Carbimazole

Carbimazole is an imidazole antithyroid agent under a class of drugs known as pro-drugs. It is considered a pro-drug because it converts to methimazole after being absorbed by the body, generating an antithyroid action that works against hyperthyroidism (excessive production of thyroid hormones) and thyrotoxicosis (inflammation of the thyroid gland).

Carbimazole is sold under different brand names, which include Atirozidina, Basolest, CG1, Carbimazol Spofa, Carbotiroid, Mertiran, Neo-Mercazole, Neo-Theyreostat, Neo-Tireol, Neomercazole and Tyrazol, among others. It is generally indicated for hyperthyroidism, when preparing a patient for thyroidectomy (surgical removal of all or part of the thyroid gland), or used together with radio-iodine therapy in cases of hyperthyroidism.

Hyperthyroidism occurs when the thyroid gland produces an excessive amount of T3 (triiosdothyronine) or T4 (thyroxine) hormones. The thyroid hormones regulate our metabolism, and too many thyroid hormones in the body will speed up the rate of metabolism, including the digestion and cardiovascular functions. Symptoms of hyperthyroidism include palpitations, intolerance for heat, insomnia, breathing difficulties, frequent bowel movement, fatigue, weight loss, warm moist skin, muscle weakness, hair loss, trembling hands, and light or absent menstrual periods.

Iodine is one of the prime elements in the formation of thyroid hormones. Carbimazole works by preventing iodine from coming together with other components to form thyroid hormones. This action decreases thyroid function by reducing the thyroid gland's production of thyroid hormones. The effects of Carbimazole are usually felt within three to four weeks of treatment, as the body will need to use up the thyroid hormones already existing before the medication was started.

Patients who suffer from hyperthyroidism need to inform their doctor if they are allergic to Carbimazole or any of its ingredients. If they experience any allergic reactions during treatment, drug intake should be stopped immediately until further medical advise. Patients who are pregnant should use Carbimazole with extreme caution, and only if the benefits of taking the medication outweighs the risk of harming the unborn child. As Carbimazole passes into breast milk, doctors do not recommend breastfeeding while taking this drug as it might inadvertently harm the nursing infant.

People who are taking Carbimazole may experience side effects like headaches, pruritus (itching), nausea, blood disorders, diarrhea, constipation, nausea, vomiting and stomach aches, myalgia (muscle pain), arthralgia (joint pain), jaundice (yellowing of the skin), hair loss, and a skin rash.

One serious side effect is a decrease in the bone marrow's production of blood cells, also known as bone marrow suppression. If this is accompanied by signs of an infection like a fever, a sore throat or mouth ulcers, the condition is considered serious and will need immediate medical attention.

The patient may experience some or all of the side effects associated with taking Carbimazole. However, if other side effects become apparent, they should consult their doctor immediately.

Carbimazole is manufactured in pink, circular 20 and 5 mg. tablets. Doctors will usually prescribe a gradually reduced dosage just enough to control the condition. A higher dosage of Carbimazole may result in an enlargement of the thyroid gland.

Carbimazole has the following structural formula:

Review published on: 09 April 2008