Goserelin Acetate

Pronunciation: (GO-suh-REH-lin ASS-uh-TATE)Class: Gonadotropin-releasing hormone analog

Trade Names:Zoladex- Implant 3.6 mg- Implant 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 2 h in men. C _max for the 3.6 mg implant is about 1.46 ng/mL in women and 2.84 ng/mL in men and for the 10.8 mg is about 8 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

The t _{1/ 2} for the 3.6 mg implant is 4.2 h in men and 2.3 h in women. More than 90% is excreted in urine, 20% unchanged. Mean systemic Cl for the 3.6 mg implant is 111 mL/min in men and to 164 mL/min in women.

Onset

1 wk.

Peak

2 to 4 wk.

Special Populations

Renal Function Impairment

In CrCl less than 20 mL/min, the t _{1/ 2} is 12.1 h.

Increased body weight

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

Indications and Usage

Goserelin 3.6 mg implant

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

Goserelin 3.6 and 10.8 mg implants

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

Contraindications

Breast-feeding; women being treated for endometriosis or endometrial thinning who are or may become pregnant; known hypersensitivity to LHRH, LHRH agonist analogs, or any component of the product; 10.8 mg goserelin implant is not indicated in women.

Dosage and Administration

Adults 28 days

Subcutaneous 3.6 mg implant every 28 days into upper abdominal wall by sterile technique under health care provider's supervision.

Adults 12 weeks

Subcutaneous 10.8 mg implant every 12 wk into upper abdominal wall by sterile technique under health care provider's supervision.

Advanced Breast CancerAdults

Subcutaneous (3.6 mg only). Intended for long-term administration unless clinically inappropriate.

EndometriosisAdults

Subcutaneous (3.6 mg only). Current recommended duration of treatment is 6 mo.

Endometrial ThinningAdults

Subcutaneous (3.6 mg only). Recommendation is 1 or 2 depots, given 4 wk apart. When 1 depot is administered, surgery should be at 4 wk. When 2 depots are administered, surgery should be within 2 to 4 wk following the second depot.

Prostatic CarcinomaAdults

Subcutaneous (3.6 or 10.8 mg). Intended for long-term administration unless clinically inappropriate.

Stage B2 to C Prostatic CarcinomaAdults

Subcutaneous (3.6 or 10.8 mg only). When given in combination with radiotherapy and flutamide, start treatment 8 wk prior to initiating radiotherapy and continue during radiation therapy. A regimen using goserelin 3.6 mg depot 8 wk before radiotherapy, followed in 28 days by the 10.8 mg depot, can be administered. Alternatively, 4 injections of 3.6 mg depot can be administered at 28 day intervals, 2 depots preceding the 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.
• Using 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 preloaded syringe in foil pouch at controlled room temperature (less than 77°F). Do not remove syringe from foil pouch until just prior to use.

Drug Interactions

None well documented.

Laboratory Test Interactions

Diagnostic tests of pituitary-gonadotropic and gonadal functions

Results may be misleading.

Estrogen

Drug may cause initial transient increase in serum levels in women.

Hypercalcemia in patients with bone metastases

Drug may cause initial transient increase.

Testosterone

Drug may cause initial transient increases in serum levels in men.

Adverse Reactions

Cardiovascular

Women

Vasodilation (57%); migraine (7%); hypertension (6%); chest pain, hemorrhage, palpitations, tachycardia (at least 1%)

Men

CHF (5%); angina pectoris, arrhythmia, cerebral ischemia, cerebrovascular accident, chest pain, heart failure, hypertension, MI, peripheral vascular disorder, pulmonary embolus, varicose veins (greater than 1% but less than 5%).

CNS

Women

Headache (75%); emotional lability (60%); depression (54%); insomnia, asthenia (11%); dizziness (6%); fatigue, lethargy, malaise, nervousness (5%); hypertonia, abnormal thinking, anxiety, paresthesia somnolence (at least 1%).

Men

Lethargy (8%); dizziness, insomnia (5%); anxiety, depression, headache, paresthesia (greater than 1% but less than 5%).

Dermatologic

Women

Hot flashes (96%); sweating (45%); acne (42%); seborrhea (26%); hirsutism (7%); hair disorder (4%); pruritus (2%); alopecia, dry skin, ecchymosis, skin discoloration (at least 1%).

Men

Hot flashes (62%); rash, sweating (6%); herpes simplex, pruritus (greater than 1% but less than 5%).

EENT

Women

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

GI

Women

Nausea, abdominal pain (11%); vomiting (4%); increased appetite (2%); anorexia, constipation, diarrhea, dry mouth, dyspepsia, flatulence (at least 1%).

Men

Anorexia, nausea (5%); abdominal pain, constipation, diarrhea, hematemesis, ulcer, vomiting (greater than 1% but less than 5%).

Genitourinary

Women

Vaginitis (75%); decreased libido (61%); breast atrophy (33%); breast enlargement, pelvic symptoms (18%); dyspareunia (14%); increased libido (12%); breast pain, dysmenorrhea (7%); uterine hemorrhage (6%); vulvovaginitis (5%); menorrhagia (4%); urinary frequency, UTI, vaginal hemorrhage (at least 1%).

Men

Sexual dysfunction (21%); decreased erections (18%); lower UTIs (13%); bladder neoplasm, breast swelling and tenderness, hematuria, impotence, renal function impairment, urinary obstruction, urinary frequency, urinary incontinence, urinary infrequency, urinary retention, urinary tract disorder, UTI (greater than 1% but less than 5%).

Hematologic-Lymphatic

Men

Anemia (greater than 1% but less than 5%).

Hypersensitivity

Anaphylaxis.

Local

Women

Elevated liver enzymes (ALT, AST) (at least 1%).

Metabolic-Nutritional

Women

Weight gain (3%).

Men

Diabetes mellitus, gout, hyperglycemia, weight increase (greater than 1% but less than 5%); decreased bone mineral density and bony fracture in men, osteoporosis (postmarketing).

Musculoskeletal

Women

Back pain (7%); myalgia (3%); leg cramps (2%); arthralgia, joint disorder (at least 1%).

Men

Back pain (greater than 1% but less than 5%).

Respiratory

Women

Sinusitis (3%); bronchitis, epistaxis, increased cough, rhinitis (at least 1%).

Men

Upper respiratory infection (7%); chronic obstructive pulmonary disease (5%); dyspnea, increased cough, pneumonia (greater than 1% but less than 5%).

Miscellaneous

Women

Tumor flare (23%); peripheral edema (21%); pain (17%); infection (13%); flu syndrome (5%); voice alterations (3%), edema, fever (at least 1%).

Men

Pain, edema (8%); flu syndrome, sepsis, peripheral edema (greater than 1% but less than 5%).

Precautions

Monitor Testosterone/Prostatic acid phosphatase Ensure serum testosterone and prostatic acid phosphatase are periodically measured in patient being treated for prostate cancer to assess therapeutic response.

Pregnancy

Category D (breast cancer); Category X (endometriosis, endometrial thinning, 10.8 mg strength).

Lactation

Undetermined. Discontinue the drug prior to breast-feeding.

Children

Safety and efficacy not established.

Hypersensitivity

Antibody formation to goserelin has been observed. Anaphylactic reactions are possible.

Special Risk Patients

Isolated cases of spinal cord compression and ureteral obstruction have been reported in men. Use with caution in patients prone to these problems.

Bone mineral density changes

Decreases in vertebral trabecular bone mineral density have been observed; patients with certain risk factors (eg, alcohol or tobacco abuse, family history of osteoporosis) may be at additional risk.

Breast cancer worsening

Drug initially causes transient increase in estrogen. Worsening of signs and symptoms of breast cancer, such as bone pain, may occur during the first few weeks of treatment.

Prostatic cancer worsening

Drug initially causes transient increase in testosterone. Worsening of signs and symptoms of prostate cancer, such as bone pain, may occur during first few weeks of treatment.

10.8 mg implant

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

Hormone replacement therapy (HRT)

Clinical studies suggest the addition of HRT (estrogens or progestins) to goserelin may decrease the occurrence of vasomotor symptoms and vaginal dryness associated with hypoestrogenism without compromising the efficacy of goserelin in relieving pelvic symptoms. The optimal drugs, dose, and duration of treatment not established.

Hypercalcemia

Hypercalcemia has occurred in some prostate and breast cancer patients with bone metastases after starting goserelin treatment. Ensure serum calcium levels are monitored in patient being treated for prostate or breast cancer. Inform health care provider immediately if hypercalcemia is noted or patient develops signs or symptoms of hypercalcemia (eg, polyuria, confusion, drowsiness). Be prepared to treat appropriately (eg, sodium chloride 0.9% injection, furosemide).

Hypoestrogenism

Hypoestrogenism may be induced by goserelin, which results in loss of bone mineral density over the course of treatment and may be irreversible. Adverse reactions occurring with hypoestrogenism most frequently include hot flashes, headaches, vaginal dryness, emotional lability, changes in libido, depression, sweating, and change in breast size.

Pituitary gonadal axis

As with other hormonal interventions that disrupt pituitary-gonadal axis, some patients may experience a delay in return to menses and, rarely, patients may experience persistent amenorrhea.

Vaginal bleeding

Some women experience vaginal bleeding of variable duration and intensity. The bleeding represents estrogen withdrawal bleeding and is expected to stop spontaneously.

Patient Information

• Advise patient, family, or caregiver that medication will be prepared and administered by health care professionals in a health care setting.
• Advise patient, family, or caregiver that medication may be used in combination with other agents to achieve max benefit possible.
• 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.
• Caution patient that missing 1 or more doses of goserelin may result in loss of beneficial effects and to be sure to return as scheduled for additional doses of medication.
• Advise patient 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 women that the most common adverse reaction of therapy are associated with estrogen deficiency (eg, change in breast size, reduction or loss of libido, depression, emotional lability, hot flashes or flushes, sweating, vaginal dryness). Advise patient to be prepared to discuss potential value of starting hormone replacement therapy with health care provider if estrogen deficiency symptoms occur and are intolerable.
• Advise patient, family, or caregiver to immediately report any of the following to health care provider: frequent urination or little or no urination; unexplained drowsiness; lower stomach or pelvic-area pain; abnormal skin sensations; numbness or tingling sensations; loss of sphincter control; unexplained weakness; rash or hives; difficulty breathing or unexplained shortness of breath; pain, redness, or swelling at injection site.
• Advise women that menstruation should stop as a result of therapy with goserelin and to notify health care provider if regular menstruation continues. Caution patient that breakthrough menstrual bleeding and/or ovulation may occur if 1 or more does of goserelin are missed.
• 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.

Copyright © 2009 Wolters Kluwer Health.