Zoladex Goserelin Acetate Sustained-release Implant

1. Indications and Usage
Prostate Cancer: Indicated for the palliative treatment of advanced prostate cancer.
Breast Cancer: Indicated for the palliative treatment of hormone receptor-positive advanced breast cancer in pre- and perimenopausal women.
Endometriosis: Indicated for the relief of symptoms including pain and reduction in the size and number of endometrial lesions associated with endometriosis.
2. Dosage and Administration
Recommended Dosage: The recommended dosage for adults is 3.6 mg administered by deep subcutaneous injection into the anterior abdominal wall once every 28 days.
Administration: The implant must be administered by a qualified healthcare professional. It should not be used in patients with a low BMI or those receiving full-dose anticoagulation without caution to avoid penetrating major vessels or the peritoneum.
Treatment Duration: For endometriosis, treatment should generally not exceed six months due to the risk of bone mineral density loss.
3. Mechanism of Action
Goserelin acetate is a synthetic peptide analogue of the natural gonadotropin-releasing hormone (GnRH). Initially, it stimulates the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), causing a transient increase in sex steroids. With continuous administration, it downregulates and desensitizes GnRH receptors in the pituitary gland, leading to a profound suppression of LH and FSH secretion and a subsequent decrease in serum testosterone (in men) and estradiol (in women) to castrate or postmenopausal levels.
4. Safety and Warnings
Tumor Flare: In the initial weeks of treatment, there may be a transient increase in testosterone or estradiol, which can exacerbate symptoms (e.g., bone pain in prostate cancer, spinal cord compression, or hypercalcemia in metastatic breast cancer).
Bone Mineral Density: Long-term suppression of sex steroids can lead to significant bone mineral density loss and increased fracture risk.
Cardiovascular and Metabolic Risk: Gonadotropin-releasing hormone agonists may prolong the QT interval and can impair glucose tolerance, leading to worsening diabetes control.
Hypersensitivity: Severe hypersensitivity or anaphylactic reactions have been reported.
5. Adverse Reactions and Clinical Research
Common Adverse Reactions: The most frequent adverse reactions include vasodilation (hot flashes), decreased libido, sweating, headache, anxiety, depression, injection site reactions, and weight gain.
Clinical Research: Clinical trials have demonstrated that goserelin effectively reduces tumor burden in prostate and breast cancers and alleviates pain and lesion size in endometriosis, with effects being reversible upon discontinuation of the drug.
6. Drug Interactions
QT-Prolonging Drugs: Concomitant use with Class IA antiarrhythmics (e.g., quinidine, procainamide), Class III antiarrhythmics (e.g., amiodarone, sotalol), methadone, moxifloxacin, or antipsychotics may increase the risk of QT prolongation and torsades de pointes.
Corticosteroids: Concomitant use may increase the risk of hyperglycemia and exacerbate bone density loss.
7. Pharmaceutical Information
Composition: The active ingredient is goserelin acetate. The implant is a sterile, white to off-white biodegradable polymer cylinder containing 3.6 mg of goserelin.
Appearance: It is supplied as a pre-filled single-dose syringe with a protective guard tube.
Storage: Store at or below 25°C. Use immediately after opening the package.