Hypothalamic Agents

Hypothalamic agents can inhibit or stimulate the release of hormones from the anterior pituitary using hormones or factors. However, not all of these hormones are available for pharmacological use.

Stimulating factors (agonists) include growth hormone-releasing hormone (GHRH), thyrotropin-releasing hormone (TRH), gonadotropin-releasing hormone (GnRH), corticotropin-releasing hormone (CRH), and prolactin-releasing hormone (PRH).

Factors that inhibit (antagonists) include somatostatin (growth hormone-inhibiting factor) and prolactin-inhibiting factor.

Other drugs acting on the endocrine system include the following: pituitary agents, adrenocortical agents, thyroid and parathyroid agents, and agents to control blood glucose levels.

Hypothalamic Agents: Generic and Brand Names

Here is a table of commonly encountered endocrine system drugs, their generic names, and brand names:

• Stimulating factors (agonists)
  • goserelin (Zoladex)
  • histrelin (Vantas)
  • leuprolide (Lupron)
  • nafarelin (Synarel)
  • tesamorelin (Egrifta)
• Inhibiting factors (antagonists)
  • degarelix (Firmagon)
  • ganirelix (Antagon)

Therapeutic Action

The desired and beneficial action of hypothalamic agents is:

• Not clearly identified as there are only minute quantities found.
• Not all of them are used as pharmacological agents. Some are used for diagnostic purposes only and others are primarily used as antineoplastic agents.
• Tesamorelin is used to stimulate GH and its lipolytic effects, helping to decrease the excess abdominal fat in HIV-infected patients with lipodystrophy.

Indications

Hypothalamic agents are indicated for the following medical conditions:

• Hypothalamic hormones are not all available for pharmacological use; those that are available are used mostly for diagnostic testing, for treating some forms of cancer, or as adjuncts in fertility programs.
• Agonists like goserelin, histrelin, leuprolide, and nafarelin are analogues of GnRH. They decrease production of sex hormones. They are used as treatment for precocious puberty, endometriosis, and advanced prostate cancer.
• Antagonists of GnRH like degarelix and ganirelix are used as treatment for advanced prostate cancer and inhibition of premature LH surge in women undergoing controlled ovarian stimulation for fertility.

Here are some important aspects to remember for indication of hypothalamic agents in different age groups:

Children

• Monitor closely for adverse effects associated with changes in overall endocrine function, particularly growth and development and metabolism.
• Standard part of treatment plan should include periodic radiograph of long bones and monitoring of blood sugar and electrolytes.

Adults

• Monitor blood sugar and electrolytes.
• Review proper administration of nasal forms of drugs for diabetes insipidus to prevent complications.
• Review proper storage, preparation, and administration of regular injections.
• Drugs should not be used among pregnant and lactating women unless benefits clearly outweigh the risks.

Older adults

• Evaluate hydration, nutrition, and electrolyte balance periodically.
• Review proper administration technique because they are at high risk for dehydrated membranes and ulcerations.

Pharmacokinetics

Here are the characteristic interactions of hypothalamic agents and the body in terms of absorption, distribution, metabolism, and excretion:

Route	Onset	Peak	Duration
IM depot	4 h	Variable	1,2,3, or 4 mo

Half-life (T1/2)	Metabolism	Excretion
3 h	Unknown	Unknown

Contraindications and Cautions

The following are contraindications and cautions for the use of hypothalamic agents:

• Allergy to any component of the drug. To prevent hypersensitivity reactions.
• Peripheral vascular disorders. Can alter absorption of drugs.
• Rhinitis. Alters absorption of nafarelin nasal spray.
• Renal or hepatic impairment. Interfere with drug metabolism and excretion.
• Pregnancy or lactation. Potential adverse effects to fetus or neonates.

Adverse Effects

Use of hypothalamic agents may result to these adverse effects:

• Agonists: increased release of sex hormones, ovarian overstimulation, flushing, increased temperature and appetite, fluid retention
• Antagonists: decreased testosterone level, loss of energy, decreased sperm count and activity, alterations in secondary sex characteristics (decrease in female sex hormones, amenorrhea), fluid and electrolyte changes, insomnia, irritability

Interactions

Drug interactions of hypothalamic agents are related to the specific hormones that the drug is affecting. They will be discussed in detail as each agents for specific hormones will be covered in this study guide.

Nursing Considerations

The specific nursing care of patient who is receiving hypothalamic releasing factor is related to the hormone(s) that the drug is affecting. This will be discussed further as each drugs affecting certain hormones will be covered in this study guide.

Recommended Resources

Our recommended nursing pharmacology resources and books:

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See Also

Here are other nursing pharmacology study guides:

• Nursing Pharmacology – Study Guide for Nurses
  Our collection of topics related to nursing pharmacology
• Pharmacology Nursing Mnemonics & Tips
  These nursing mnemonics aim to simplify the concepts of pharmacology through the use of a simple, concise guide.
• Generic Drug Name Stems Cheat Sheet
  Learn about these generic drug name stems to help you make sense of drugs easier!
• Common Drugs and Their Antidotes
  A guide to drug antidotes that nurses should be familiar about.
• IV Fluids and Solutions Guide & Cheat Sheet
  Get to know the different types of intravenous solutions or IV fluids in this guide and cheat sheet.
• Drug Dosage Calculations NCLEX Practice Questions (100+ Items)
  Care to take the challenge? This quiz aims to help students and registered nurses alike grasp and master the concepts of medication calculation.

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• Atorvastatin (Lipitor)
• Enoxaparin (Lovenox)
• Furosemide (Lasix)
• Gabapentin
• Hydromorphone (Dilaudid)
• Lisinopril
• Metoprolol
• Morphine

References and Sources

References and sources for this pharmacology guide for Hypothalamic Agents:

• Karch, A. M., & Karch. (2011). Focus on nursing pharmacology. Wolters Kluwer Health/Lippincott Williams & Wilkins. [Link]
• Katzung, B. G. (2017). Basic and clinical pharmacology. McGraw-Hill Education.
• Lehne, R. A., Moore, L. A., Crosby, L. J., & Hamilton, D. B. (2004). Pharmacology for nursing care.
• Smeltzer, S. C., & Bare, B. G. (1992). Brunner & Suddarth’s textbook of medical-surgical nursing. Philadelphia: JB Lippincott.