1. Pharmacology in Nursing Thyroid and Antithyroid Drugs

2. Thyroid Gland
Secretes three hormones essential for proper regulation of metabolism
Thyroxine (T4)
Triiodothyronine (T3)
Calcitonin
Located near the parathyroid gland
Which is responsible for maintaining adequate levels of calcium in the extracellular fluid

3. Thyroid Gland

4. Hypothyroidism: Deficiency in Thyroid Hormones
Primary: abnormality in the thyroid gland itself
Secondary: results when the pituitary gland is dysfunctional and does not secrete TSH
Tertiary: results when the hypothalamus gland does not secrete TRH, which stimulates the release of TSH

6. Hypothyroidism
Cretinism
Hyposecretion of thyroid hormone during youth
Leads to cretinism: low metabolic rate, retarded growth and sexual development, possibly mental retardation

8. Hypothyroidism (cont’d)
Myxedema
Hyposecretion of thyroid hormone during adulthood
Decreased metabolic rate, loss of mental and physical stamina, weight gain, loss of hair, firm edema, yellow dullness of the skin

10. Hypothyroidism (cont’d)
Goiter
Enlargement of the thyroid gland
Results from overstimulation by elevated levels of TSH
TSH is elevated because there is little or no thyroid hormone in circulation

12. Hypothyroidism (cont’d)
Common symptoms
Thickened skin
Hair loss
Constipation
Lethargy
Anorexia

14. Hyperthyroidism: Excessive Thyroid Hormones
Caused by several diseases
Graves’ disease
Plummer’s disease (toxic nodular disease)
Multinodular disease
Thyroid storm (induced by stress or infection)

17. Hyperthyroidism
Affects multiple body systems, resulting in an overall increase in metabolism
Diarrhea
Flushing
Increased appetite
Muscle weakness
Sleep disorders
Altered menstrual flow
Fatigue
Palpitations
Nervousness
Heat intolerance
Irritability

19. Thyroid Preparations levothyroxine (Synthroid, Levothyroidl)
Synthetic thyroid hormone T4
liothyronine (Cytomel)
Synthetic thyroid hormone T3
liotrix (Thyrolar)
Synthetic thyroid hormone T3-T4 combined
Thyroid
Desiccated (dried) animal thyroid gland

20. Thyroid drugs work the same way as thyroid hormones
Mechanism of Action
Thyroid preparations are given to replace what the thyroid gland cannot produce to achieve normal thyroid levels (euthyroid)
Thyroid drugs work the same way as thyroid hormones

21. To treat all three forms of hypothyroidism
Indications
To treat all three forms of hypothyroidism
Levothyroxine is the preferred drug because its hormonal content is standardized; therefore, its effect is predictable

23. Indications (cont’d)
Also used for thyroid replacement in patients whose thyroid glands have been surgically removed or destroyed by radioactive iodine in the treatment of thyroid cancer or hyperthyroidism

24. Adverse Effects
Cardiac dysrhythmia is the most significant adverse effect
May also cause:
Tachycardia, palpitations, angina, hypertension, insomnia, tremors, headache, anxiety, nausea, diarrhea, menstrual irregularities, weight loss, appetite changes, sweating, heat intolerance, others

25. Treatment of Hyperthyroidism
Radioactive iodine (I131) works by destroying the thyroid gland
Surgery to remove all or part of the thyroid gland
Lifelong thyroid hormone replacement will be needed

26. Treatment of Hyperthyroidism (cont’d)
Antithyroid drugs: thioamide derivatives
methimazole (Tapazole)
propylthiouracil (PTU)

27. Antithyroid Drugs
Used to palliate hyperthyroidism and to prevent the surge in thyroid hormones that occurs after the surgical treatment or during radioactive iodine treatment for hyperthyroidism
May cause liver and bone marrow toxicity

28. Nursing Implications
Assess for drug allergies, contraindications, potential drug interactions
Obtain baseline vital signs, weight
Cautious use advised for those with cardiac disease, hypertension, and pregnant women

29. Nursing Implications (cont’d)
During pregnancy, treatment for hypothyroidism should continue
Fetal growth may be retarded if maternal hypothyroidism is untreated during pregnancy
Adjust dosage every 4 weeks to keep TSH at the lower end of the normal range

30. Nursing Implications (cont’d)
Teach patient to take thyroid drugs once daily in the morning to decrease the likelihood of insomnia if taken later in the day
Teach patient to take the medications at the same time every day and not to switch brands without physician approval

31. Nursing Implications (cont’d)
Teach patients to report any unusual symptoms, chest pain, or heart palpitations
Teach patients not to take OTC medications without physician approval
Teach patients that therapeutic effects may take several months to occur

32. Nursing Implications (cont’d)
Antithyroid medications
Better tolerated when given with food
Give at the same time each day to maintain consistent blood levels
Never stop these medications abruptly
Avoid eating foods high in iodine (seafood, soy sauce, tofu, and iodized salt)

34. Nursing Implications (cont’d)
Monitor for therapeutic response
Monitor for adverse effects