Pituitary Agents


The Endocrine System-
  • The main goal of the endocrine system is to maintain the physiologic stability.
  • The endocrine system also communicates through hormones that are secreted into the bloodstream in response to the body's needs and [[#|travel]]through the blood to the site of action or target cell.
Neuroendocrine System and Pituitary Hormones-
  • The Hypothalamus is part of the central nervous system (CNS), and controls the pituitary.
  • The Pituitary gland is made up of two distinct lobes: the anterior and the posterior.
  • Each lobe secretes its own different set of hormones. Both the hypothalamus and the pituitary gland [[#|work]]together to govern all body functions and operate in a stimulus-and-response manner.
  • Negative feedback loop- Hormone secretion is commonly regulated by this mechanism. For example, when gland X releases hormone X, this stimulates target [[#|cells]]to release hormone Y. When there is an [[#|excess]]of hormone Y, gland X senses this [[#|excess]]and decreases its release of hormone X.

Hormones of the Anterior and Posterior Pituitary-
  • Anterior pituitary agents- Corticotropin-ACTH, Follicle stimulating hormone-FSH, Somatrem and somatotropin ([[#|Growth hormone]]), octreotide ([[#|Growth hormone]] antagonist).
  • Posterior pituitary agents- Vasopressin (ADH) and [[#|Desmopressin]]( Anti-diuretic hormone and Clotting Factor).
Pituitary Agents purpose-
  • As [[#|replacement]][[#|therapy]]to make up for hormone deficiency or as diagnostic aids to determine the status of the patient's hormonal functions.
Mechanism of Action-
  • The mechanisms of action of the various pituitary drugs differ depending on the drug, but overall they either augment or antagonize the natural effects of the pituitary hormones.


Pituitary Drugs

Classification
Drug Name
Indication
Mechanism of Action
[[#|Side Effects]]
Pituitary Agent
-Adrenocorticotropic Hormone (ACTH)
Corticotropin
-[[#|Multiple sclerosis]]
-Insufficiency caused by long-term corticosteroid use
-Stimulates release of cortisol from the adrenal cortex
-Used to diagnose, but not treat, adrenocortical insufficiency
-Anti-inflammatory effects
-Renal retention of sodium (Edema, [[#|hypertension]])

-Abnormal distribution of fat
-Delayed wound healing
-Allergic reactions
-Black stools, coughing up blood
-Bruising
-Buzzing in the ears
-Chest pain or tightness
-Confusion/disorientation
Pituitary Agent
-Growth Hormone
Somatrem and Somatotropin
- Stimulate skeletal growth in patients with deficient [[#|Growth Hormone]]
  • Such as hypopituitary dwarfism
- Recombinantly made [[#|growth hormone]](GH)
-Bone pain
-Headache
-Increased sweating
-Mild flu-like symptoms
-Joint Pain
-Redness or itching at the injection site
Pituitary Agent
-Growth Hormone Antagonist
Octreotide
Acromegaly (Gigantism)
Excess growth hormone
Usually the result of pituitary tumor
-Growth hormone antagonist
-Abdominal pain/discomfort
-Diarrhea
-Nausea
-Gallstones
-Pain at injection site
Pituitary Agent
Antidiuretic Hormone
Vasopressin
-Used in the treatment of Diabetes Insipidus
-Mimic actions of Antidiuretic hormone
( Caused by Vasocontriction)
-HTN, MI
-Sweating, alopecia
-Tremor, Vertigo, Headache
Pituitary Agent
Antidiuretic Hormone
Factor VIII Clotting Factor
Desmopressin
-Used in the treatment of Diabetes Insipidus
-Used in clotting disorders
Hemophilia
-Mimic actions of
-Antidiuretic hormone
In addition assists with clotting factor VIII
Same as above

Hypopituitary Dwarfism


What is Acromegaly?

Diabetes Insipidus- A condition in which the kidneys are unable to conserve water.
  • Symptoms include: excessive thirst which may be intense or uncontrollable, may involve cravings for ice water and excessive urine volume

Contraindications
  1. Corticotropin (ACTH)-
  • Hypersensitivity, Scleroderma (Hypertensive Crisis), Osteoporosis (increased excretion of calcium), Heart failure/ HTN (Fluid retention), Peptic Ulcer disease (can cause gastrointestinal perforation) and recent surgery (Immunosuppressive properties).
2. Somatropin and Somatrem (Growth Hormone)-
  • Bones that have stopped growing because if they are not continually growing the drugs will not work.
  • Evidence of an active tumor because the medication could potentially increase it's growth.

3. Vasopressin (ADH)-
  • Chronic nephritis

4. Octreotide (Growth Hormone Antagonist)-
  • Hypersensitivity to it or to similar drugs.

Nursing Implications- Monitor for therapeutic responses.
  1. Corticotropin (ACTH)- has eliminated pain associated with inflammation. Also, it has produced increased comfort and muscle strength in patients with multiple sclerosis.
  2. Somatropin (Growth Hormone- Should increase growth in children.
  3. Desmopressin, Vasopressin (ADH)- Should reduce severe thirst and decrease urinary output. Desmopressin should cause increased clotting ability in patients with Factor VIII insufficiency.

Monitor for side effects-
  1. Agents should not be discontinued abruptly.
  2. Parents of children who are receiving growth hormones should keep a journal reflecting the child's growth.
  3. Patients should be taught to rotate injection sites.


Thyroid and Anti-thyroid Agents


Thyroid hormones:
  • Regulate lipid and carbohydrate metabolism, essential for growth and development
  • Control the heat regulating system of the body
  • Multiple effects on the cardiovascular, endocrine and neuromuscular systems.

Thyroid Gland
  • Secretes three hormones essential for proper regulation of metabolism
  1. Thyroxine (T4)- Metabolic rate
  2. Triiodothyronine (T3)- Secondary to T4
  3. Calcitonin- Located near the parathyroid gland and is responsible for maintaining adequate levels of calcium in the extracellular fluid

Facts: T4 and T3 are produced in the thyroid gland. The iodine needed for this process is acquired from the diet. Iodine is sequestered in the thyroid gland until it is needed. The whole process is triggered by thyroid stimulating hormone TSH which is released from the anterior pituitary gland.

Hypothyroidism: A 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
Common Symptoms:
Thickened skin, hair loss, constipation, lethargy and anorexia.
METABOLISM IS MOVING SLOW!

Cretinism-
  • Hyposecretion of thyroid hormone during youth which leads to cretinism. Cretinism is characterized by low metabolic rate, retarded growth and sexual development and possibly mental retardation.
Myxedema-
  • Hyposecretion of thyroid hormone as an adult. Myxedema is characterized by decreased metabolic rate, loss of mental and physical stamina, weight gain, loss of hair, FIRM EDEMA and yellow dullness of the skin.
Goiter-
  • Enlargement of the thyroid gland. A goiter results from overstimulation by elevated levels of Thyroid Stimulating Hormone (TSH). TSH is elevated because there is little or no thyroid hormone in circulation.

Thyroid Preparations-
  • levothyroxine (Synthroid, Levoxyl)

A synthetic thyroid hormone T4.
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.
Indications: To treat all three forms of hypothyroidism. Thyroid replacement in patients whose thyroid glands have been surgically removed or destroyed by radioactive iodine in the treatment of thyroid cancer or hyperthyroidism. Levothyroxine (Synthroid) is the preferred agent because its hormone content is standardized and the effect is predictable.
Contraindications: If you have a known drug allergy to the medication, recent myocardial infarction (risk of dysrhythmias and hypertension), adrenal insufficiency (acute adrenal crisis) and Hyperthyroidism.
Side Effects: They are caused by increasing your metabolism!

Nursing Implications for Thyroid Replacement Medications
Teach patient:
  1. Take thyroid medications once daily in the morning to decrease the likelihood of insomnia.
  2. Take the medications at the same time each day; don't switch brands without doctors approval.
  3. Report any unusual symptoms, chest pain, or heart palpitations.
  4. Therapeutic effects may take several months to occur.
  5. Too high of a dose of a thyroid agent will result in nervousness, irritability, and insomnia.
  6. Assess for drug allergies, contraindications, potential drug interactions.
  7. Obtain baseline vital signs and weight the patient.
  8. Be cautious in using these medications in those with cardiac disease, hypertension, and pregnancies.


Hyperthyroidism: An excess in thyroid hormones

  • Hyperthyroidism is caused by several diseases including Graves' disease which is the most common.
  • It affects multiple body systems, resulting in an overall increase in metabolism.

Graves Disease Symptoms-
  • Anxiety, Difficulty concentrating, exophthalmos, eye irritation, tearing, frequent bowel movements, heat intolerance, flushing, increased appetite, insomnia, menstrual irregularities, rapid or irregular heartbeat, tremor or goiter

Treatment of Hyperthyroidism-
  • Antithyroid drugs: Thioamide derivatives (Propylthiouracil PTU)
  • Radioactive iodine- works by destroying the thyroid gland
  • Surgery to remove all or part of the thyroid gland

Indications: Used to palliate hyperthyroidism and to prevent the surge in thyroid hormones that occurs after the surgical treatment. Used during radioactive iodine treatment for hyperthyroidism. May cause liver and bone marrow toxicity!
Mechanism of Action: Normalizes the overall metabolic rate by inhibiting the production of thyroid hormone T3 and T4.

Nursing implications for Antithyroid Medications
Teach patient:
  1. They are better tolerated when given with food.
  2. Give at the same time each day to maintain consistent blood levels
  3. Never stop these medications abruptly
  4. Avoid eating foods high in iodine (seafood, soy sauce, tofu, and iodized salt) Iodine needed for synthesis of thryoid hormone.

Thyroid Drugs

Thyroid Agent
Levothyroxine
(Synthroid, Levoxyl)
-To treat all three forms of hypothyroidism
-Thyroid replacement in patients whose thyroid glands have been surgically removed or destroyed
-Synthetic thyroid hormone T4
Cardiovascular
-tachycardia, palpitations, hypertension
Central Nervous System
-insomnia, tremors, headache, anxiety
Gastrointestinal
-nausea, diarrhea, increased or decreased appetite, cramps
Other
- menstrual irregularities, weight loss, sweating, heat intolerance, fever
Antithyroid Agent
Propylthiouracil (PTU)
-hyperthyroidism
-To prevent the surge in thyroid hormones that occurs after the surgical treatment or during radioactive iodine treatment for hyperthyroid
-Normalizes the overall metabolic rate by inhibiting the production of thyroid hormone T3 and T4.
Bone marrow suppression
Drowsiness, headache, vertigo, rash

Monitor for therapeutic responses

  • Thyroid Agents-
  1. Disappearance of symptoms of hypothyroidism such as depression, constipation, loss of appetite, weight gain, cold intolerance, syncope, and dry and brittle hair.
  • Antithyroid Agents-
  1. Disappearance of symptoms of hyperthyroidism such as anxiety, loose stool, increased appetite, heat intolerance, and elevated blood pressure.

QUIZ!

  1. Which pituitary agent is used in the treatment of both Diabetes Insipidus and in clotting disorders?
  2. Hyposecretion of thyroid hormone as a child leads to?
  3. What is the most common disease that causes hyperthyroidism?
  4. A condition in which symptoms include excessive thirst which may be intense or uncontrollable, may involve cravings for ice water and excessive urine volume?
  5. A condition in which the metabolism is moving very slow?

Answers: 1 = Desmopressin 2 = Cretinism 3 = Graves disease 4 = Diabetes Insipidus 5 = Hypothyroidism




References:
Lane, L, Collins, S, Harington, S, Rainforth, S, & S., J. (2010). Pharmacology and the nursing process. Mosby Inc.

Petges, Nancy RN MSN. Pharmacology : Pituitary, Thyroid and Antithyroid Agents, 2011.
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