degarelix

Therapeutic Classification: antineoplastics

Pharmacologic Classification: gnrh antagonist

Indications ⬆ ⬇

High Alert

Advanced prostate cancer.

Action ⬆ ⬇

Reversibly binds to gonadotropin-releasing hormone receptors in the pituitary gland, causing a decrease in the release of gonadotropins and testosterone.

Therapeutic effects:

Decreased spread of prostate cancer.

Pharmacokinetics ⬆ ⬇

Absorption: Rapid release initially, then slow release from depot formed after SUBQ administration.

Distribution: Distributed throughout total body water.

Metabolism/Excretion: 70–80% undergoes hepatic metabolism and biliary excretion, most metabolites excreted in feces; 20–30% excreted unchanged in urine.

Half-Life: 53 days.

Time/Action Profile ⬆ ⬇

(↓ in testosterone levels)

ROUTE	ONSET	PEAK	DURATION
SC	within 1 wk	2 wk	1 mo

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Previous hypersensitivity.

Use Cautiously in:

Severe renal impairment;
Severe hepatic impairment;
Previous history of cardiovascular disease including congenital long QT syndrome, electrolyte abnormalities, or HF, or concurrent use of class IA or class III antiarrhythmics (may ↑ the risk of QT prolongation);
Pedi: Safety and effectiveness not established in children;
Geri: Older adults may be more sensitive to drug effects.

Adv. Reactions/Side Effects ⬆ ⬇

CV: QT interval prolongation

Derm: ↑sweating

Endo: hot flashes, gynecomastia, pituitary gonadal suppression

GI: ↑liver enzymes, diarrhea, nausea

GU: ↓fertility, erectile dysfunction, testicular atrophy

Local: injection site reactions

Metab: weight gain

MS: ↓bone density

Neuro: dizziness, headache, insomnia, weakness

Misc: fever, HYPERSENSITIVITY REACTIONS (INCLUDING ANAPHYLAXIS AND ANGIOEDEMA)

Interactions ⬆ ⬇

Drug-drug:

Concurrent use with class IA antiarrhythmics, including procainamide and quinidine, or class III antiarrhythmics, including amiodarone or sotalol, may ↑ risk of QT interval prolongation and serious arrhythmias.

Route/Dosage ⬆ ⬇

SC (Adults ): 240 mg initially (given as two injections of 120 mg each) (loading dose), followed by maintenance dose of 80 mg every 28 days.

Availability ⬆ ⬇

Powder for SUBQ injection: 80 mg/vial; 120 mg/vial

Assessment ⬆ ⬇

Assess patient for hot flashes and other side effects.
Monitor for signs and symptoms of hypersensitivity reactions (rash, wheezing, shortness of breath). Treat symptomatically and discontinue degarelix if symptoms occur.
Monitor ECG periodically during therapy, especially in patients with congenital long QT syndrome, HF, or frequent electrolyte abnormalities and in patients taking drugs known to prolong QT interval.

Lab Test Considerations:

Measure serum prostate-specific antigen (PSA) periodically to determine effect. If PSA ↑, measure serum testosterone concentrations.
- May affect pituitary gonadotropic or gonadal functions.
- Monitor electrolyte levels periodically during therapy; correct abnormalities.
- May cause ↓ bone density.

Implementation ⬆ ⬇

SC: Reconstitution: Reconstitute each 120-mg vial with 3 mL and each 80-mg vial with 4.2 mL sterile water using 21 gauge, 2-inch reconstitution needle. Keep vial upright and swirl very gently until liquid is clear, without undissolved powder or particles. If powder adheres to vial over the liquid surface, vial can be tilted slightly to dissolve powder. Avoid shaking to prevent foam; ring of small air bubbles on surface of liquid is acceptable. Tilt vial slightly, keeping needle in lowest part of vial, and withdraw 3 mL for 120-mg dose or 4 mL for 80-mg dose. Exchange reconstitution needle for 27 gauge, 1¼-inch administration needle. Remove air bubbles. Grasp abdominal skin and insert needle deeply at angle not <45°. Inject in an area free of pressure from belts, waistbands, or other types of clothing. Administer immediately, within 1 hr, after reconstitution. If administering 240-mg loading dose, repeat 120-mg injection for the 2nd dose.

Patient/Family Teaching ⬆ ⬇

Explain purpose of medication to patient. Instruct patient to notify health care professional if an injection is missed. Advise patient to read Patient Informationbefore starting and with each Rx refill in case of changes.
Inform patient of possible side effects (hot flashes, flushing, increased weight, decreased sex drive, erectile dysfunction). Advise patient that redness, swelling, and itching at injection site are usually mild and self-limiting and should decrease within 3 days.
Instruct patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and consult health care professional before taking any new medications.
Rep: May impair fertility in males.

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Pronunciation ⬇

Classifications ⬆ ⬇