Camazol is the brand name of an antithyroid medicine called Carbimazole. Carbimazole can be found in the form of tablets and can be taken with or without food. It is used to treat hyperthyroidism. Hyperthyroidism is a condition in which there is an excessive amount of thyroid hormone being released into the bloodstream. Patients can experience symptoms of the following:
- Weight loss despite increased appetite
- Excessive sweating
- Heat intolerance
- Rapid heart rate
- Frequent bowel movements
Common causes of hyperthyroidism include:
- Grave’s Disease
- Functioning Adenoma & Toxic Multinodular Goiter
- Excessive intake of thyroid hormones
- Abnormal secretion of thyroid-stimulating hormone (TSH)
- Excessive iodine intake
Other than treatment for hyperthyroidism, carbimazole can also be used before thyroidectomy as a preparation phase. It can also be used for therapy post or before radioiodine treatment.
Mechanism of Action of Carbimazole
Carbimazole is metabolized into thiamazole which is responsible for the antithyroid action. Thiamazole blocks the thyroid hormone by inhibiting the organification of iodide & coupling of iodothyronine residue.
Side Effects of Carbimazole
The most common side effects of carbimazole are upset stomach, nausea, and hair thinning. It is known that carbimazole can also affect the liver and blood counts thus if you’re having the following symptoms you visit the doctor immediately:
- Yellow discoloration of the skin or eye (Jaundice)
- Dark-colored urine
- Loss of appetite
- Right upper abdominal pain
- Muscle pain
- Unexplained bruising or bleeding
- Signs of infection such as sore throat or mouth ulcer
- Feeling tired
It is contraindicated to take this medicine if the patient has a severe hepatic impairment, a pre-existing blood disorder, and a history of acute pancreatitis.
Dosage of Carbimazole
There are two methods in taking carbimazole known as the Titration Method or the Block & Replace Method. Depending on the control of the patients hormone level, the doctor will determine which method is suitable for each patient.
The titration method can be done with the start with the dose of 15-40 mg taken daily 2-3 times a day. After 4-8 weeks, the dose will be reduced to a lower maintenance dose of 5-15 mg taken once daily. The titration method is done to prevent the patient from the risk of over-treatment that can lead to hypothyroidism. The maintenance dose will be continued to 6 months or up to 18 months. Regular thyroid hormone monitoring is advised with adjustment of the dose to maintain a euthyroid state.
Block & Replace Method:
Started with the same dose as the titration method but after 4-8 weeks the doctor may prescribe to the patient levothyroxine which will be taken with carbimazole. The prescription of levothyroxine is done to avoid hypothyroidism during treatment. This will allow better control of thyroid hormone levels.
Carbimazole on Pregnancy
It is known that carbimazole can cross the placenta but with controlled dose range and thyroid status monitoring there has no evidence of neonatal abnormalities. Studies have shown that the incidence of congenital anomaly is greater in children born from mothers who have untreated hyperthyroidism.
There are cases of congenital malformation following the use of carbimazole such as cases of skull, renal, cardiovascular congenital defect, exomphalos, gastrointestinal malformation, umbilical malformation & duodenal atresia. It should be noted that carbimazole should be used in a case where it is not suitable for the use of propylthiouracil.
If carbimazole is used to treat hypothyroidism in pregnant women, the dose needs to be regulated & the lowest dose should be given. Discontinuation of the drug should be done 3 or 4 weeks prior to term to reduce the risk of neonatal complication. Hyperthyroidism in pregnant women should be treated carefully to reduce the risk of maternal and neonatal complications.