Methimazole (Methimazole) - Summary

METHIMAZOLE SUMMARY

METHIMAZOLE TABLETS, USP 5 mg and 10 mg    8645-02

Methimazole (1-methylimidazole-2-thiol) is a white, crystalline substance that is freely soluble in water.

Methimazole is indicated in the medical treatment of hyperthyroidism. Long-term therapy may lead to remission of the disease.

Methimazole may be used to ameliorate hyperthyroidism in preparation for subtotal thyroidectomy or radioactive iodine therapy.

Methimazole is also used when thyroidectomy is contraindicated or not advisable.

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NEWS HIGHLIGHTS

Published Studies Related to Methimazole

Comparison of methimazole and propylthiouracil in patients with hyperthyroidism caused by Graves' disease. [2007.06]
CONTEXT: Although methimazole (MMI) and propylthiouracil (PTU) have long been used to treat hyperthyroidism caused by Graves' disease (GD), there is still no clear conclusion about the choice of drug or appropriate initial doses. OBJECTIVE: The aim of the study was to compare the MMI 30 mg/d treatment with the PTU 300 mg/d and MMI 15 mg/d treatment in terms of efficacy and adverse reactions... CONCLUSIONS: MMI 15 mg/d is suitable for mild and moderate GD, whereas MMI 30 mg/d is advisable for severe cases. PTU is not recommended for initial use.

Continuous methimazole therapy and its effect on the cure rate of hyperthyroidism using radioactive iodine: an evaluation by a randomized trial. [2006.08]
BACKGROUND: A randomized clinical trial was performed to clarify whether continuous use of methimazole (MTZ) during radioiodine ((131)I) therapy influences the final outcome of this therapy... CONCLUSION: Continuous use of MTZ hinders an excessive increase of the thyroid hormones during (131)I therapy of hyperthyroid diseases. However, such a strategy seems to reduce the final cure rate, although this adverse effect paradoxically is attenuated by the concomitant reduction of the thyroid (131)I uptake.

Effect of long-term continuous methimazole treatment of hyperthyroidism: comparison with radioiodine. [2005.05]
OBJECTIVE: To investigate the long-term effects of continuous methimazole (MMI) therapy... CONCLUSION: Long-term continuous treatment of hyperthyroidism with MMI is safe. The complications and the expense of the treatment do not exceed those of radioactive iodine therapy.

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Clinical Trials Related to Methimazole

Methimazole to Treat Polymyositis and Dermatomyositis [Completed]
This study will test the safety and effectiveness of the drug methimazole in treating polymyositis and dermatomyositis-inflammatory muscle diseases causing weakness and muscle wasting. Although it is not known what causes of these diseases, abnormal immune function is thought to be involved. Recent studies indicate that methimazole, which has been used for many years to treat thyroid disease, may alter immune activity by affecting the interaction between white blood cells called lymphocytes and certain molecules on cell surfaces. This study will examine the effects of methimazole on immune activity and muscle strength in patients with inflammatory muscle diseases and evaluate the drug side effects.

Patients with polymyositis and dermatomyositis who have normal thyroid function may be eligible for this study [age requirement?]. Candidates will undergo a history and physical examination; blood and urine tests; chest X-ray; muscle strength testing, daily living skills questionnaire, and speech and swallowing evaluation; magnetic resonance imaging of muscles; and muscle biopsy (removal of a small piece of muscle tissue under local anesthetic). When indicated, some candidates may also have cancer screening tests (for example, mammogram, Pap smear), a lung function test to measure breathing capacity, or an electromyogram, in which small needles are inserted into a muscle to measure the electrical activity .

Participants will take 30 mg of methimazole by mouth twice a day for 6 months. They will have blood tests weekly for the first 2 weeks and then every other week for the rest of the study to measure blood counts and liver and thyroid function. Blood will also be drawn for white blood cell studies during the screening evaluation, at the beginning of therapy, 6 to 12 weeks after therapy starts, at the end of the 6-month treatment period, and 1 and 3 months after therapy ends. Muscle enzyme and urine tests will be done once a month.. During drug treatment, patients will have periodic physical examinations and blood and muscle function tests to evaluate the response to therapy.

Antithyroid Drugs During Radioiodine Therapy [Completed]
Background: The use of radioactive iodine (131I) therapy as the definite cure of hyperthyroidism is widespread. According to a survey on the management of Graves’ disease, thirty per cent of physicians prefer to render their patients euthyroid by antithyroid drugs (ATD) prior to 131I therapy. This strategy is presumably chosen to avoid 131I induced ‘thyroid storm’, which, however, is rarely encountered. Several studies have consistently shown that patients who are treated with ATD prior to 131I therapy have an increased risk of treatment failure. Mostly, patients with Graves’ disease have been studied, while other studies were addressed also toxic nodular goiter. Thus, it is generally accepted that ATD have ‘radioprotective’ properties, although this view is almost exclusively based on retrospective data and is still under debate (13). Indeed, this dogma was recently challenged by two randomized trials in Graves’ disease, none of which showed such an adverse effect of methimazole pretreatment. It cannot be excluded that the earlier results may have been under influence of selection bias, a source of error almost unavoidable in retrospective studies. Whether ATD is radioprotective also when used in the post 131I period has also been debated. In the early period 131I therapy following a transient rise in the thyroid hormones is seen which may give rise to discomfort in some patients. The continuous use of ATD during 131I therapy leads to more stable levels of the thyroid hormones. By resuming ATD following 131I therapy, euthyroidism can usually be maintained until the destructive effect of 131I ensues. Nevertheless, many physicians prefer not to resume ATD, probably due to reports supporting that such a strategy reduces the cure rate. Parallel to the issue of ATD pretreatment, the evidence is based on retrospective studies and the ideal set-up should be reconsidered. To underscore the importance of performing randomized trials we showed recently that resumption of methimazole seven days after 131I therapy had no influence on the final outcome.

Aim: To clarify by a randomized trial whether continuous use of methimazole during radioiodine therapy influences the final outcome of this therapy, in a comparison with a regime in which methimazole as mono-therapy is discontinued 8 days before radioiodine.

Patients and Methods: 80 consecutive patients suffering from recurrent Graves’ disease or a toxic nodular goiter are included. All patients are rendered euthyroid by methimazole (MMI) and randomized either to stop MMI eight days before 131I or to continue MMI until four weeks after 131I. Calculation of the 131I activity (max. 600 MBq) includes an assessment of the 131I half-life and the thyroid volume. Patients are followed for one year with close monitoring of the thyroid function.

Block-Replacement Therapy During Radioiodine Therapy [Recruiting]
Background: The use of radioactive iodine (131I) therapy as the definite cure of hyperthyroidism is widespread. According to a survey on the management of Graves’ disease, thirty per cent of physicians prefer to render their patients euthyroid by antithyroid drugs (ATD) prior to 131I therapy. This strategy is presumably chosen to avoid 131I induced ‘thyroid storm’, which, however, is rarely encountered. Several studies have consistently shown that patients who are treated with ATD prior to 131I therapy have an increased risk of treatment failure. Mostly, patients with Graves’ disease have been studied, while other studies were addressed also toxic nodular goiter. Thus, it is generally accepted that ATD have ‘radioprotective’ properties, although this view is almost exclusively based on retrospective data and is still under debate. Indeed, this dogma was recently challenged by two randomized trials in Graves’ disease, none of which showed such an adverse effect of methimazole pretreatment. It cannot be excluded that the earlier results may have been under influence of selection bias, a source of error almost unavoidable in retrospective studies. Whether ATD is radioprotective also when used in the post 131I period has also been debated. In the early period 131I therapy following a transient rise in the thyroid hormones is seen which may give rise to discomfort in some patients. The continuous use of ATD during 131I therapy, possibly in combination with levothyroxine (BRT: block-replacement therapy), leads to more stable levels of the thyroid hormones. By resuming ATD following 131I therapy, euthyroidism can usually be maintained until the destructive effect of 131I ensues. Nevertheless, many physicians prefer not to resume ATD, probably due to reports supporting that such a strategy reduces the cure rate. Parallel to the issue of ATD pretreatment, the evidence is based on retrospective studies and the ideal set-up should be reconsidered. To underscore the importance of performing randomized trials we showed recently that resumption of methimazole seven days after 131I therapy had no influence on the final outcome.

Aim: To clarify by a randomized trial whether BRT during radioiodine therapy of hyperthyroid patients influences the final outcome of this therapy, in a comparison with a regime in which methimazole as mono-therapy is discontinued 8 days before radioiodine.

Patients and Methods: Consecutive patients suffering from recurrent Graves’ disease (n=50) or a toxic nodular goiter (n=50) are included. All patients are rendered euthyroid by methimazole (MMI) and randomized either to stop MMI eight days before 131I or to be set on BRT. This latter medication continues until three months after 131I. Calculation of the 131I activity (max. 600 MBq) includes an assessment of the 131I half-life and the thyroid volume. Patients are followed for one year with close monitoring of the thyroid function.

Rituximab in the Treatment of Graves' Disease [Completed]
Aim:

In a phase II pilot study encompassing 20 patients with Graves’ disease to evaluate the effect of rituximab:

1. Biochemically as assessed by markers of disease activity ( free T4, free T3, TSH, TSH-receptor antibodies, anti-TPO)

Pilot Study to Determine Radioiodide Accumulation and Dosimetry in Breast Cancers Using 124I PET/CT [Recruiting]
This is a pilot imaging study for women whose tumors express NIS [Na+I- symporter, sodium iodide symporter]. Eligibility is limited to the presence of strong (3+) and/or plasma membrane staining in > 20% of cells as determined by immunohistochemical methods. A total of 10 patients will be imaged with 124I PET/CT (serial scans over 24 hour period) to determine radioiodide uptake and distribution in tumor tissue. Thyroid iodide uptake and retention will be blocked beginning one week prior to 124I PET/CT scan with thyroid hormone (T3) and methimazole (impedes organification). Tumor, organ and whole body dosimetry will be calculated in each patient.

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PATIENT REVIEWS / RATINGS / COMMENTS

Methimazole review by 35 year old female patient
		Rating
Overall rating:
Effectiveness:		Highly Effective
Side effects:		No Side Effects
		Treatment Info
Condition / reason:		GRAVE'S DISEASE
Dosage & duration:		10 MG taken once daily for the period of 1 1/2 YRS.
Other conditions:		NONE
Other drugs taken:		NONE
		Reported Results
Benefits:		ALL SYMPTOMS SUBSIDED - SWOLLEN ANKLES, RESTLESS SLEEP, FEELING OVERHEATED/SENSITIVITY TO WARM TEMPERATURES, SHAKEY HANDS, SWOLLEN THYROID GLAND, HIGH THYROID LEVEL IN BLOOD TESTS, TIRED EYES, AND INCREASED APPETITE.
Side effects:		NONE.
Comments:		INITIALLY TOOK 10MG TWICE A DAY. AFTER 6 MONTHS, REDUCED TO ONCE A DAY. AFTER ONE YEAR, REDUCED TO 1 EVERY OTHER DAY OR SO. WHEN BLOOD TESTS CONSISTENTLY RESULTED IN NORMAL THYROID LEVELS, STOPPED TAKING METHIMAZOLE ALTOGETHER. I'VE BEEN IN REMISSION NOW FOR 1 YR.

Methimazole review by 50 year old female patient
		Rating
Overall rating:
Effectiveness:		Highly Effective
Side effects:		Severe Side Effects
		Treatment Info
Condition / reason:		Hyperthyroidism
Dosage & duration:		Varies 10-30 mgs taken 2-3 x per day for the period of 6 years
Other conditions:		Rapid and drastic weight loss and muscle loss and rapid heart rate.
Other drugs taken:		Calcium
		Reported Results
Benefits:		Stabilizes my thyroid function and brings it into a "normal" range. Consequently my heart rate normalizes
Side effects:		Early in treatment Drs. would give me a specific dose to take for as long as 6 weeks. During this amount of time, on say..30-20 mgs per day, my thyroid would become so enlarged, I could barely swallow.. I now have a better handle on it.. and monitor my self with either breaking pills or smaller doses which I can control. ALSO--I now have Osteopenia.
Comments:		First need to say Drs. waned me to have thyroid ablation. I opted to "keep" my thyroid and treat with mediycation, rather than "killing it off" chemically and becoming HYPO-Thyroid and treating with a replacement "synthroid" type meds. Early in treatment Drs. would give me a certain dose to take for as much as 6 weeks-long after reaching "normal" (tsh etc..)thyroid levels, Now I monitor myself by how I feel and usually I'm not accurate, but most of the time I am. ALSO I now have Osteopenia-exercise and calcium and Vit D are all very important!