Drugs Affecting the Endocrine System PDF

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Drugs Affecting the Endocrine System  Thyroid and Antithyroid Drugs Thyroid gland is responsible for the secretion of thyroid hormone which is essential for proper regulation of metabolism, cause the homeostatic  Thyroxine (T4)-will become t3, long half-life of 7 days  Triiodothyronine (T3)-active form

Hypothalamus-pituitary Thyroid Axis  Hypothalamus  Thyrotropin-releasing hormone (TRH)-monitors amount of thyroid hormone, a chemical messenger to pituitary  Anterior pituitary  Secretes Thyroid stimulating hormone (TSH) TSH = an email  Thyroid gland: makes thyroid hormone Both  Thyroxine (T4)  Triiodothyronine (T3) T3 and T4:  Both are produced in the thyroid gland through the iodination and coupling of the amino acid tyrosine.  Body needs about 1 mg of iodine per week from the diet. Iodine is absorbed through diet, goes thru thyroid gland, attaches to amino acid tyrosine, outcomes thyroid hormones (babies) T3 and T4 Iodine deficiency: lack of salt: thyroid gland -go bigger and bigger Ex. goiter Autoimmune hypothyroid disease-grave’s disease -protrusion of eyeballs Hypothyroidism:  A condition characterized by diminished production of thyroid hormone.  Primary hypothyroidism stems from an abnormality in the gland itself; gland not producing what it should  Secondary hypothyroidism begins at the level of the pituitary gland and results from reduced levels of TSH (thyroid stimulating hormone).  Third type is caused by reduction in the amount of TRH of thyrotropin releasing hormone by the hypothalamus.  Laboratory values

 Elevated TSH level  Thyroid stimulating hormone (TSH) will be increased because it is working hard to stimulate the production of T3 and T4  Low T3 and T4 levels Hypothyroid TSH high T3 low T4 low Clinical manifestations:  Cold intolerance-always cold  Weight gain  Bradycardia  Lethargy (mental and physical)-slow  Constipation-too much water is absorbed  Firm edema  Hair loss: more common in Females > males  Emergency – Myxedema pt can go into a Coma Myxedema-when thyroid gland becomes life-threatening low (hypothyroid)

Thyroid Hormone  Mechanism of action:  Synthetic form of T4; mimics T4. Works the same way as endogenous thyroid hormone.  Indications:  Given to replace what the thyroid gland cannot produce to achieve normal thyroid levels (euthyroid). Also given to patients whose thyroid glands have been removed surgically or destroyed by radioactive iodine for the treatment of hyperthyroidism or thyroid cancer.  Example:  levothyroxine (Synthroid-brand, Levothroid, Levoxyl)  Interactions:

 Levothyroxine can increase the anticoagulant effects of warfarin (Coumadin): makes you more prone to bleed  Adverse effects:  Overmedication can result in clinical manifestations of hyperthyroidism such as anxiety, tachycardia, palpitations, insomnia Nursing implications:  Obtain baseline vital signs & weight  Monitor and report signs of cardiac excitability (angina, palpitations, dysrhythmia)  Monitor client’s TSH and T4 levels  During pregnancy treatment for hypothyroidism should continue; must continue taking her medication if pregnant -Cretinism  Cretinism is a condition of severely stunted physical and mental growth usually due to untreated maternal hypothyroidism. Not common anymore due to T4 synthetic thyroid hormone Patient Education:  Instruct client to take daily on an empty stomach before breakfast  Take in the morning to decrease the likelihood of insomnia at night  Full therapeutic effects may take several weeks to occur  Report any unusual symptoms (e.g. chest pain or heart palpitations)  Therapy is lifelong  Increased HR, palpitations, and feelings of anxiety are normal Should write down patient education, ensure a second pair of ears if possible Do not take with grapefruit juice: with increase toxicity the drug Clinical Pearl  Levothyroxine is the preferred drug because its hormonal content is standardized (100% T4); therefore, its effect is predictable. Concerns regarding the interchangeability of brands have been raised. Patients must be instructed to check with their provider before switching to another brand as close monitoring and dosage adjustments may be necessary. Hospital formulary: a hospital may only carry a certain brand Pt must request levothyroxine if hospital does not carry it/have it on their formulary.

Hyperthyroidism:  Excessive secretion of thyroid hormones caused by:  Graves’ disease  Toxic nodular disease Body is sped up Overstimulate thyroid gland Clinical Manifestations of Hyperthyroidism  Heat intolerance-too hot, oversweating  Tachycardia  Heart palpitations  Anxiety  Tremor-shakes  Insomnia  Diarrhea  Flushing  Increased appetite  Weight loss  Muscle weakness  Fatigue  Emergency – thyroid storm Hyper TSH low T3 high T4 high Body is telling thyroid stop producing thyroid hormones! body has way too much  Exophthalmos as a result of Graves’ hyperthyroidism White is visible above the iris  Laboratory values  Decreased TSH level  Thyroid stimulating hormone (TSH) will be decreased in an attempt by the body to decrease the production of T3 and T4  Elevated T3 and T4 levels Treatment:  Antithyroid drugs  methimazole (Tapazole)

 propylthiouracil (PTU)  Radioactive iodine (I131) works by destroying the thyroid gland-PO, kills thyroid cells  Surgery to remove all or part of the thyroid gland  Lifelong thyroid hormone replacement may become necessary Pt is put on a beta blocker immediately, to slow HR Mechanism of Action:  Mechanism of action/ drug effects:  Inhibits the incorporation of iodine molecules into the amino acid tyrosine. This prevents the formation of the thyroid hormone (T3 and T4). Neither drug can inactivate already existing thyroid hormone. =not coupled=decreased Does not affect existing thyroid hormone Has a long half-life of 7 days, body must rid of existing thyroid hormones, this drug only inhibits new ones from forming  Adverse effects:  Overmedication as indicated by S/S of hypothyroidism  Agranulocytosis (↓WBC)  Hepatitis (↑LFT) Clinical Reasoning  S.R. has just done a home pregnancy test and is elated to see that she is pregnant. She wants to stop taking her levothyroxine because she wants this pregnancy to be “natural.” What advice should she receive? She is hypo, no she cannot stop, the baby needs this  J.B. has been taking levothyroxine for the first time, and at her two-week follow-up appointment, she tells the nurse, “I just can’t sleep at night! I feel so nervous.” Her thyroid levels are all within normal ranges. What could be the problem? She has hyperthyroidism, she should take it this morning, not at night to prevent insomnia.  A patient asks the nurse why she is taking propranolol (Inderal) along with her therapy for hyperthyroidism. Explain the rationale for this. The hyperthyroidism increases her HR, so taking this beta blocker will slow her heart rate  D.S. has been taking antithyroid medication but went on vacation and forgot to bring her medication. She begins to feel weak, with an irregular,

rapid heartbeat, flushed skin, and confusion. She is taken to the hospital for treatment of what possible problem? -thyroid storm – EMERGENCY __ 1. Cretinism ___ 2. Increased appetite ___ 3. Loss of physical stamina ___ 4. Weight gain ___ 5. Weight loss __ 6. Palpitations ___ 7. Heat intolerance ___ 8. Cold intolerance ___ 9. Myxedema ___ 10. Loss of hair Answers 1. Hypo 2. Hyper 3. Hypo 4. Hypo 5. Hyper 6. Hyper 7. Hyper 8. Hypo 9. Hypo 10. Hypo

Corticosteroids (Glucocorticoids)  Adrenal gland has two parts:  Adrenal cortex-outer  Adrenal medulla-inner  Each part has different functions and secretes different hormones  Adrenal medulla secretes catecholamines (mimic sympathetic system)  Epinephrine

 Norepinephrine  Adrenal cortex secretes corticosteriods  Glucocorticoids (primarily cortisol)-necessary for life, balance glucose levels, makes cortisol on demand, cannot store it  Mineralocorticoids (primarily aldosterone)  Androgens  Gluccocorticoid (Cortisol)  Regulated by hypothalmus / pituitary gland  Very little adrenal storage  Mineralcorticoid (Aldosterone)  Regulated by RAAS  Hypothalamus  Corticotropin-releasing hormone (CRH): sends message to ACTH  Anterior pituitary  Adrenocorticotropic hormone (ACTH): messenger to adrenal gland asking for cortisol  Adrenal gland  Cortisol  Cortisol can help control blood sugar levels, regulate metabolism, help reduce inflammation, and assist with memory formulation.

Glucocorticoid: best anti-inflammatory medicine, powerful immune suppressant, IV or PO Glucocorticoids:  Mechanism of action:  Pharmacologic dose (much higher than the level produced by the body) causes inhibition of inflammatory and immune responses. Also, promotes the breakdown of glycogen in the liver and the redistribution of fat from peripheral to central areas of the body.

Way safer by lowering dosage Must taper systemic steroid  Indications:  Severe inflammation and immune responses  Examples:  Hydrocortisone (synthetic cortisol, medical dosage is much higher) If pt is on this drug the side effects include: Will cause fat redistribution ex. Moon face, skinny arms and legs, “baseball hump” , higher Bp, lower glucose levels Moon face: High-dose corticosteroid therapy produces a characteristic “moon face” appearance. Cushingoid Appearance:

 Use to treat a number of different disorders especially inflammatory or immunologic disorders : goal: to suppress immune system  Allergic reactions  Asthma

 Rheumatoid arthritis  Dermatitis  Systemic lupus erythematosus  Inflammatory bowel disorders (Ulcerative Colitis or Crohn’s)  Organ transplant (decrease immune response to prevent organ rejection) Forms:  Glucocorticoid administration  By inhalation for control of steroid-responsive bronchospastic states (fluticasone, Advair)  Nasally for rhinitis (fluticasone, Flonase)-inflammation of nose  Topically for inflammations of the eye, ear, and skin (hydrocortisone)  Orally tablet or liquid form (prednisone, dexamethasone)  Intravenously (IV) (methyl prednisone or Solu-medrol) Whenever possible, use topical, use systemic for shortest duration possible, due to high risk of side effects Clinical pearl:  Whenever possible the physician / nurse practitioner will prescribe a topical, nasal spray, eye drops or inhaled dosage before going to an oral route or intravenous route.  Oral and intravenous routes are usually higher dosages and more likely to have side effects. Adverse effects:  CNS  Nervousness, insomnia, “steroid psychosis”  Cardiovascular  HTN  High blood pressure  Endocrine  Growth suppression, Cushing’s syndrome, menstrual irregularities, hyperglycemia

 GI 

  

 Peptic ulcers with possible perforation Integumentary  Fragile skin, ecchymosis, facial erythema, poor wound healing, hirsutism Musculoskeletal  Muscle weakness, loss of muscle mass, osteoporosis Ocular  Increased intraocular pressure, glaucoma Other  Weight gain

Contraindications/Precautions:  Contraindications:  Serious infections including septicemia, systemic fungal infections, and varicella  Precautions:  Gastritis, ulcer disease  Diabetes  Heart, liver, renal disease Nursing Implications:  Assess for contraindications to adrenal drugs, especially the presence of peptic ulcer disease  Be aware that these drugs may alter serum glucose levels-monitor glucose levels  Oral forms should be given with food or milk to minimize GI upset  Clear nasal passages before giving a nasal corticosteroid: blow your nose before giving medical nasal spray  After using an orally inhaled corticosteroid, instruct patients to rinse their mouths to prevent possible oral fungal infections ex. Jacob with asthma

 Teach patients on corticosteroids to avoid contact with people with infections and to report any fever, increased weakness, lethargy, or sore throat Steroid is always spit out Nystatin-anti fungal mouthwash that they swallow  Patients should be taught to take all adrenal medications at the same time every day, usually in the morning, with meals or food Ex. Oral candiasis-white excess on tongue cannot be scraped off, will bleed if attempted  Patients should not take with alcohol, aspirin, or NSAIDs  Sudden discontinuation of these drugs can precipitate an adrenal crisis  Doses are usually tapered before the drug is discontinued Practice  Define taper…  Why must corticosteroids be tapered? Must be tapered , less and less dose, dose is frequently decreased i.e. 40 mg, 30 mg, 20 mg, 10 mg  A patient who has been taking daily prednisone for 6 months to prevent rejection of his heart transplant has contracted the stomach flu and has been unable to keep anything in his stomach for 2 days due to vomiting. Are there any concerns about this and his ability to take the prednisone? -cant get anything down, needs IV form...