Key takeaways
Zoladex (goserelin) and Firmagon (degarelix) are both used to treat advanced prostate cancer, but they work in different ways. Zoladex is a gonadotropin-releasing hormone (GnRH) agonist, which means it mimics a natural hormone to lower testosterone and estrogen levels. It’s also used to breast breast cancer and endometriosis in females. Firmagon, on the other hand, is a GnRH antagonist that directly blocks the hormone responsible for releasing testosterone. It should only be used in males. Zoladex is available as an implant that is injected under the skin every 4 weeks or every 3 months, while Firmagon is given as 2 injections initially and then 1 injection every 4 weeks. Common side effects for Zoladex include hot flashes and diarrhea, while Firmagon often causes injection site reactions and hot flashes. Both medications are expensive and don’t have generic versions available.
