PPT_Chapter_32 - Thyroid and Antithyroid Drugs Chapter 32 Copyright \u00a9 2013 Wolters Kluwer Health | Lippincott Williams Wilkins Thyroid Thyroid is

PPT_Chapter_32 - Thyroid and Antithyroid Drugs Chapter...

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Unformatted text preview: Thyroid and Antithyroid Drugs Chapter 32 Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Thyroid Thyroid is located in the neck in front of the trachea. Manufactures and secretes two hormones: Thyroxine Triiodothyronine Iodine is essential for the manufacture of both hormones. Activity is regulated by thyroid-stimulating hormone (TSH), produced by the anterior pituitary gland. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Thyroid Two diseases are related to the hormone-producing activity of the thyroid gland: Hypothyroidism: a decrease in the amount of thyroid hormones manufactured and secreted Hyperthyroidism: an increase in the amount of thyroid hormones manufactured and secreted Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Thyroid Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Actions of Thyroid Hormones Both natural and synthetic hormones Synthetic are generally preferred because they are more uniform in potency than the natural hormones obtained from animals Influence every organ and tissue of the body Principally concerned with increasing the metabolic rate of tissues, which results in increases in the heart and respiratory rate, body temperature, cardiac output, oxygen consumption, and the metabolism of fats, proteins, and carbohydrates Exact mechanism by which they work is not understood Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Uses of Thyroid Hormones Replacement therapy when the patient is hypothyroid Levothyroxine is the drug of choice Relatively inexpensive Once-per-day dosages More uniform potency than others Myxedema Treatment or prevention of various types of euthyroid goiters Diagnostic measure to differentiate suspected hyperthyroidism from euthyroidism Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Adverse Reactions of Thyroid Hormones Initial therapy: hyperthyroidism Adverse reactions other than symptoms of hyperthyroidism are rare. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Contraindications, Precautions, and Interactions of Thyroid Hormones Contraindications: Known hypersensitivity After a recent MI Patients with thyrotoxicosis Precautions: Addison disease Lactation Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Contraindications, Precautions, and Interactions of Thyroid Hormones Interactions: Cholestyramine or colestipol Oral anticoagulants Digoxin Diabetes Cardiovascular disease Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Patient Management Issues with Thyroid Hormones • Before therapy, obtain vital signs, weight, and history along with a physical assessment • Administered once per day in the early morning, preferably before breakfast • Levothyroxine – can be given IV or IM • Dose is individualized for the patient • Reassure patient about therapy Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Actions of Antithyroid Drugs Inhibit the manufacture of thyroid hormones Do not affect existing thyroid hormones that are circulating in the blood or stored in the thyroid gland May take 3–4 weeks for therapeutic effects Strong iodide solutions act by decreasing the vascularity of the thyroid gland by rapidly inhibiting the release of the thyroid hormones. Radioactive iodine accumulates in the cells of the thyroid gland where it destroys thyroid cells without damaging other cells throughout the body. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Uses of Antithyroid Drugs • Methimazole and propylthiouracil: used for the medical management of hyperthyroidism • Thyroidectomy may be necessary – May be administered before surgery to temporarily return a patient to a euthyroid state • Strong iodine solution (Lugol solution) – prepares the patient for thyroid surgery • Iodine solutions are used for rapid treatment of hyperthyroidism • Radioactive iodine is used for treatment of hyperthyroidism and selected cases of cancer of the thyroid Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Adverse Reactions of Antithyroid Drugs Methimazole Agranulocytosis Other major reactions: granulocytopenia, thrombocytopenia, aplastic anemia, hypoprothrombinemia, hepatitis Other minor reactions: nausea, vomiting, epigastric distress, paresthesias Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Adverse Reactions of Antithyroid Drugs Propylthiouracil Major adverse reactions are not as common as the minor adverse reactions Major: erythema nodosum, exfoliative dermatitis, aplastic anemia, hypoprothrombinemia, bleeding, hepatitis Minor, but more common: drowsiness, headache, hair loss, epigastric distress Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Adverse Reactions of Antithyroid Drugs Strong iodine solutions Symptoms of iodism: metallic taste in the mouth, swelling and soreness of the parotid glands, burning of the mouth and throat, sore teeth and gums, symptoms of a head cold, occasionally GI upset Allergy to iodine may occur and may be serious Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Adverse Reactions of Antithyroid Drugs Radioactive iodine Sore throat Swelling in the neck Nausea Vomiting Cough Pain on swallowing Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Contraindications, Precautions, and Interactions of Antithyroid Drugs Contraindications Known hypersensitivity Methimazole and PTU: lactation Radioactive iodine: pregnancy and lactation Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Contraindications, Precautions, and Interactions of Antithyroid Drugs Precautions: Methimazole and PTU: pregnancy, patients over 40, patients with a decrease in bone marrow reserve Interactions: Methimazole and PTU: bone marrow depressants (antineoplastic drugs or radiation therapy) PTU: lithium potassium iodide, sodium iodide Iodine products: lithium Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Patient Management Issues with Antithyroid Drugs • Before therapy, patient is assessed for history of the symptoms of hyperthyroidism, vital signs, and weight. • Patient’s allergy history to iodine or seafood is checked. • Patient is monitored for adverse drug effects during treatment. • Patients with an enlarged thyroid may have difficulty swallowing a tablet, so liquid may need to be used. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Patient Management Issues with Antithyroid Drugs Strong iodine solution: Measured in drops and added to water or juice Has a strong, salty taste Patient may need to experiment to determine which fruit juice best disguises the taste Should drink through a straw Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Patient Management Issues with Antithyroid Drugs Radioactive iodine: Oral Single dose Effects are evident within 24 hours Once patient is euthyroid, a thyroid hormone may be added. Patients with hyperthyroidism are likely to have cardiac symptoms that may need to be treated. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Educating the Patient and Family About Antithyroid Drugs Methimazole and propylthiouracil Take at regular intervals around the clock Do not take in larger doses or more frequently Notify health care provider if experience sore throat, fever, cough, easy bleeding or bruising, headache, general feeling of malaise Record weight twice per week Notify health care provider if sudden gain or loss Avoid OTCs Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Educating the Patient and Family About Antithyroid Drugs Strong iodine solution Dilute with water or fruit juice Experiment with juices to determine best juice to mask taste Drink through a straw Discontinue and notify health care provider if experience skin rash, metallic taste in the mouth, swelling and soreness in front of the ear, sore teeth or gums, severe GI distress, or symptoms of a head cold Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins Educating the Patient and Family About Antithyroid Drugs Radioactive iodine Follow the direction of the department of nuclear medicine. Thyroid hormone replacement therapy may be necessary. Follow-up evaluations of the thyroid gland and the effectiveness of treatment are necessary. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins ...
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