Methimazole Brands and Dosages Available in India for Hyperthyroidism Treatment
In India, methimazole is available under various brand names with dosages typically ranging from 5-20 mg tablets, and it is commonly prescribed for hyperthyroidism treatment.
Available Brands and Formulations
Based on the available evidence, methimazole is marketed in India under several brand names. While specific brand information for India is limited in the provided evidence, methimazole is generally available in the following formulations:
- Tablet forms (most common): 5 mg, 10 mg, and 20 mg strengths
- Typically available as immediate-release formulations
Dosing Recommendations
Initial Dosing
- Standard initial dose: 10-40 mg daily, depending on severity of hyperthyroidism 1
- Mild to moderate hyperthyroidism: 10-15 mg as a single daily dose 2
- Severe hyperthyroidism: 30-40 mg daily, which may be divided 3
Maintenance Dosing
- Once euthyroidism is achieved (typically within 4-8 weeks), dose can be reduced to 2.5-5 mg daily for maintenance therapy 4
- Single daily dosing is as effective as divided doses and has fewer side effects 2
Clinical Considerations
Efficacy
- Studies show that 77.5% of patients respond to 10 mg daily within 6 weeks, while 92.6% respond to 40 mg daily within the same timeframe 3
- The main factors determining response to methimazole are daily dose, pretreatment T3 levels, and goiter size 3
Pregnancy Considerations
- Propylthiouracil is preferred in the first trimester due to potential teratogenicity with methimazole
- Methimazole is preferred in the second and third trimesters due to lower risk of hepatotoxicity compared to propylthiouracil 1
Monitoring
- Thyroid function tests (TSH, FT4) should be checked every 2-4 weeks initially until stable 1
- The goal is to maintain FT4 or FTI in the high-normal range using the lowest possible dose 1
Side Effects to Monitor
- Major concern: Agranulocytosis (presents with sore throat and fever)
- Other potential adverse effects: hepatitis, vasculitis, thrombocytopenia 1
- Lower doses (15 mg daily) are associated with fewer side effects than higher doses (30 mg daily) 2
Treatment Duration
Long-term continuation of low-dose methimazole (2.5-5 mg daily) beyond the standard 12-18 months of therapy has been shown to be effective and safe in preventing recurrent hyperthyroidism 4.
Practical Prescribing Tips
- Start with a lower dose in elderly patients or those with mild disease
- Higher doses are appropriate for patients with large goiters or severe hyperthyroidism
- Single daily dosing improves patient compliance and has similar efficacy to divided doses
- Monitor for signs of agranulocytosis (sore throat, fever) and advise patients to seek immediate medical attention if these occur
Remember that methimazole has a half-life of 3-5 hours but concentrates in the thyroid gland, exerting effects for periods exceeding those in which serum concentrations can be measured 5.