Degarelix – Uses, Dosage, Side Effects, Interaction

Degarelix Acetate is the acetate form of a long-acting, synthetic peptide with gonadotrophin-releasing hormone (GnRH) antagonistic properties. Degarelix targets and blocks GnRH receptors located on the surfaces of gonadotroph cells in the anterior pituitary, thereby reducing the secretion of luteinizing hormone (LH) by pituitary gonadotroph cells and so decreasing testosterone production by interstitial (Leydig) cells in the testes.

Mechanism of Action

Degarelix competitively inhibits GnRH receptors in the pituitary gland, preventing the release of luteinizing hormone (LH) and follicle-stimulating hormone. Reduced LH suppresses testosterone release, which slows growth and reduces the size of prostate cancers.

Degarelix is a selective gonadotrophin-releasing-hormone (GnRH) antagonist that competitively and reversibly binds to the pituitary GnRH receptors, thereby rapidly reducing the release of the gonadotrophins, luteinizing hormone (LH) and follicle stimulating hormone (FSH), and thereby reducing the secretion of testosterone (T) by the testes. Prostatic carcinoma is known to be androgen-sensitive and responds to treatment that removes the source of androgen. Unlike GnRH agonists, GnRH antagonists do not induce an LH surge with subsequent testosterone surge/tumor stimulation and potential symptomatic flare after the initiation of treatment

or

Degarelix, a synthetic decapeptide, is a gonadotropin-releasing hormone (GnRH, luteinizing hormone-releasing hormone, gonadorelin) antagonist. The drug immediately, competitively, and reversibly binds to and blocks GnRH receptors in the pituitary, thereby reducing the release of gonadotropins (i.e., luteinizing hormone [LH], follicle-stimulating hormone [FSH]) and, consequently, testosterone without initial stimulation of the hypothalamic-pituitary-gonadal axis and the associated testosterone surge. Degarelix appears to have low histamine-releasing potential compared with other GnRH antagonists; there have been no signs of immediate- or late-onset systemic allergic reactions with degarelix. Degarelix is a synthetic derivative of GnRH decapeptide, the ligand of the GnRH receptor. Gonadotropin and androgen production result from the binding of endogenous GnRH to the GnRH receptor. Degarelix antagonizes the GnRH receptor which in turn blocks the release of LH and FSH from the pituitary. LF and FSH decrease in a concentration-dependent manner. The reduction in LH leads to a decrease in testosterone release from the testes.

Gonadotrophin-releasing hormone receptors, GnRH1 and GnRH2 receptors (provisional nomenclature, also called Type I and Type II GnRH receptor, respectively ) have been cloned from numerous species, most of which express two or three types of GnRH receptor. GnRH I (p-Glu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2) is a hypothalamic decapeptide also known as luteinizing hormone-releasing hormone, gonadoliberin, luliberin, gonadorelin or simply as GnRH. It is a member of a family of similar peptides found in many species including GnRH II (pGlu-His-Trp-Ser-His-Gly-Trp-Tyr-Pro-Gly-NH2 (which is also known as chicken GnRH-II). Receptors for three forms of GnRH exist in some species but only GnRH I and GnRH II and their cognate receptors have been found in mammals. GnRH1 receptors are expressed by pituitary gonadotrophs, where they mediate the effects of GnRH on gonadotropin hormone synthesis and secretion that underpin central control of mammalian reproduction. GnRH analogs are used in assisted reproduction and to treat steroid hormone-dependent conditions. Notably, agonists cause desensitization of GnRH-stimulated gonadotropin secretion, and the consequent reduction in circulating sex steroids is exploited to treat hormone-dependent cancers of the breast, ovary, and prostate. GnRH1 receptors are selectively activated by GnRH I and all lack the COOH-terminal tails found in other GPCRs. GnRH2 receptors do have COOH-terminal tails and (where tested) are selective for GnRH II over GnRH I. GnRH2 receptors are expressed by some primates but not by humans. Phylogenetic classifications divide GnRH receptors into three or five groups and highlight examples of gene loss through evolution, with humans retaining only one ancient gene. The structure of the GnRH1 receptor in complex with elagolix has been elucidated.

Indications

  • Degarelix is used for the management of advanced prostate cancer.
  • FIRMAGON is a gonadotrophin-releasing hormone (GnRH) antagonist indicated for the treatment of adult male patients with advanced hormone-dependent prostate cancer for treatment of high-risk localized and locally advanced hormone-dependent prostate cancer in combination with radiotherapy as a neo-adjuvant treatment prior to radiotherapy in patients with high-risk localized or locally advanced hormone dependent prostate cancer.
  • Degarelix is a parenterally administered, gonadotropin-releasing hormone (GnRH) antagonist that effectively blocks androgen production and is used to treat advanced prostate cancer.
  • Intended to treat patients with advanced prostate cancer … slows the growth and progression of prostate cancer by suppressing testosterone

Use in Cancer

Degarelix is approved to treat:

Contraindications

  • low amount of magnesium in the blood
  • low amount of potassium in the blood
  • prolonged QT interval on EKG
  • chronic heart failure
  • abnormal EKG with QT changes from birth
  • liver problems
  • decreased calcification or density of bone
  • pregnancy

Dosage

Strengths: 80 mg; 120 mg

Prostate Cancer

  • Initial Dose: 240 mg administered as 2 subcutaneous injections of 120 mg each at a concentration of 40 mg/mL.
  • Maintenance Dose: 80 mg administered as 1 subcutaneous injection at a concentration of 20 mg/mL every 28 days.
  • Administer the first maintenance dose 28 days after the initial dose.

Renal Dose Adjustments

  • Mild Renal Impairment (CrCl 50 to 80 mL/min): No adjustment recommended.
  • Moderate to Severe Renal Impairment (CrCl less than 50 mL/min): Use with caution.

Liver Dose Adjustments

  • Mild to Moderate Hepatic Impairment (Child-Pugh A and B): No adjustment recommended.
  • Severe Hepatic Impairment (Child-Pugh C): Data not available; use with caution.

Administration Advice:

  • Administer this drug in the abdominal region only.
  • Vary the injection site periodically to minimize patient discomfort, and administer in abdomen areas not exposed to pressure (e.g., not close to the waistband or belt, not close to the ribs).
  • Perform a slow, deep subcutaneous injection over 30 seconds.
  • This drug is for subcutaneous injection only; do not administer intravenously or intramuscularly.
  • Use this drug only as a first-line androgen deprivation therapy; there is no data available on the use of this drug in patients who have failed treatment with GnRH agonists (e.g., leuprorelin, goserelin).
  • Confirm serum testosterone levels are remaining sufficiently suppressed if a patient’s clinical response appears to be sub-optimal.

Side Effects

The Most Common

  • pain, redness, swelling, hardness, or itching in the place where the medication was injected
  • hot flashes
  • excessive sweating or night sweats
  • nausea
  • constipation
  • diarrhea
  • weight gain or loss
  • weakness
  • dizziness
  • headache
  • tiredness
  • difficulty falling asleep or staying asleep
  • enlargement of the breasts
  • decreased sexual desire or ability
  • back or joint pain
  • hives
  • rash
  • difficulty breathing or swallowing
  • rapid, irregular, or pounding heartbeat
  • swelling of the face, throat, tongue, lips, eyes, hands, feet, ankles, or lower legs
  • hoarseness
  • fluttering feeling in the chest
  • fainting
  • painful, frequent, or difficult urination
  • fever or chills

More common

  • Back pain
  • blurred vision
  • dizziness
  • fever
  • flushing or redness of the skin
  • hard lump
  • headache
  • nervousness
  • pain
  • pounding in the ears
  • slow or fast heartbeat
  • small lumps under the skin
  • swelling
  • unusually warm skin
  • fast or pounding heartbeats, fluttering in your chest;
  • shortness of breath;
  • sudden dizziness (like you might pass out); or
  • severe headache, blurred vision, and pounding in your neck or ears.
  • hot flashes;
  • abnormal liver function tests; or
  • pain, swelling, redness, itching, or a hard lump where the medicine was injected.
  • weight gain;

Rare

  • Bladder pain
  • bloody or cloudy urine
  • chills
  • decrease in testicle size
  • decreased interest in sexual intercourse
  • difficult, burning, or painful urination
  • difficulty in moving
  • frequent urge to urinate
  • inability to have or keep an erection
  • increased sweating
  • loss in sexual ability, desire, drive, or performance
  • lower back or side pain
  • muscle pain or stiffness
  • pain in the joints
  • Chest pain or discomfort
  • fainting
  • irregular heartbeat
  • pounding heartbeat
  • Cough
  • difficulty swallowing
  • hives, itching, or skin rash
  • puffiness or swelling of the eyelids or around the eyes, face, lips or tongue
  • tightness in the chest
  • trouble breathing
  • unusual tiredness or weakness

Drug Interaction

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Pregnancy and Lactation

FDA Pregnancy Risk Category: X 

AU TGA pregnancy category D

Pregnancy

There are no controlled data on human pregnancy. Drugs that have caused, are suspected to have caused, or may be expected to cause, an increased incidence of human fetal malformations or irreversible damage. These drugs may also have adverse pharmacological effects. Studies in animals or humans have demonstrated fetal abnormalities and/or there is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience, and the risks involved in the use of the drug in pregnant women clearly outweigh the potential benefits.

Lactation

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

How should this medicine be used?

Degarelix injection comes as a powder to be mixed with liquid and injected under the skin in the stomach area, away from the ribs and waistline. It is usually injected once every 28 days by a doctor or nurse in a medical facility.

After you receive a dose of degarelix injection, be sure that your belt or waistband does not put pressure on the place where the medication was injected.

Ask your pharmacist or doctor for a copy of the manufacturer’s information for the patient.

Other uses for this medicine

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

What special precautions should I follow?

Before receiving degarelix injection,

  • tell your doctor and pharmacist if you are allergic to degarelix injection, any other medications, or any of the ingredients in degarelix injection. Ask your pharmacist or check the patient’s information for a list of the ingredients.
  • tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: amiodarone (Cordarone), disopyramide (Norpace), quinidine, procainamide, or sotalol (Betapace). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
  • tell your doctor if you have or have ever had long QT syndrome (a rare heart problem that may cause irregular heartbeat, fainting, or sudden death); high or low levels of calcium, potassium, magnesium, or sodium in your blood; or heart, liver, or kidney disease.
  • women who are or who may become pregnant should not receive degarelix injections. Degarelix injection may harm the fetus. If you receive degarelix injection while you are pregnant, call your doctor immediately. If you are breastfeeding, talk to your doctor before you receive degarelix injection.

References

  1. https://www.accessdata.fda.gov/drugsatfda_docs/label/2008/022201lbl.pdf
  2. https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/022201s011lbl.pdf
  3. https://www.accessdata.fda.gov/drugsatfda_docs/psg/PSG_022201.pdf
  4. https://www.cancer.gov/about-cancer/treatment/drugs/degarelix
  5. https://pubchem.ncbi.nlm.nih.gov/compound/Degarelix
  6. https://pubchem.ncbi.nlm.nih.gov/compound/Degarelix-acetate-hydrate
  7. https://www.drugs.com/degarelix.html
  8. https://go.drugbank.com/drugs/DB06699
  9. https://en.wikipedia.org/wiki/Degarelix
  10. https://medlineplus.gov/druginfo/meds/a609022.html
  11. https://www.webmd.com/drugs/2/drug-151919/degarelix-subcutaneous/details/list-contraindications
  12. https://www.mayoclinic.org/drugs-supplements/degarelix-subcutaneous-route/side-effects/drg-20072529?
  13. NCI Thesaurus Tree
  14. ChemIDplus Chemical Information Classification
  15. CompTox Chemicals Dashboard Chemical Lists
  16. Guide to Pharmacology Target Classification
  17. PubChem
  18. Anatomical Therapeutic Chemical (ATC) classification
    Target-based classification of drugs
  19. NORMAN Suspect List Exchange Classification
  20. NCBI