Degarelix

Pronunciation: DEG-a-REL-ix
Class: Gonadotropin-releasing hormone antagonist

Trade Names

Firmagon
- Injection, lyophilized powder for solution 80 mg
- Injection, lyophilized powder for solution 120 mg

Pharmacology

Binds reversibly to the pituitary gonadotropin-releasing hormone (GnRH) receptors, thereby reducing the release of gonadotropin and consequently testosterone.

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Pharmacokinetics

Absorption

C _max and AUC are approximately 26 ng/mL and 1,054 ng•day/mL, respectively. T _max is 2 days. Pharmacokinetics are strongly influenced by the injection concentration.

Distribution

Vd after IV (more than 1 L/kg) or subcutaneous (more than 1,000 L) administration indicates drug distribution throughout total body water. Plasma protein binding is approximately 90%.

Metabolism

Metabolism is due to peptide hydrolysis during hepatobiliary system passage.

Elimination

Excretion is primarily as peptide fragments in the feces (70% to 80%) and approximately 20% to 30% is renally excreted. Median terminal half-life is approximately 53 days. Cl is approximately 9 L/h.

Special Populations

Patients with hepatic function impairment were excluded from trials.

No pharmacokinetic studies have been performed.

Indications and Usage

Treatment of advanced prostate cancer.

Contraindications

Women who are or may become pregnant; hypersensitivity to any component of the product.

Dosage and Administration

Subcutaneous Start with 240 mg given as 2 injections of 120 mg at a concentration of 40 mg/mL. The maintenance dose is 80 mg as 1 injection at a concentration of 20 mg/mL.

General Advice

• Administer the first maintenance dose 28 days after the starting dose.
• Administer as a subcutaneous dose in the abdominal region, varying the site periodically.
• Inject into areas of the abdomen that will not be exposed to pressure (eg, not close to the waistband).
• Gloves should be worn during preparation and administration.
• Keep vial vertical at all times.
• Do not shake the vial.
• Do not reconstitute with bacteriostatic water for injection.
• Administer within 1 h after reconstitution with sterile water for injection.

Storage/Stability

Store at 59° to 86°F.

Drug Interactions

None well documented.

Laboratory Test Interactions

Because suppression of the pituitary gonadal system may occur, results of diagnostic test of the pituitary gonadotropic or gonadal functions may be affected.

Adverse Reactions

Cardiovascular

Hot flashes (26%); hypertension (7%).

CNS

Fatigue (6%); asthenia, dizziness, headache, insomnia (1% to 5%).

GI

Diarrhea (at least 1%); constipation (5%); nausea (1% to 5%);.

Genitourinary

Urinary tract infection (5%); erectile dysfunction, gynecomastia, testicular atrophy (at least 1%).

Hypersensitivity

Anti-degarelix antibodies (10%).

Lab Tests

Increased gamma-glutamyl transpeptidase, increased transaminase (10%).

Local

Pain (28%); erythema (17%); swelling (6%); induration (4%); nodule (3%).

Metabolic-Nutritional

Increased weight (11%).

Musculoskeletal

Back pain (6%); arthralgia (5%).

Miscellaneous

Chills (5%); fever, night sweats (1% to 5%); hyperhidrosis (at least 1%), decreased bone density.

Precautions

Pregnancy

Category X .

Lactation

Undetermined.

Children

Safety and efficacy not established.

Renal Function

Use with caution in patients with CrCl less than 50 mL/min.

Hepatic Function

Use with caution in patients with severe hepatic dysfunction.

QT/QTc interval

Long-term androgen deprivation therapy prolongs the QT interval. Consider whether the benefits of androgen deprivation therapy outweigh the potential risks in patients with congenital long QT syndrome, electrolyte abnormalities, or CHF and patients taking class 1A (eg, procainamide, quinidine) or class III (eg, amiodarone, sotalol) antiarrhythmic agents.

Overdosage

Symptoms

Has not been reported.

Patient Information

• Advise patients that possible adverse reactions related to therapy include redness, swelling, and itching at the injection site.
• Advise patients that adverse reactions related to therapy are usually mild and self-limiting, and decrease within 3 days.

Copyright © 2009 Wolters Kluwer Health.