Tapazole (Methimazole) - Summary

TAPAZOLE SUMMARY

Tapazole^® (Methimazole Tablets, USP) is an orally administered antithyroid drug.

Each tablet contains 5 or 10 mg (43.8 or 87.6 µmol) of methimazole.

Tapazole is indicated in the medical treatment of hyperthyroidism. Long-term therapy may lead to remission of the disease. Tapazole may be used to ameliorate hyperthyroidism in preparation for subtotal thyroidectomy or radioactive iodine therapy. Tapazole is also used when thyroidectomy is contraindicated or not advisable.

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NEWS HIGHLIGHTS

Published Studies Related to Tapazole (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.

Serum thyrotropin-receptor autoantibodies levels after I therapy in Graves' patients: effect of pretreatment with methimazole evaluated by a prospective, randomized study. [2004.10]
OBJECTIVE: Radioiodine therapy (131I) in hyperthyroid Graves' disease is generally followed by a transitory increase in levels of thyrotropin receptors antibodies (TRAb). Immunosuppressive effects of antithyroid drugs are still a matter of debate. In this study we evaluated the effect of methimazole pretreatment on the TRAb boost induced by 131I. DESIGN: A randomized, prospective clinical trial... CONCLUSION: Methimazole pretreatment attenuates the 131I-induced rise in serum TRAb levels. The effects of methimazole could be attributed to a direct immunomodulatory action or may be due to its effects on the control of hyperthyroidism, which is a known cause of immune dysregulation.

Comparison of single daily dose of methimazole and propylthiouracil in the treatment of Graves' hyperthyroidism. [2004.06]
OBJECTIVE: The present study was to compare the efficacy of a single daily dose of methimazole (MMI) and propylthiouracil (PTU) in the treatment of Graves' hyperthyroidism. BACKGROUND: Antithyroid drugs, MMI and PTU, are widely used in the treatment of hyperthyroidism. Previous studies in the treatment of hyperthyroidism with a single daily dose of antithyroid drugs have demonstrated a more favourable result with MMI. However, the efficacy of a single daily dose of PTU was inconsistent. In this study, we examined the therapeutic efficacy of single daily doses of MMI and PTU on the change of thyroid hormones and thyrotropin receptor antibodies (TRAb) levels... CONCLUSION: During the 12-week treatment of Graves' hyperthyroidism, a single daily dose of 15 mg MMI was much more effective in the induction of euthyroidism than a single daily dose of 150 mg PTU. In the doses used in this study, MMI is preferable to PTU when a once-daily regimen of antithyroid drug is considered for the treatment of Graves' hyperthyroidism.

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Clinical Trials Related to Tapazole (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

Tapazole review by 49 year old female patient
		Rating
Overall rating:
Effectiveness:		Highly Effective
Side effects:		No Side Effects
		Treatment Info
Condition / reason:		hyperthyroidism
Dosage & duration:		20 mg taken once a day for the period of 3 months
Other conditions:		none
Other drugs taken:		none
		Reported Results
Benefits:		My hyperthyroidism is in remission 9 months after stopping the drug. I had no side effects and even my thyroid nodules are gone. Pretty amazing!!
Side effects:		None - I felt no different at all
Comments:		I took the tapazole daily along with atenolol for the shaking and heart racing I was experiencing. I am completely drug free for 9 months and the thyroid is fine. I am so glad I didn't let the doctors irradiate the gland to ablate it. I would have had to be on synthoid forever.