← Search & browse all drugs
SYSTEMIC HORMONAL PREPARATIONS, EXCL. SEX HORMONES AND INSULINS › THYROID THERAPY › ANTITHYROID PREPARATIONS › Thiouracils
methylthiouracil
H03BA01
Forms & Strengths
- Tablets: 5mg, 10mg
- Oral solution: 5mg/mL
Adult Dosing
- Initial dose: 5mg tid
- Maintenance dose: 5-15mg tid
- Maximum dose: 30mg/day
Pediatric Dosing
- Children under 12 years: not recommended
- 12-18 years: initial dose 2.5mg tid, titrate as needed
Indications
- Hyperthyroidism
- Thyrotoxicosis
- Graves' disease
Mechanism of Action
- Inhibits synthesis of thyroid hormones
- Specifically, blocks oxidation of iodine in thyroid gland
- Reducing T3 and T4 production
Contraindications
- Pregnancy (especially first trimester)
- Breastfeeding
- Hypersensitivity to methylthiouracil
Adverse Reactions
- Agranulocytosis
- Thrombocytopenia
- Vitamin B12 deficiency
- Hepatotoxicity
- Gastrointestinal upset
Drug Interactions
- Increases theophylline levels
- Reduces effectiveness of beta-blockers
- Interacts with warfarin, increasing INR
Curated Content: Needs Vetting Before Put to Clinical Use