About Carbimazole Thyroid peroxidase inhibitors(thioamide),Sulfur-containing imidazole derivatives, Antithyroid. Mechanism of Action of Carbimazole It is a potent antithyroid drug which inhibits thyroid hormone synthesis. It binds to thyroid peroxidase and inhibits oxidation of iodide or iodotyrosil residues. It inhibits iodination of tyrosine residues in thyroglobulin and prevents coupling of iodothyrosine residues to form T3 and T4. Thyroid colloid depleted over time and blood levels of T3 &T4 are reduced