The thyroid gland uses iodine to produce thyroid hormones that regulate body metabolism. Thyroid agents either replace or remove hormones to prevent deficiency and excess. Thyroid agents include thyroid hormones (T3, T4, TSH)and antithyroid drugs (further classified as thioamides and iodine solution).
Adrenergic agonists are autonomic nervous system drugs that stimulate the adrenergic receptors of the sympathetic nervous system (SNS), either directly (by reacting with receptor sites) or indirectly (by increasing norepinephrine levels). An adrenergic agonist is also called a sympathomimetic because it stimulates the effects of SNS.