Degarelix (Subcutaneous)

Sold and marketed under the brand name Firmagon, degarelix is considered a first-line treatment for men with moderate and advanced prostate cancer which functions by suppressing the creation and release of the hormone testosterone that the cancerous cells rely on for continued growth.

Overview

Degarelix is a relatively new drug used in chemotherapy for the treatment of prostate cancer in men. It has been available since 2008 and is sold under the brand name Firmagon. It is a gonadotropin-releasing hormone receptor agonist which functions in the body to suppress the production of the hormone testosterone. It does this by binding to the GnRH receptor neurons located in the pituitary gland. In most cases of prostate cancer, the tumors are fed and grow through testosterone, and so suppressing that hormone effectively reduces the size of the tumor over time.

This medication is given as an injection once a month until the tumors have responded and are either starved to death or have reduced so much in size as to be effectively cured.

As with any effective medication, degarelix has some significant side effects. It interacts directly and significantly with at least 50 medications, and more moderately with another 195. In total, it has some level of impact on 251 different drugs. Patients with irregular heartbeat or a condition called "Long QT Syndrome" need to especially careful when taking degarelix as it reduces the effectiveness of beta-blockers and other medications prescribed for that condition. This can lead to cardiac arrest or other serious cardiac events, some of which may be fatal.

Patients with reduced liver or kidney function may also have issues with degarelix and its interaction with medications prescribed to treat those conditions. Physicians and patients need to consult and plan the treatment protocols in these cases very carefully and be sure to include plans for frequent monitoring of those other organ systems.

Because of the suppression of testosterone, use of Firmagon does carry significant sexual side effects including impotence, erectile dysfunction, loss of libido and decreased testicle size.

Patients and physicians should handle this medication with great care. It is very dangerous for women, especially if they are pregnant. Nursing mothers should also avoid contact with Firmagon.

Conditions treated

  • prostate cancer
  • medical castration

Type of medication

  • gonadotropin-releasing hormone receptor antagonist

Side effects

Degarelix (Firmagon) is a powerful medication with many possible side effects. Some of the most common include:

  • nausea
  • fatigue
  • chills
  • irregular heartbeat
  • dizziness
  • back pain
  • blurry vision
  • fever
  • muscle weakness
  • joint pain
  • nervousness or increased anxiety
  • infection of the urinary tract
  • unusual sweating
  • weight gain
  • headache
  • reactions at the site of injection particularly pain, swelling or lump
  • excessive flushing and hot flashes
  • night sweats
  • hypotension
  • constipation
  • insomnia

Other side effects that are a less common may include:

  • decreased size of testicles
  • blood in the urine
  • erectile dysfunction
  • cloudy urine
  • need to urinate more frequently
  • difficulty urinating
  • loss of interest in sex
  • sexual dysfunction
  • painful urination
  • difficulty moving

Very rare, but more significant, the following side effects require medical attention:

  • fainting (syncope)
  • heart palpitations
  • shortness of breath
  • discomfort in the chest
  • chest pain
  • possible allergic reaction/anaphylaxis

Dosage

Degarelix is given to cancer patients in the form of an injection. It is delivered to medical facilities in powder form and is then reconstituted into solution form. Firmagon is given initially as two subcutaneous injections of 120mg each for a total of 240mg. Following initial treatment, patients are given a maintenance injection every 28 days at a dosing level of 80mg. The injection is given in the abdomen.

The medical professional giving the injections should vary the site of injection around the abdomen area to avoid causing too much irritation, pain or allergic reaction at the injection site. It should only be administered subcutaneously in that region of the body. It should never be administered intravenously or directly into the muscle. The medical professional should pinch abdominal tissue between gloved fingers and insert the needle at a 45-degree angle.

Degarelix has also been tested and used in limited trials as a form of medical castration. The protocol for this treatment is an initial dose of 240mg (given in two injections). The follow-up treatment to maintain testosterone suppression is monthly injections at 160mg.

There has been no testing on the use of degarelix in patients with renal or hepatic impairment. Patients who suffer from these conditions and their physicians should proceed in use of this medication with caution, monitoring liver or kidney function often. Women should have no contact with this medication, and women who are pregnant should use extra precaution to ensure they do not come into direct contact with Firmagon, as it could be harmful to the mother and the fetus.

Interactions

Degarelix (Firmagon) has shown to interact with many other medications. It has proven to have a moderate interaction with over 190 medications, both generic and brand name. It has significant interaction with 50 drugs. These interactions include:

  • amiodarone
  • arsenic trioxide
  • lumefantrine
  • anagrelide
  • bepridil
  • bedaquiline
  • clozapine
  • ceritinib
  • citalopram
  • cisapride
  • crizotinib
  • fentanyl
  • dofetilide
  • dextromethorphan / quinidine
  • disopyramide
  • dronedarone
  • dolasetron
  • efavirenz
  • escitalopram
  • tenofevir
  • emtricitabine
  • fingolimod
  • grepafloxacin
  • gatifloxacin
  • haloperidol
  • halofantrine
  • ivabradine
  • ibutilide
  • iloperidone
  • mesoridazine
  • levomethadyl acetate
  • mifepristone
  • moxifloxacin
  • panobinostat
  • nilotinib
  • osimertinib
  • pimoride
  • papaverine
  • procainamide
  • pasireotide
  • sparfloxacin
  • saquinavir
  • thioridazine
  • saquinvir
  • toremifene
  • sotalol
  • vemurafenib
  • vandetanib
  • ziprasidone

Degarelix also interacts more moderately with over the counter pain medications such as acetaminophen and aspirin. It may reduce the effectiveness of magnesium-based medications taken to relieve digestive symptoms. It can impact the effectiveness of certain antibiotics like erythromycin, and some medications prescribed for congestion and respiratory conditions such as fluticasone and albuterol. Patients who are currently taking these sorts of medicines need to be sure to inform their physicians so that an overall treatment plan may be developed. Degarelix may also reduce the effectiveness of medications called beta-blockers, which help regulate heart rhythms. For patients with serious arrhythmia or who suffer from a condition called "Long QT Syndrome," this interaction can be very dangerous as an episode of the syndrome can result in cardiac arrest.

Warnings

Degarelix is very dangerous for women, particularly for pregnant women. It is very important that women who live with men being treated with Firmagon exercise extra precaution to avoid any sort of direct contact. Men receiving the injections should be aware that the medication will be excreted in urine, faeces and other bodily fluids. During the first two days after the injection, any caregiver in the household should wear rubber gloves when cleaning fluids, handling laundry or any other opportunity for direct contact with those bodily fluids.

Physicians and specialists administering the drug should also wear rubber gloves and exercise extra caution when handling degarelix.

When receiving the injection and immediately afterwards, patients should avoid wearing tight-fitting clothing or a belt or anything else that might constrict or further irritate the injection site. Patients who suffer from an irregular heartbeat, arrhythmia or "Long QT Syndrome" need to disclose this information to their treating physician so that may be factored into the treatment plan.

Patients who suffer from or have a history of liver or kidney disease should also disclose this information as it may impact their course of treatment. To ensure that the degarelix treatment is working, frequent blood tests are necessary to check for hormone levels as well as other cancer indicators.

Patients suffering from renal, hepatic, cardiac or other conditions may need other monitoring of blood, potassium levels, urine levels, and liver function to ensure the overall health of the patient as prolonged treatment progresses.

Should a patient miss a dose, he should make immediate contact with his medical provider to decide the course of treatment from that point. Overdosing is unlikely, given the method of delivery, but in the event that is suspected or too much is given in error, seek immediate emergency medical treatment.

It is possible to have an allergic reaction to degarelix. Should a patient experience allergic symptoms (swelling of the eyes, throat, or face, hives, difficulty breathing, etc), he should seek immediate medical attention.

Storage

Degarelix (Firmagon) should be stored as a powder at medical facilities in a secure place at room temperature (77 degrees Fahrenheit/25 degrees Celsius. It should never get colder than 59 degrees Fahrenheit/15 degrees Celsius or hotter than 86 degrees Fahrenheit/30 degrees Celsius to ensure effectiveness and dosage level accuracy. Once the powder has been reconstituted into the appropriate solution, it should be administered within one hour. Any residual solution should be safely and properly discarded. The injection should only be given subcutaneously, not intravenously or intramuscularly.

Summary

Available since 2008, degarelix (brand name Firmagon) is a gonadotropin-releasing hormone receptor agonist and is an effective first-line chemotherapy drug used to treat prostate cancer. It is delivered to the patient in the form of an injection. The initial dose is two injections, followed by a single monthly injection for such a period as the physician determines necessary to reduce the size of the tumor(s) causing the cancer.

Degarelix works by suppressing production of the hormone testosterone in men suffering from prostate cancer. Most tumors in the prostate grow and are fed by testosterone, so eliminating that source either eliminates the tumor completely or reduces it in size enough to put the patient in remission. Firmagon has several dangerous side effects, including interfering with medications that treat many heart conditions. It is also very likely to have serious sexual side effects, including sexual dysfunction, reduced testicle size, impotence and loss of interest.

This medication is quite powerful and should be handled with caution. Women should avoid even casual contact with this drug. There has been some limited use of Firmagon in medical castration. Dosing for this treatment varies slightly from that of prostate cancer but works in the same way. By reducing or eliminating testosterone, the male will have limited to no capacity for sexual activity.