Thyroid and antithyroid drugs

Thyroid hormones

Thyroid hormones are used in hypothyroidism (myxoedema), and also in diffuse non-toxic goitre, Hashimoto’s thyroiditis (lymphadenoid goitre), and thyroid carcinoma. Neonatal hypothyroidism requires prompt treatment for normal development. Levothyroxine sodium (thyroxine sodium) is the treatment of choice for maintenance therapy. In infants and children with congenital hypothyroidism and juvenile myxoedema, the dose of levothyroxine should be titrated according to clinical response, growth assessment, and measurements of plasma thyroxine and thyroid-stimulating hormone.

LEVOTHYROXINE SODIUM (Thyroxine sodium):

Indications: Congenital Hypothyroidism, Goiter, Hashimoto Thyroiditis, Hypothyroidism, Myxedema, and Thyroid Carcinoma.

Contraindications: Myocardial Infarction, Primary Adrenocortical Insufficiency, Thyrotoxicosis Crisis, Hyperthyroidism, And Pituitary Insufficiency.

Dose and Administration: adult, initially 50–100 micrograms once daily, preferably before breakfast, adjusted in steps of 25–50 micrograms every 3–4 weeks according to response (usual maintenance dose 100–200 micrograms once daily); in cardiac disease, severe hypothyroidism, and patients over 50 years, initially 25 micrograms once daily, adjusted in steps of 25 micrograms every 4 weeks according to response; usual maintenance dose 50–200 micrograms once daily.

Antithyroid drugs

Antithyroid drugs are used for hyperthyroidism either to prepare patients for thyroidectomy or for long-term management. Iodine has been used as an adjunct to antithyroid drugs for 10 to 14 days before partial thyroidectomy; however, there is little evidence of a beneficial effect. Iodine should not be used for long-term treatment because its antithyroid action tends. Propranolol is useful for rapid relief of thyrotoxic symptoms and may be used in conjunction with

antithyroid drugs or as an adjunct to radioactive iodine. Beta-blockers are also useful in neonatal thyrotoxicosis and in supraventricular arrhythmias due to hyperthyroidism. Propranolol has been used in conjunction with iodine to prepare mildly thyrotoxic patients for surgery but it is preferable to make the patient euthyroid with carbimazole.

CARBIMAZOLE:

Indications: hyperthyroidism either to prepare patients for thyroidectomy or for long-term management.

Contraindications: in patients with a previous history of adverse reactions.

Dose and Administration: the initial dose is in the range 20-60mg taken as two to three divided doses. Maintenance regimen the dose is gradually reduced.

PROPYLTHIOURACIL:

Indications: Hyperthyroidism, Thyrotoxicosis Crisis.

Contraindications: Agranulocytosis, Drug-Induced Hepatitis, Interstitial

Pneumonitis, Lactating Mother, Pancytopenia, and Pregnancy.

Dose and Administration: 50 mg by oral route 2 times per day.