form of the drug carbimazole, and is described as an anti-thyroid drug as it works by inhibiting the action of thyroid peroxidase, which is an essential enzyme for the synthesis of thyroid hormone.  It also blocks the uptake of iodine into thyroid hormone, which is necessary for the production of active thyroid hormone.  This combined action of methimazole suppresses the production of thyroid hormone by the thyroid and helps restore normal levels of thyroid hormone and normal function to the thyroid gland.

What does Methimez contain?

Methimez tablets 5mg contain the active ingredient methimazole, an antithyroid medication used to treat hyperthyroidism to reduce high levels of thyroid hormone.

What are the side effects of Methimez?

Most medications have some side effects, but they are not experienced by everyone.  Some side effects are commonly experienced when taking Methimez, but others are not so common, and you should discuss any problems or concerns with your primary care physician. 

Common side effects when taking Methimez include gastrointestinal upset, nausea, headache, dizziness, arthralgia (painful joints), skin rash, itching (pruritus), loss of taste paraesthesia (sensation of tingling, numbness).  Agranulocytosis and neutropenia (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?

Have a talk with your primary healthcare physician before taking Methimez so that you have a full understanding of what this medicine is for and how to use it.  There are some reasons for not taking a medication; these are called contraindications, and for Methimez, you should consider the following before taking Methimez:

• Have you ever had an unusual reaction or an allergy when taking Methimez?
• Are you pregnant or breastfeeding, you should discuss using Methimez with your doctor?
• Do you have any problems with your kidneys or your liver?
• Do you have a serious haematological (blood or bone marrow) condition 
• If you have a simple non-toxic goitre (swelling on the neck caused by enlargement of the thyroid gland), then Methimez is not a suitable treatment

What medications interact with Methimez?

Some medicines interact with Methimez tablets 5mg and may affect the way it works, or are affected by Methimez or increase side effects; you should discuss possible interactions with your primary care physician.  These may include vitamin K-dependant anticoagulants, agranulocytosis inducing drugs such as the antipsychotic clozapine and some non-steroidal antiinflammatories, theophylline for asthma. 

If other medications may interact with Methimez, your doctor will discuss these with you. 

How should Methimez be taken and for how long?

You should take your Methimez tablets 5mg swallowed whole with a glass of water with or without food, twice times daily at approximately 8-hour intervals, morning and evening.  This may be increased by your doctor to three times daily.  The dose you take, how often and for how long will depend on the severity of your condition and your doctor’s recommendation.  Also, 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.

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.