How Do Antineoplastic GNRH Antagonists Work?

Antineoplastic gonadotropin-releasing hormone (GnRH) antagonists are a class of drugs used to treat advanced prostate cancer. GnRH antagonists work by decreasing the amount of testosterone (a male hormone) produced by the body. This may slow or stop the spread of prostate cancer cells that need testosterone to grow.

GnRH hormone is produced by the hypothalamus (a part of the brain) that further stimulates the pituitary gland to produce luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These hormones when released in the blood stimulate the production of testosterone by the testes in men and estrogens by the ovaries in women. GnRH antagonists block the pituitary gland from producing FSH and LH which in turn leads to inhibition of testosterone secretion, thus reducing the size of the prostate cancer.

GnRH antagonists are administered as a powder to be mixed with liquid and injected under the skin in the stomach area, away from the ribs and waistline, and orally once daily with or without food.

GnRH antagonists work in the following ways:

• They work by reducing the amount of testosterone that the body produces which helps in slowing down or halting the growth of cancer cells.
• They decrease the amount of LH and FSH hormones in the body by stimulating the pituitary gland via a negative feedback mechanism.
• They bind to GnRH receptors in the pituitary gland and block interaction with GnRH.
• This antagonism reduces LH and FSH which ultimately causes testosterone suppression.
• Reduction in testosterone is important in treating men with advanced prostate cancer.

Antineoplastic GnRH antagonists are used to treat hormone-dependent advanced prostate carcinoma.

Some of the common side effects include:

• Nausea
• Vomiting
• Constipation
• Diarrhea
• Headache
• Hot flashes
• Decreased sexual interest
• Tiredness/weakness
• Back pain
• Increased sweating
• Loss of appetite
• Joint/muscle pain
• Pain, redness, swelling, hardness, or itching at the injection site

Other rare side effects include:

• Dizziness 
• Depression
• Fatigue 
• Chest pain/tightness
• Insomnia 
• Shortness of breath
• Chills, sore throat, fever, or cough
• Blurred vision
• Painful or difficult urination
• Unusual weight gain
• Gynecomastia (breast enlargement in men)
• Rash/hives/itching
• Swelling of the face, eyes, mouth, throat, tongue, or lips
• Weight gain
• Hypertension (high blood pressure)
• Hyperglycemia (high blood glucose level)
• Elevated liver enzymes

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Generic and brand names of antineoplastic GnRH antagonists include:

• Degarelix
• Firmagon
• Orgovyx
• Relugolix