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Goserelin Acetate

Pronunciation: GOE-se-REL-in AS-e-tate
Class: Gonadotropin-releasing hormone analog

Trade Names

Zoladex
- Implant, subcutaneous 3.6 mg
- Implant, subcutaneous 10.8 mg

Zoladex 3.6 mg (Canada)
Zoladex LA (Canada)

Pharmacology

Synthetic analog of gonadotropin-releasing hormone (GnRH) that acts as potent inhibitor of pituitary gonadotropin secretion.

Pharmacokinetics

Absorption

T max for the 3.6 mg implant is 12 to 15 days in men and 8 to 22 days in women. T max for the 10.8 mg implant is 1.8 h in men. C max for the 3.6 mg implant is approximately 1.46 ng/mL in women and 2.84 ng/mL in men and for the 10.8 mg is approximately 8.85 ng/mL in men.

Distribution

Vd is 44.1 L in men and 20.3 L in women. Protein binding is 27%.

Metabolism

Hydrolysis of the C-terminal amino acids.

Elimination

More than 90% is excreted in urine, 20% unchanged. Mean systemic Cl for the 3.6 mg implant is 110.5 mL/min in men and 163.9 mL/min in women. Mean systemic Cl for the 10.8 mg implant is 121 mL/min.

Special Populations

Renal Function Impairment

In patients with CrCl less than 20 mL/min, the total body Cl is 31.5 mL/min and the half-life is 12.1 h.

Hepatic Function Impairment

3.6 mg — The total body Cl and serum elimination half-lives were similar between healthy patients and patients with moderate hepatic impairment. There are no data in patients with severe hepatic insufficiency.

Elderly

Goserelin has not been studied in women older than 65 years.

Gender

The total body Cl of goserelin was significantly ( P < 0.05) greater (163.9 vs 110.5 L/min) in women compared with men.

Increased body weight

A decline in AUC of approximately 1% to 2.5% was observed with a kg increase in body weight.

Indications and Usage

Men

Palliative treatment of advanced carcinoma of the prostate; in combination with flutamide for management of locally confined stage T2b to T4 (stage B2 to C) carcinoma of the prostate.

Women (3.6 mg only)

Palliative treatment of advanced breast cancer in pre- and perimenopausal women; treatment of endometriosis; as an endometrial thinning agent prior to endometrial ablation for dysfunctional uterine bleeding.

Contraindications

Known hypersensitivity to GnRH, GnRH agonist analogues, or any of the components in goserelin; pregnancy unless goserelin is being used for palliative treatment of advanced breast cancer.

Dosage and Administration

Advanced Breast Cancer
Adults

Subcutaneous 3.6 mg every 28 days.

Advanced Prostatic Carcinoma
Adults

Subcutaneous 3.6 mg every 28 days or 10.8 mg every 12 weeks.

Endometrial Thinning
Adults

Subcutaneous 1 or 2 depot injections of 3.6 mg. If 2 depot injections are to be given, administer them 4 weeks apart. For use prior to endometrial ablation. When 1 depot is administered, perform surgery at 4 weeks. When 2 depots are administered, perform surgery within 2 to 4 weeks following administration of the second depot.

Endometriosis
Adults

Subcutaneous 3.6 mg every 28 days. Recommended duration of therapy is 6 mo. Re-treatment cannot be recommended because safety data are not available.

Stage B2 to C Prostatic Carcinoma
Adults

Subcutaneous 3.6 mg 8 weeks before radiotherapy, followed in 28 days by 10.8 mg. Alternatively, 4 injections of 3.6 mg at 28-day intervals (2 depots preceeding and 2 during radiotherapy).

General Advice

  • Dose (number or strength of implants), frequency of implantation, and duration of therapy are variable depending on condition being treated and clinical response.
  • For subcutaneous implantation only. Not for intradermal, IM, or oral administration.
  • While the delay of a few days is permissible, make every effort to adhere to the 28-day (3.6 mg) or the 12-week (10.8 mg) schedule.
  • Using a preloaded syringe with attached needle, pellets are injected into the anterior abdominal wall below the navel line.
  • Follow manufacturer's instructions regarding preparation of injection site, preparation of preloaded syringe, injection of implant, and disposal of used syringe.
  • If blood appears in syringe, do not inject implant. Instead, withdraw needle and discard syringe. Use new syringe and inject implant at a different site.
  • Pellets can be localized by ultrasound if surgical removal is necessary.

Storage/Stability

Store at controlled room temperature (less than 77°F).

Drug Interactions

None well documented.

Laboratory Test Interactions

Diagnostic tests of pituitary-gonadotropic and gonadal functions

Results may be misleading because of suppression of the pituitary-gonadal system.

Adverse Reactions

Cardiovascular

Vasodilation (57%); hypertension (6%); CHF (5%); angina pectoris, arrhythmia, cerebral ischemia, cerebrovascular accident, heart failure, MI, peripheral vascular disorder, palpitations, pulmonary embolus, tachycardia, varicose veins (greater than 1% but less than 5%); heart failure, hypotension (postmarketing).

CNS

Headache (75%); emotional lability (60%); depression (54%); asthenia, insomnia (11%); lethargy (8%); migraine (7%); dizziness (6%); fatigue/malaise, nervousness (5%); aggravation reaction, anxiety, depression, paresthesia, somnolence, thinking abnormal (greater than 1% but less than 5%); psychotic disorders (postmarketing).

Dermatologic

Hot flashes (96%); sweating (45%); acne (42%); seborrhea (26%); hirsutism (7%); rash (6%); hair disorder (4%); pruritus (2%); dry skin, herpes simplex, pruritus, skin discoloration (greater than 1% but less than 5%); alopecia (at least 1%).

EENT

Pharyngitis (6%); amblyopia, dry eyes, epistaxis (at least 1%).

GI

Abdominal pain, nausea (11%); vomiting (4%); anorexia (5%); increased appetite (2%); constipation, diarrhea, dry mouth, dyspepsia, flatulence, hematemesis, ulcer (greater than 1% but less than 5%).

Genitourinary

Vaginitis (75%); decreased libido (61%); breast atrophy (33%); sexual dysfunction (21%); breast enlargement, decreased erections, pelvic symptoms (18%); dyspareunia (14%); lower urinary tract symptoms (13%); increased libido (12%); pelvic pain (9%); gynecomastia (8%); breast pain, dysmenorrhea (7%); uterine hemorrhage (6%); vulvovaginitis (5%); menorrhagia (4%); vaginitis (1%); bladder neoplasm, breast swelling and/or tenderness, hematuria, impotence, renal insufficiency, urinary frequency, urinary incontinence, urinary obstruction, urinary retention, urinary tract disorder, urination impaired, UTI (greater than 1% but less than 5%); vaginal hemorrhage (at least 1%).

Hematologic-Lymphatic

Anemia, ecchymosis, hemorrhage (greater than 1% but less than 5%).

Hypersensitivity

Allergic reaction (at least 1% but less than 5%); hypersensitivity reactions, including urticaria and anaphylaxis (postmarketing).

Lab Tests

Elevated liver enzymes (ALT, AST) (at least 1%); increased HDL, LDL, total cholesterol, and triglycerides.

Local

Application-site reaction (6%); injection-site reactions (3%).

Metabolic-Nutritional

Peripheral edema (21%); edema (7%); weight gain (3%); diabetes mellitus, gout, hyperglycemia, weight increase (greater than 1% but less than 5%); decreased bone mineral density and bony fracture, hypercalcemia, osteoporosis, pituitary apoplexy, pituitary tumors (postmarketing).

Musculoskeletal

Back pain (7%); bone pain (6%); myalgia (3%); leg cramps (2%); arthralgia, hypertonia, joint disorder, osteoporosis (greater than 1% but less than 5%).

Respiratory

Upper respiratory tract infection (7%); COPD (5%); sinusitis (3%); bronchitis, dyspnea, increased cough, pneumonia, rhinitis (greater than 1% but less than 5%).

Miscellaneous

Tumor flare (23%); pain (17%); infection (13%); flu syndrome (5%); voice alterations (3%); chest pain, chills, fever, infection, sepsis (greater than 1% but less than 5%).

Precautions

Monitor

Monitor blood glucose and/or HbA 1c periodically. Monitor patients for the signs and symptoms suggestive of CV disease.


Pregnancy

Category D (breast cancer); Category X (endometriosis, endometrial thinning, 10.8 mg strength). Goserelin can cause fetal harm

Lactation

Undetermined. Discontinue the drug prior to breast-feeding.

Children

Safety and efficacy not established.

Hypersensitivity

Hypersensitivity, antibody formation, and acute anaphylactic reactions have been reported with GnRH agonist.

Special Risk Patients

Isolated cases of spinal cord compression and ureteral obstruction have been reported.

Antibodies

Antibody formation is possible.

Endometrial ablation

The pharmacologic action of goserelin on the uterus and cervix may cause an increase in cervical resistance. Therefore, exercise caution when dilating the cervix for endometrial ablation.

Cardiovascular effects

Increased risk of developing MI, sudden cardiac death, and stroke has been reported with the use of GnRH agonists in men.

10.8 mg implant

The 10.8 mg implant is not indicated in women because the data are insufficient to support reliable suppression of serum estradiol.

Hypercalcemia

Hypercalcemia has occurred in some prostate and breast cancer patients with bone metastases after starting goserelin treatment.

Hyperglycemia

Has been reported in men.

Tumor flare

Initially, goserelin causes transient increases in serum levels of testosterone in men with prostate cancer, and estrogen in women with breast cancer. Transient worsening of symptoms or the occurrence of additional signs and symptoms of prostate or breast cancer may occasionally develop during the first few weeks of goserelin treatment.

Patient Information

  • Advise patient that pellet is biodegradable and will be absorbed by the body and does not have to be removed when next dose is due or when therapy is discontinued.
  • Advise patients being treated for prostate or breast cancer that temporary worsening of symptoms or additional signs and symptoms of the cancer may develop during the first few weeks of therapy but should improve once the medication begins to take effect.
  • Advise patients with ureteral obstruction or spinal cord compression to have appropriate treatment prior to initiation of therapy.
  • Inform patients that diabetes or loss of glycemic control in patients with preexisting diabetes has been reported.
  • Because menstruation should stop with effective doses of goserelin, advise women to notify their health care provider if regular menstruation persists. Patients missing 1 or more successive doses of goserelin may experience breakthrough menstrual bleeding.
  • Inform pregnant women that goserelin may cause fetal harm and should not be taken during pregnancy except for the palliative treatment of breast cancer.
  • Advise women not to take goserelin if they have undiagnosed abnormal vaginal bleeding.
  • Advise women those adverse reactions occurring most frequently in clinical studies with goserelin are associated with hypoestrogenism; of these, the most frequently reported are hot flashes (flushes), headaches, vaginal dryness, emotional lability, change in libido, depression, sweating, and change in breast size.
  • Inform patient that treatment induces a hypoestrogenic state that results in a loss of bone mineral density over the course of treatment, some of which may not be reversible. Inform patients with a significant history or excessive risk for bone loss that the risks and benefits must be weighed carefully before therapy with goserelin is instituted.
  • Inform women that as with other hormonal interventions that disrupt the pituitary-gonadal axis, some patients may have delayed return to menses. The rare patient, however, may experience persistent amenorrhea.
  • Instruct women of childbearing potential to use effective nonhormonal contraception during treatment and until the return of menses or for at least 12 wk following the last pellet implantation.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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