Treatment of Hyperthyroidism (2) The foundation of therapy lies in a reduction of thyroid hormone production using antithyroid drugs, partial thyroidectomy, or radioiodine therapy. Ancillary treatment, which reduces the peripheral manifestations of thyroid hormones, is sometimes employed using a b-adrenergic blocking drug such as propranolol, or drugs that impair the conversion of T4 to the biologically active T3, as well as blocking T4/T3 production (for example, propylthiouracil or ipodate). See later: • Antithyroid Drugs • Partial Thyroidectomy • Radioiodine Therapy