By the end of this section, you should be able to:<\/p>\n\n\n\n
Thyroid drugs<\/strong> are used when the thyroid is functioning incorrectly and there is a need to replace the thyroid hormone so that the body can maintain its expected function. Thyroid drugs can be synthetic thyroid hormones or animal-based thyroid hormones. These drugs act by replacing the body\u2019s natural thyroid hormone when the levels are low or absent within the body.<\/p>\n\n\n\n Levothyroxine sodium is a synthetic thyroid hormone that is identical to T4 produced in the body. The gastrointestinal tract absorbs 40%\u201380% of this synthetic hormone. The drug is greater than 99% protein bound and easily distributed. It is primarily eliminated by the kidneys, with approximately 20% of T4 being excreted in the stool (Eghtedari & Correa, 2022). It comes in tablet and injectable forms and is used to treat hypothyroidism and pituitary TSH suppression. Levothyroxine is contraindicated in clients with uncorrected adrenal insufficiency: because of the role of adrenal glands in regulating stress response and cortisol production, levothyroxine\u2019s ability to increase metabolic demands and stress may overwhelm the impaired adrenal glands, causing an adrenal crisis. Stabilization of adrenal function is crucial before starting levothyroxine treatment to prevent an adrenal crisis.<\/p>\n\n\n\n Levothyroxine sodium has a narrow therapeutic index; careful dose titration is necessary to avoid overtreatment or undertreatment. Clients should take this drug in the morning at least 30 minutes before consuming food or fluid containing caffeine such as coffee, tea, or soda. Food and caffeinated drinks can both interfere with the absorption of levothyroxine sodium.<\/p>\n\n\n\n Liothyronine sodium is a synthetic thyroid hormone mimicking T3. This hormone replacement is commonly used to treat hypothyroidism and myxedema coma. Liothyronine can be taken orally, comes in an intravenous form, and is easily absorbed and readily distributed in the body. As with levothyroxine, liothyronine is contraindicated in clients with uncorrected adrenal insufficiency. As stated above, the adrenal glands control the stress response and cortisol levels within the body. When they are impaired, they are unable to handle the increase in metabolic rate caused by the administration of liothyronine, leading to an adrenal crisis. Adverse effects of liothyronine include anxiety, blurred vision, chest discomfort, decreased bone mineral density, and decreased urine output.<\/p>\n\n\n\n Do not confuse levothyroxine<\/em> sodium with liothyronine<\/em> sodium. Although these drugs are in the same drug class, they require different dosing and lab monitoring.<\/p>\n\n\n\n Desiccated thyroid extract\u00a0is a thyroid hormone developed from pig glands that is often used as an over-the-counter remedy for thyroid hormone replacement. Desiccated thyroid extract has not been approved by the Food and Drug Administration (FDA) due to a complex manufacturing process leading to issues with safety, effectiveness, and quality, with inconsistent or inaccurate dosage.\u00a0Table 27.2\u00a0lists common thyroid drugs and typical routes and dosing for adult clients.<\/p>\n\n\n\n Table<\/strong> 27.2<\/strong> Drug Emphasis Table: Thyroid Drugs<\/strong> (source: https:\/\/dailymed.nlm.nih.gov\/dailymed\/)<\/p>\n\n\n\n Common adverse effects among the thyroid drug classification include cardiac effects\u2014such as tachycardia, palpitations, and arrhythmias\u2014weight loss, nervousness and irritability, heat intolerance, diarrhea, abdominal cramping, headaches, and sleep disturbances.<\/p>\n\n\n\n Contraindications for thyroid drug classification include hypersensitivity to the drug or any of its components as well as any recent myocardial infarction because thyroid drugs can increase heart rate and heart contractility. Untreated adrenal insufficiency is a contraindication because impaired adrenal glands cannot handle the increased metabolic rate cause by thyroid drugs, as is hyperthyroidism since the drugs would increase thyroid hormone levels that are already elevated.<\/p>\n\n\n\n Table 27.3\u00a0is a drug prototype table for thyroid drugs featuring levothyroxine sodium. It lists drug class, mechanism of action, adult dosage, indications, therapeutic effects, drug and food interactions, adverse effects, and contraindications.<\/p>\n\n\n\n Table<\/strong> 27.3<\/strong> Drug Prototype Table: Levothyroxine Sodium<\/strong> (source: https:\/\/dailymed.nlm.nih.gov\/dailymed\/)<\/p>\n\n\n\n The nurse should do the following for clients who are taking thyroid drugs:<\/p>\n\n\n\n The client taking a thyroid drug should:<\/strong><\/p>\n\n\n\n The client taking a thyroid drug should not<\/em>:<\/strong><\/p>\n\n\n\n Thyroid Hormones<\/strong><\/p>\n\n\n\n Thyroid hormones, including levothyroxine sodium, either alone or with other therapeutic agents, should not be used for treatment of obesity or weight loss due to producing serious toxicity or life-threatening manifestations.<\/p>\n\n\n\n Antithyroid drugs<\/strong> are used to inhibit production of the thyroid hormone so that the body can maintain normal thyroid homeostasis. Antithyroid drugs act by inhibiting the synthesis of thyroid hormones or by inundating the thyroid gland with iodine to prevent thyroid hormone release. Antithyroid drugs are used when the thyroid hormone levels are elevated within the body.<\/p>\n\n\n\n Thionamides are compounds that effectively hinder the synthesis of thyroid hormones. These compounds are transported into the thyroid gland and act by inhibiting two critical processes: organification<\/strong> of iodine to tyrosine residues in thyroglobulin<\/strong> as well as coupling of iodotyrosines<\/strong>, leading to lower serum levels of thyroid hormones. The process of organification of iodine to tyrosine residues refers to the incorporation of iodine atoms into tyrosine amino acid molecules within the structure of thyroglobulin, a protein produced by the thyroid gland. This is an essential step in the synthesis of thyroid hormones. The coupling of iodotyrosines refers to the binding together of iodinated tyrosine molecules within the thyroglobulin to form the final thyroid hormones T3 and T4. Thionamides are used in the treatment of hyperthyroidism and Graves\u2019 disease. Thionamides include methimazole and propylthiouracil.<\/p>\n\n\n\n Methimazole inhibits the synthesis of thyroid hormones and is indicated to treat hyperthyroidism. This medication is rapidly absorbed in the gastrointestinal tract and metabolized rapidly. It is excreted mainly in the urine but is excreted in breast milk and should be used cautiously with clients who are breastfeeding. Careful dose titration is necessary to avoid overtreatment or undertreatment. When the client develops toxicity to methimazole, symptoms such as nausea, vomiting, epigastric distress, headache, fever, joint pain, pruritus, edema, and agranulocytosis may develop (Armstrong et al., 2022; DailyMed, Methimazole,<\/em> 2022; Shahid et al., 2022; Singh & Correa, 2022).<\/p>\n\n\n\n Propylthiouracil inhibits the synthesis of thyroid hormones. This drug is readily absorbed and extensively metabolized; it is mainly excreted in the urine. Propylthiouracil is indicated for Graves\u2019 disease with hyperthyroidism, multinodular goiter<\/strong>, and to ameliorate symptoms of hyperthyroidism before thyroidectomy or radioactive iodine therapy in clients who did not tolerate methimazole. It is contraindicated in clients with hypersensitivity and with liver failure. Adverse effects include hepatitis, jaundice, anemia, thrombocytopenia, nephritis, arthralgia, and paresthesia.<\/p>\n\n\n\n The body naturally uses iodine<\/strong> for the formation of thyroid hormone. Iodine solutions cause the thyroid cells to become inundated with iodine, thereby decreasing thyroid hormone production. Iodine preparations are used to treat hyperthyroidism when thionamides are ineffective or for those clients who are not candidates for surgery.<\/p>\n\n\n\n Potassium iodide prevents iodine from getting into the thyroid gland. As a medication, potassium iodine is used two separate ways: 1) to treat hyperthyroidism by inhibiting thyroid hormone secretion in very acute situations, and 2) to prevent the uptake of radioactive iodine in the event of a nuclear emergency. Additional use includes radioactive iodine to ablate a hyperactive thyroid gland. Adverse effects include skin rash, shortness of breath, wheezing, swelling, fever, and joint pain. It is contraindicated in those who have had an allergic reaction to iodine and those with nodular thyroid disease. ThyroShield and Thyrosafe are the only FDA-approved brands of potassium iodide.<\/p>\n\n\n\n Table 27.4\u00a0lists common antithyroid drugs and typical routes and dosing for adult clients.<\/p>\n\n\n\n Table<\/strong> 27.4<\/strong> Drug Emphasis Table: Antithyroid Drugs<\/strong> (source: https:\/\/dailymed.nlm.nih.gov\/dailymed\/)<\/p>\n\n\n\n Common adverse effects include:<\/p>\n\n\n\n Contraindications include hypersensitivity to the drug or any of its components, severe liver disease or impairment, and with pregnancy or breastfeeding because the drugs can cross the placenta, be excreted in breast milk, and potentially affect the development of the fetus or infant.<\/p>\n\n\n\n Table 27.5\u00a0is a drug prototype table for antithyroid drugs featuring methimazole. It lists drug class, mechanism of action, adult dosage, indications, therapeutic effects, drug and food interactions, adverse effects, and contraindications.<\/p>\n\n\n\n Table<\/strong> 27.5<\/strong> Drug Prototype Table: Methimazole<\/strong> (source: https:\/\/dailymed.nlm.nih.gov\/dailymed\/)<\/p>\n\n\n\n The nurse should do the following for clients who are taking antithyroid drugs:<\/p>\n\n\n\n The client taking an antithyroid drug should:<\/strong><\/p>\n\n\n\n The client taking an antithyroid drug should not:<\/em><\/strong><\/p>\n\n\n\n Propylthiouracil<\/strong><\/p>\n\n\n\n Severe liver injury and acute liver failure have been reported in clients treated with propylthiouracil.<\/p>\n\n\n\n Read the following clinical scenario to answer the questions that follow.<\/p>\n\n\n\n Ellis Dominico is a 40-year-old client who visits their primary health care provider\u2019s office for a checkup. Ellis reports fatigue and decreased energy, constipation, and having an intolerance to cold temperatures. Table<\/strong> 27.6<\/strong><\/p>\n\n\n\nLevothyroxine Sodium<\/h3>\n\n\n\n
Liothyronine Sodium<\/h3>\n\n\n\n
Safety Alert<\/h2>\n\n\n\n
Similarly Named Drugs<\/h3>\n\n\n\n
Desiccated Thyroid Extract<\/h3>\n\n\n\n
Drug<\/strong><\/th> Routes and Dosage Ranges<\/strong><\/th><\/tr><\/thead> Levothyroxine sodium (Synthroid, Levoxyl)<\/td> Individualized dosing due to a narrow therapeutic index.
Standard dosing starts at 1.6 mcg\/kg\/day orally; increase by 12.5\u201325 mcg orally every 4\u20136 weeks if needed.
Serum T4 levels should be used to monitor therapeutic dosing range of drug.
Must be titrated based on the individual\u2019s need and to avoid the consequences of overtreatment or undertreatment.<\/td><\/tr>Liothyronine sodium
(Cytomel, Triostat)<\/td>25 mcg orally once daily; increase by 25 mcg orally daily every 1\u20132 weeks if needed.
Maintenance dose: 25\u201375 mcg once daily.
Serum T3 levels should be used to monitor therapeutic dosing range of drug.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\nAdverse Effects and Contraindications<\/h3>\n\n\n\n
Drug Class<\/strong>
Thyroid hormone
Mechanism of Action<\/strong>
Replaces the amount of hormone the thyroid is unable to produce, helping to restore thyroid hormone homeostasis within the body<\/td>Drug Dosage<\/strong>
Individualized dosing due to a narrow therapeutic index.
Standard dosing starts at 1.6 mcg\/kg\/day orally; increase by 12.5\u201325 mcg orally every 4\u20136 weeks if needed.
Serum T4 levels should be used to monitor therapeutic dosing range of drug.
Must be titrated based on the individual\u2019s need and to avoid the consequences of overtreatment or undertreatment.<\/td><\/tr>Indications<\/strong>
Hypothyroidism
Pituitary TSH suppression
Therapeutic Effects<\/strong>
Restores thyroid hormone levels to normal
Maintains thyroid hormone homeostasis<\/td>Drug Interactions<\/strong>
Dopamine
Glucocorticoids
Octreotide
Amiodarone
Digitalis
Iodine
Lithium
Calcium
Iron
Warfarin
Food Interactions<\/strong>
Soy
Soybean flour
Cotton seed meal
Walnuts
Dietary fiber may bind to levothyroxine sodium and decrease its absorption<\/td><\/tr>Adverse Effects<\/strong>
Irregular heartbeat
Heat intolerance
Irregular breathing
Irritability
Nausea
Tremors
Decreased urine output<\/td>Contraindications<\/strong>
Adrenal insufficiency
Nontoxic goiter or nodular thyroid disease
Caution:
Monitor closely when administering to older clients who have underlying cardiovascular disease\u2014may precipitate thyrotoxicosis<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\nNursing Implications<\/h3>\n\n\n\n
\n
Client Teaching Guidelines<\/h2>\n\n\n\n
\n
\n
FDA Black Box Warning<\/h2>\n\n\n\n
Antithyroid Drugs<\/h2>\n\n\n\n
Thionamides<\/h3>\n\n\n\n
Methimazole<\/h4>\n\n\n\n
Propylthiouracil<\/h4>\n\n\n\n
Iodine<\/h3>\n\n\n\n
Potassium Iodide<\/h4>\n\n\n\n
Drug<\/strong><\/th> Routes and Dosage Ranges<\/strong><\/th><\/tr><\/thead> Methimazole
(Tapazole)<\/td>Mild hyperthyroidism:<\/em> 15 mg orally daily.
Moderate hyperthyroidism:<\/em> 30\u201340 mg orally daily.
Severe hyperthyroidism:<\/em> 60 mg orally daily, divided into 3 doses at 8-hour intervals.
Maintenance dose:<\/em> 5\u201315 mg orally daily.<\/td><\/tr>Propylthiouracil
(PTU)<\/td>300\u2013400 mg orally daily; maintenance dose 100\u2013150 mg orally daily.<\/td><\/tr> Potassium iodide (Thyrosafe)<\/td> 130 mg orally daily at 24-hour intervals.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n Adverse Effects and Contraindications<\/h3>\n\n\n\n
\n
Drug Class<\/strong>
Antithyroid agent
Mechanism of Action<\/strong>
Inhibits the synthesis of thyroid hormones and thus is effective in the treatment of hyperthyroidism<\/td>Drug Dosage<\/strong>
Mild hyperthyroidism:<\/em> 15 mg orally daily.
Moderate hyperthyroidism:<\/em> 30\u201340 mg orally daily.
Severe hyperthyroidism:<\/em> 60 mg orally daily, divided into 3 doses at 8-hour intervals.
Maintenance dose:<\/em> 5\u201315 mg orally daily.<\/td><\/tr>Indications<\/strong>
Hyperthyroidism
Ameliorating hyperthyroidism in preparation for subtotal thyroidectomy or radioactive iodine therapy
When thyroidectomy is contraindicated or not advisable
Therapeutic Effects<\/strong>
Lowers thyroid hormone levels
Relieves\/reduces manifestations of hyperthyroidism<\/td>Drug Interactions<\/strong>
Anticoagulants
Beta-adrenergic blockers
Digitalis glycosides
Theophylline
Food Interactions<\/strong>
No significant interactions<\/td><\/tr>Adverse Effects<\/strong>
Agranulocytosis
Thrombocytopenia
Aplastic anemia
Fever
Insulin autoimmune syndrome (low blood glucose levels)
Jaundice
Urticaria
Epigastric distress
Arthralgia<\/td>Contraindications<\/strong>
Hypersensitivity
Pregnancy and breastfeeding
Caution:
Monitor closely for agranulocytosis and hepatotoxicity<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\nNursing Implications<\/h3>\n\n\n\n
\n
Client Teaching Guidelines<\/h2>\n\n\n\n
\n
\n
FDA Black Box Warning<\/h2>\n\n\n\n
Case Study<\/h2>\n\n\n\n
History<\/strong>
Hyperthyroidism (diagnosed 6 months ago)
Current Medications<\/strong>
Methimazole, 15 mg orally daily<\/p>\n\n\n\nVital Signs<\/strong><\/th> Physical Examination<\/strong><\/th><\/tr><\/thead> Temperature:<\/em><\/td> 98.3\u00b0F<\/td> Head, eyes, ears, nose, throat (HEENT):<\/em> Within normal limitsCardiovascular:<\/em> No jugular vein distention; no peripheral edema noted; S1, S2 auscultated, rhythm regularRespiratory:<\/em> Lungs clear to auscultation bilaterallyGI:<\/em> Abdomen firm, nontender, slightly distendedGU:<\/em> Client reports urinary output unchanged from their baselineNeurological:<\/em> Lethargy and slow speech noted; no other neurological deficits notedIntegumentary:<\/em> No wounds noted; skin appropriate for age<\/td><\/tr> Blood pressure<\/em>:<\/td> 96\/58 mm Hg<\/td><\/tr> Heart rate:<\/em><\/td> 58 beats\/min<\/td><\/tr> Respiratory rate<\/em>:<\/td> 18 breaths\/min<\/td><\/tr> Oxygen saturation<\/em>:<\/td> 95% on room air<\/td><\/tr> Height<\/em>:<\/td> 5’6″<\/td><\/tr> Weight<\/em>:<\/td> 211 lb (10 lb heavier than weight 3 months ago)<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n