Although these drugs aren't specifically approved to treat endometriosis, some doctors do prescribe them to treat the disease. GnRH antagonists are the new kids on the block in hormonal medications to treat endometriosis. They seem to have several real benefits, especially with side effects. Two common GnRH antagonists are Cetrorelix acetate (Cetrotide) and Ganirelix acetate (Antagon). They aren't approved yet for endometriosis, and they're very expensive, much more so than agonists (8 to 20 times more expensive!).
GnRH antagonists are very similar to GnRH agonists, but they work much more quickly than agonists. GnRH antagonists are a synthetic peptide that competes with GnRH for its receptor site, just like agonists. Unlike the agonists that initially stimulate the pituitary gland to release its store of FSH and LH, antagonists block the action of the receptor. This blockage of GnRH action results in the pituitary gland decreasing its output of FSH and LH immediately.
GnRH antagonists aren't long-lasting drugs, so they're usually given subcuta-neously, like insulin, through daily injections. One GnRH antagonist, Cetrotide, comes in a higher dose (3 mg) for a once- or twice-a-week dose over eight weeks.
Identifying the side effects to GnRH antagonists
Serum estradiol remains higher with this therapy (around 50 pg/ml), so side effects related to low estrogen are less prevalent. In one study, endometriosis patients undergoing this treatment reported a symptom-free period, with no mood changes, hot flushes, libido loss, vaginal dryness, or other symptoms.
Antagonist side effects aren't as severe as those from agonists. Antagonist effects include
1 Headache 1 Nausea
1 Itching and redness at the injection site
Was this article helpful?