goserelin acetate
Zoladex, Zoladex 3-month

Available forms
Available by prescription only
Implant: 3.6 mg, 10.8 mg

Indications and dosages
 Endometriosis, advanced breast carcinoma, endometrial thinning. Women: 1 (3.6-mg) implant S.C. q 28 days into the upper abdominal wall for 6 months. Treatment of endometriosis shouldn’t exceed 6 months.
 Palliative treatment of advanced carcinoma of the prostate. Men: 1 (10.8-mg) implant S.C. q 12 weeks into the upper abdominal wall.

Pharmacodynamics
Hormonal action: Long-term administration of goserelin, an LHRH, acts on the pituitary to decrease the release of follicle-stimulating hormone (FSH) and luteinizing hormone. In men, the result is dramatically decreased serum levels of testosterone.

Pharmacokinetics
Absorption: Slowly absorbed from implant site.
Distribution: Administration of the implant results in measurable levels of drug in serum throughout the dosing period.
Metabolism: Clearance of goserelin following S.C. administration of the drug is rapid and occurs via a combination of hepatic metabolism and urinary excretion.
Excretion: Elimination half-life is about 4 1/4 hours in patients with normal renal function. Substantial renal impairment prolongs half-life, but this doesn’t appear to increase the risk of adverse effects.

Contraindications and precautions
Contraindicated in patients hypersensitive to LHRH, LHRH agonist analogues, or goserelin acetate. Also contraindicated in pregnant and breast-feeding women. The 10.8-mg implant is contraindicated for use in women.
  Use cautiously in patients who take anticonvulsants or corticosteroids and those at risk for hyperlipidemia, osteoporosis, or chronic alcohol or tobacco abuse.

Interactions
None reported.

Adverse reactions
CNS: lethargy, pain (worsened in the first 30 days), dizziness, insomnia, asthenia, anxiety, depression, headache, chills, emotional lability, CVA.
CV: edema, heart failure, arrhythmias,peripheral edema, hypertension, MI, peripheral vascular disorder, chest pain.
GI: nausea, vomiting, diarrhea, constipation, ulcer, anorexia, abdominal pain.
GU: impotence, sexual dysfunction, lower urinary tract symptoms, renal insufficiency, urinary obstruction, vaginitis, urinary tract infection, amenorrhea, increased serum testosterone levels during the first week of therapy.
Hematologic: anemia.
Metabolic: increased serum acid phosphatase initially (will decrease by week 4); hyperglycemia; weight gain; increased low-density lipoprotein, high-density lipoprotein, and triglyceride levels.
Musculoskeletal: gout, back pain.
Respiratory: COPD, upper respiratory tract infection.
Skin: rash, diaphoresis, acne, seborrhea, hirsutism.
Other: changes in libido, hot flashes, infection, breast swelling and tenderness, changes in breast size, breast pain.

Effects on lab test results
• May increase LDL, HDL, triglyceride, calcium, and glucose levels.
• May decrease hemoglobin and hematocrit.

Overdose and treatment
No information is available regarding accidental or intentional overdose. In animal studies, doses up to 1 mg/kg daily produced no non-endocrine-related symptoms.

Special considerations
• Give drug every 28 days for the 3.6-mg implant and every 12 weeks for the 10.8-mg implant, always under direct medical supervision. Local anesthesia may be used before injection.
• In the unlikely event of the need to surgically remove goserelin, it may be localized by ultrasound.
• Because Zoladex may suppress the pituitary-gonadal system, diagnostic tests of the pituitary-gonadotropic and gonadal functions conducted during treatment and until resumption of menses may show results that are misleading.
Breast-feeding patients
• It isn’t known whether drug appears in breast milk.
Pediatric patients
• Safety and efficacy in children younger than age 18 haven’t been established.

Patient education
• Advise patient to report on time for each new implant.
• Advise patient to immediately report any implant-site reactions or other adverse reactions, such as those related to hypoestrogenism (hot flashes, headache, vaginal dryness, change in libido, depression, sweating, and change in breast size).

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use