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What is Zoladex®(goserelin acetate implant)?

Zoladex is a type of hormone therapy called a gonadotropin releasing hormone agonist. Zoladex is used to treat advanced breast cancer in both pre- and perimenopausal women that is hormone receptor positive. It is also used to treat certain forms of prostate cancer and endometriosis. Zoladex is an implant that is injected under the skin and slowly dissolves, releasing its medicine between doses.1

Zoladex is manufactured by TerSera Therapeutics.

What is the ingredient in Zoladex?

The active ingredient in Zoladex is goserelin, a gonadotropin releasing hormone agonist.1

How does Zoladex work?

Many breast cancers are classified as hormone receptor positive (HR+), meaning they have receptors on the surface of their cells where hormones like estrogen can attach. When the hormones connect with these receptors, they can fuel the growth of the cancer cells and lead to them growing and spreading.

Zoladex blocks the release of gonadotropin, a hormone secreted by the pituitary gland that stimulates the ovaries to produce estrogen. By interrupting this hormone process, the patient’s body produces less estrogen. The lack of estrogen interferes with the cancer cell’s growth.1,2

What are some of the possible side effects with Zoladex?

The most common side effects experienced by women with breast cancer who received Zoladex included1,3:

Zoladex may cause a temporary worsening of symptoms of breast cancer, including bone pain, during the first few weeks of treatment.3

Zoladex should cause menstruation to stop in women. If periods continue, patients should report this to their doctor.3

Zoladex may cause injury to the injection site. Any of the following symptoms should be immediately reported to a doctor: abdominal pain, bloating of the abdomen, shortness of breath, dizziness, lightheadedness, and/or signs of confusion.3

Things to know about Zoladex

Zoladex should not be used in women who have an allergy to the medication.3

Zoladex should not be used in women who are pregnant, are planning to become pregnant or are breastfeeding. Zoladex may cause harm to an unborn child. Women who can become pregnant should use effective contraception during Zoladex treatment and for at least 12 weeks after treatment is completed. Patients should discuss effective contraception methods with their doctor.1,3

Before starting treatment with Zoladex, patients should talk to their doctor about all medications (prescription and over-the-counter), vitamins, and herbal supplements they are taking. Some medications or supplements may interfere with each other and may cause side effects.

Dosing information

For the treatment of advanced breast cancer, a 3.6 mg implant of Zoladex is injected under the skin (subcutaneously) in the upper abdomen every 28 days. The implant slowly dissolves over 4 weeks, releasing the active ingredient goserelin.1,4

For more information, read the full prescribing information for Zoladex.

Patients should talk to their doctor if they have any questions, or if they have questions regarding their Zoladex regimen.

  1. Zoladex prescribing information. Available at Accessed 10/1/18.
  2. Zoladex. Chemocare. Available at Accessed 10/1/18.
  3. Zoladex product website. Available at Accessed 10/1/18.
  4. Goserelin (Rx). Medscape. Available at Accessed 10/1/18.