Drugs Acting On The Endocrine System

Neuroendocrine system

Works with the nervous system to maintain internal homeostasis and integrate the body's response to the external environment.

Endocrine system functions

Regulates growth and development, reproduction, energy use, and electrolyte balance.

Glands in the endocrine system

Collections of specialized cells that secrete hormones directly into the bloodstream to act on receptor sites.

General criteria for hormones

Produced in small amounts, secreted into the bloodstream, travel to specific receptor sites, alter metabolic processes, and are quickly broken down.

Hormone action on target cells

Either by binding to receptors on the cell membrane and activating cAMP (fast effect), or entering the cell to alter DNA via mRNA (delayed effect).

Cortisol

Produced by the adrenal cortex; increases glucose levels and suppresses immune responses.

Aldosterone

Causes sodium retention and potassium excretion.

Parathyroid hormone (PTH)

Increases serum calcium by stimulating bone resorption, kidney calcium reabsorption, and vitamin D activation.

Melatonin

Regulates secretion of hypothalamic hormones, particularly GnRH.

Pancreatic hormones

Insulin, glucagon, and somatostatin for regulation of glucose and fat metabolism.

Posterior pituitary hormones

ADH (vasopressin) for water reabsorption and oxytocin for uterine contraction and milk let-down.

Anterior pituitary hormones

ACTH, TSH, GH, LH, FSH, prolactin, MSH, and lipoproteins.

Hypothalamic-pituitary axis regulation

By a negative feedback system where rising hormone levels inhibit further release from hypothalamus and pituitary.

Adrenocortical peak response

Occurs between 6-9 AM, following CRF release peaking at midnight.

Endorphins and enkephalins

Modulate pain perception.

Stimulating hypothalamic hormones

Trigger pituitary hormone release (e.g., CRH → ACTH).

Inhibiting hypothalamic hormones

Stop release (e.g., somatostatin stops GH).

Hypothalamic Hormone Agonists

Hormones that stimulate the pituitary to release target hormones.

Sample medications of Hypothalamic Hormone Agonists

Corticotropin-releasing hormone, Gonadorelin, Goserelin, Sermorelin.

Actions of Hypothalamic Hormone Agonists

Stimulate pituitary hormone release.

Indications of Hypothalamic Hormone Agonists

Diagnose Cushing's disease, treat hormone-sensitive cancers, diagnose GH deficiency, idiopathic growth failure, AIDS cachexia.

Contraindications of Hypothalamic Hormone Agonists

Hypersensitivity, pregnancy, lactation, renal impairment.

Adverse effects of Hypothalamic Hormone Agonists

Fluid retention, electrolyte imbalance, ovarian overstimulation, flushing, appetite changes.

Drug interactions of Hypothalamic Hormone Agonists

May alter metabolism of CYP450 drugs.

Nursing considerations of Hypothalamic Hormone Agonists

Monitor hormone levels, glucose, electrolytes; teach patient about adverse effects.

Hypothalamic Hormone Antagonists

Drugs that block GnRH receptors.

Sample medications of Hypothalamic Hormone Antagonists

Abarelix, Ganirelix, Leuprolide, Nafarelin.

Actions of Hypothalamic Hormone Antagonists

Block GnRH receptors → decreased LH and FSH secretion.

Indications of Hypothalamic Hormone Antagonists

Advanced prostate cancer, endometriosis, precocious puberty, fertility programs.

Contraindications of Hypothalamic Hormone Antagonists

Hypersensitivity, pregnancy, lactation.

Adverse effects of Hypothalamic Hormone Antagonists

Decreased testosterone (fatigue, low sperm count), decreased estrogen (amenorrhea, insomnia, irritability).

Nursing considerations of Hypothalamic Hormone Antagonists

Monitor sexual function, hormone levels, electrolytes.

Classification of Growth Hormone Agonists

Drugs that replace or stimulate GH.

Sample medications of Growth Hormone Agonists

Somatropin, Somatropin rDNA origin.

Actions of Growth Hormone Agonists

Stimulate growth by replacing GH.

Indications of Growth Hormone Agonists

Dwarfism, GH deficiency, Turner/Prader-Willi syndrome, idiopathic short stature, AIDS cachexia, short bowel syndrome.

Contraindications of Growth Hormone Agonists

Closed epiphyses, cranial lesions, post-surgical complications, pregnancy, lactation.

Adverse effects of Growth Hormone Agonists

Joint pain, hypothyroidism, insulin resistance, antibody formation.

Nursing considerations of Growth Hormone Agonists

Monitor growth, thyroid function, glucose tolerance; teach injection use.

Classification of Growth Hormone Antagonists

Drugs that inhibit GH secretion or block GH receptors.

Sample medications of Growth Hormone Antagonists

Bromocriptine, Octreotide, Pegvisomant.

Actions of Growth Hormone Antagonists

Inhibit GH secretion or block GH receptor binding.

Indications of Growth Hormone Antagonists

Acromegaly, gigantism (if not surgical candidates).

Contraindications of Growth Hormone Antagonists

Pregnancy, lactation, endocrine disorders.

Adverse effects of Growth Hormone Antagonists

GI upset, gallbladder disease (Octreotide); hypotension (Bromocriptine); injection pain, liver changes (Pegvisomant).

Drug interactions of Growth Hormone Antagonists

Erythromycin increases bromocriptine; opioids decrease pegvisomant effect.

Nursing considerations of Growth Hormone Antagonists

Monitor GH, glucose tolerance, thyroid function, gallbladder ultrasound.

Classification of Posterior Pituitary Hormones

ADH analogs and oxytocin.

Sample medications of Posterior Pituitary Hormones

Desmopressin, Vasopressin, Oxytocin.

Actions of Posterior Pituitary Hormones

ADH promotes water reabsorption; oxytocin stimulates uterine contractions and milk let-down.

Indications of Posterior Pituitary Hormones

Diabetes insipidus (ADH), labor induction (oxytocin).

Contraindications of Posterior Pituitary Hormones

Renal impairment, vascular disease, epilepsy, asthma, pregnancy, lactation.

Adverse effects of Posterior Pituitary Hormones

Water intoxication, electrolyte imbalance, nasal irritation, GI upset.

Drug interactions of Posterior Pituitary Hormones

Carbamazepine and chlorpropamide increase ADH effects.

Nursing considerations of Posterior Pituitary Hormones

Monitor fluid balance, electrolytes, renal function; teach signs of water intoxication.

Classification of Glucocorticoids

Adrenal cortex steroid hormones with anti-inflammatory and immunosuppressive effects.

Sample medications of Glucocorticoids

Hydrocortisone, Prednisone, Dexamethasone, Methylprednisolone, Betamethasone.

Actions of Glucocorticoids

Alter DNA transcription → anti-inflammatory, immunosuppressive.

Indications of Glucocorticoids

Addison's disease, Cushing's diagnosis, inflammatory disorders, cancers.

Contraindications of Glucocorticoids

Active infections, peptic ulcer disease, diabetes, pregnancy, lactation.

Adverse effects of Glucocorticoids

Hyperglycemia, osteoporosis, immunosuppression, ulcers, fluid retention.

Drug interactions of Glucocorticoids

Rifampin and phenytoin decrease effect; erythromycin increases effect; NSAIDs increase GI risk.

Nursing considerations of Glucocorticoids

Give AM dose, taper gradually, monitor glucose and electrolytes, avoid infection.

Classification of Mineralocorticoids

Adrenal cortex steroid hormones regulating electrolytes and water balance.

Sample medications of Mineralocorticoids

Fludrocortisone, Cortisone, Hydrocortisone.

Actions of Mineralocorticoids

Increase Na⁺ retention and K⁺ excretion.

Indications of Mineralocorticoids

Addison's disease (with glucocorticoid).

Contraindications of Mineralocorticoids

Severe hypertension, heart failure, infection, pregnancy, lactation.

Adverse effects of Mineralocorticoids

Fluid overload, hypertension, hypokalemia.

Nursing considerations of Mineralocorticoids

Monitor BP, electrolytes, fluid balance; increase dose in stress.

Classification of Thyroid Hormone Replacements

Drugs replacing thyroid hormones T3 and T4.

Sample medications of Thyroid Hormone Replacements

Levothyroxine, Liothyronine, Liotrix, Desiccated thyroid.

Actions of Thyroid Hormone Replacements

Increase metabolic rate, O₂ consumption, HR, growth.

Indications of Thyroid Hormone Replacements

Hypothyroidism, myxedema, cretinism, TSH suppression.

Contraindications of Thyroid Hormone Replacements

Acute MI, thyrotoxicosis, Addison's disease.

Adverse effects of Thyroid Hormone Replacements

Tachycardia, arrhythmias, insomnia, hair loss.

Drug interactions of Thyroid Hormone Replacements

Anticoagulants increase effect, cholestyramine decreases absorption, digoxin decreases effect.

Nursing considerations of Thyroid Hormone Replacements

Give AM before breakfast, monitor TSH/T4, cardiac function.

Classification of Antithyroid Agents

Drugs that block thyroid hormone synthesis or release.

Sample medications of Antithyroid Agents

Propylthiouracil, Methimazole, Iodine solutions.

Actions of Antithyroid Agents

Block thyroid hormone synthesis (thioamides) or release (iodine).

Indications of Antithyroid Agents

Hyperthyroidism, Graves disease, thyrotoxicosis.

Contraindications of Antithyroid Agents

Pregnancy (except PTU), lactation, pulmonary TB (iodine).

Adverse effects of Antithyroid Agents

Hypothyroidism, agranulocytosis, rash, iodism.

Drug interactions of Antithyroid Agents

Anticoagulants increase bleeding, digoxin and theophylline metabolism altered.

Nursing considerations of Antithyroid Agents

Monitor thyroid and WBC, give iodine with straw, teach to report fever/sore throat.

Classification of Antihypocalcemic Agents

Drugs that increase calcium absorption and bone formation.

Sample medications of Antihypocalcemic Agents

Calcitriol, Vitamin D analogs, Teriparatide.

Actions of Antihypocalcemic Agents

Increase calcium absorption, stimulate bone formation.

Indications of Antihypocalcemic Agents

Hypoparathyroidism, hypocalcemia, osteoporosis.

Contraindications of Antihypocalcemic Agents

Hypercalcemia, vitamin D toxicity, renal stones.

Adverse effects of Antihypocalcemic Agents

GI upset, metallic taste, hypercalcemia.

Nursing considerations of Antihypocalcemic Agents

Monitor calcium and renal function, encourage calcium/vitamin D diet.

Classification of Antihypercalcemic Agents

Drugs that lower calcium levels in blood.

Sample medications of Antihypercalcemic Agents

Bisphosphonates (Alendronate, Risedronate, Zoledronic acid), Calcitonin.

Bisphosphonates

Inhibit bone resorption.

Calcitonin

Opposes PTH.

Indications of Antihypercalcemic Agents

Hyperparathyroidism, hypercalcemia, Paget's disease, osteoporosis.

Contraindications of Antihypercalcemic Agents

Hypocalcemia, GI disease, fish allergy (calcitonin).

Adverse effects of Antihypercalcemic Agents

GI upset, esophageal erosion (bisphosphonates); flushing, nasal irritation (calcitonin).