Endocrine System Drugs Notes

Major Endocrine Glands

  • Male: Neuroendocrine system, Pituitary gland, Pineal gland, Thyroid gland, Adrenal gland, Pancreas, Testis
  • Female: Neuroendocrine system, Pituitary gland, Pineal gland, Thyroid gland, Adrenal gland, Pancreas, Ovary
  • Endocrine and nervous system work together to maintain homeostasis and respond to the environment.

Endocrine Function

  • The endocrine system regulates growth and development, energy use, electrolyte balance, and response to stressors.

Endocrine Structure

  • Glands produce and secrete hormones directly into the bloodstream.
  • Hormones attach to receptor sites to increase or decrease cellular function and are broken down immediately.
  • Hormones work by reacting with specific receptor sites on the cell or entering the cell and reacting with a receptor site inside the cell.
  • Over or underproduction of hormones affects body activities.

Thyroid Gland

  • Produces three hormones: Triiodothyronine (T3), Thyroxine (T4), and Calcitonin.
  • Thyroid hormones regulate metabolism, heat production, body temperature, oxygen consumption, cardiac output, blood volume, and metabolism of carbohydrates, fats, and proteins, as well as growth and development.
  • TH production and release are regulated by TSH through a negative feedback loop.
  • Thyroid dysfunction includes hypothyroidism and hyperthyroidism.

Hypothyroidism

  • Lack of thyroid hormones due to absence of thyroid gland, lack of iodine, lack of functioning thyroid tissue, lack of TSH, or lack of TRH.
  • Conditions include myxedema and myxedema coma.

Hyperthyroidism

  • Excessive amounts of thyroid hormone, including Grave's disease, overstimulation from TSH, and thyroid storm.

Drug Therapy for Thyroid Disorders

  • Hyperthyroidism: Goal is to reduce thyroid hormone using antithyroid drugs or surgical removal.
  • Hypothyroidism: Goal is thyroid hormone replacement; monitor TSH.

Antithyroid Drugs

  • Example: Propylthiouracil (PTU).
  • Action: Inhibits production of thyroid hormone.
  • Use: Hyperthyroidism.
  • Adverse Effects: Hypothyroidism, bone marrow suppression, and liver failure.

Misc. Anti-thyroid drugs

  • Iodine solutions (e.g., Lugol's solution) are used before surgery to reduce the size and vascularity of the thyroid gland.
  • Not safe in pregnancy and may discolor teeth.

Thyroid Drugs

  • Example: Levothyroxine.
  • Action: Synthetic T4, increases metabolic rate.
  • Use: Hypothyroidism and thyroid cancer.
  • Adverse effects: Hyperthyroidism, tachycardia and MI.

Pituitary & Hypothalamic Dysfunction

  • Hypothalamus: Constantly monitors the body’s homeostasis and coordinates responses through the autonomic, endocrine, & nervous systems.

Anterior Pituitary Hormone Actions

  • Corticotropin (ACTH): Stimulates production of corticosteroids
  • Growth Hormone AKA Somatotropin (GH): Stimulates growth of body tissues

Posterior Pituitary Hormone Actions

  • Antidiuretic Hormone AKA Vasopressin (ADH): Regulates water balance

Pituitary & Hypothalamic Dysfunction

  • Diabetes Insipidus: Dysfunction of posterior pituitary and deficiency in ADH production.
  • Acromegaly/Gigantism: r/t excess growth hormone.

Drug Therapy for Growth Deficiency

  • Example: Somatropin
  • Action: Replaces Growth Hormone, stimulates bone/muscle growth

Drug Therapy for Diabetes Insipidus

  • Example: Desmopressin (DDAVP)
  • Action: Synthetic ADH, decreases urine volume

Drug Therapy for Precocious Puberty

  • Example: Leuprolide
  • Action: Inhibits gonadotropin secretion: suppressing LH and FSH, decreasing testosterone in males

Drug Therapy for Acromegaly

  • Example: Octreotide
  • Action: mimics somatostatin, inhibiting GH, insulin & some GI hormones

Drug Therapy To Regulate Calcium and Bone Metabolism

  • Parathyroid Glands: Located ON back of thyroid gland and Produces parathyroid hormone (PTH)
  • Calcium Regulation:
    • Parathyroid hormone
    • Calcitonin
    • Vitamin D

Disorders of the Parathyroid glands

  • Hypoparathyroidism: Not enough PTH and Low calcium levels
  • Hyperparathyroidism: Too much PTH and High calcium levels

Treatment for Hypocalcemia

  • Calcium supplements: calcium acetate, calcium carbonate (tums), calcium citrate, calcium gluconate
  • Action: Provides supplemental calcium and Used to Treat & prevent hypocalcemia

Treatment for Hypercalcemia

  • Bisphosphonates: Example: Alendronate
  • Action: bind to bone and block calcium release, suppress osteoclasts

Drug Therapy for Addison's and Cushing's Disease

  • Adrenal Glands: Located on top of each kidney

Adrenocortical Hormones

  • Glucocorticoids: Immune response
  • Mineralocorticoids: Water & electrolyte balance
  • Androgens: Male/Female reproductive

Adrenal Insufficiency- Addison’s Disease

  • Lack of adrenocortical hormones and Lack of ACTH

Adrenocortical Excess- Cushing's Disease

  • Cushing's Disease: Excess Adrenocortical hormones

Drug Therapy for Addison’s Disease

  • Example: Hydrocortisone
  • Action: combo mineralocorticoid & glucocorticoid, decreases inflammatory response, and increases retention of Na

Drug Therapy for Addison’s Disease

  • Example: Fludrocortisone
  • Action: Strong mineralocorticoid action, Na retention & K excretion (increased BP)

Drug Therapy for Cushing’s Disease

  • Example: Ketoconazole
  • Action: Inhibits cortisol synthesis