Lupron, (leuprolide acetate), Antagon (ganirelix acetate), Cetrotide (cetrorelix acetate)
These products are given in
IVF cycles because they cause “down regulation” thus lowering levels of
FSH, LH, and estrogen. When one of these products is given, it induces a “menopausal state” and FSH must be given by injection to stimulate follicular recruitment. This process can be thought of as blocking the effect of the body’s hormones and replacing them with controlled injections of FSH and LH or hCG. FSH is given according to patient specific protocols and may begin prior to the stimulation cycle.
Lupron works by first stimulating and then inhibiting the production of gonadotropin releasing hormone (GnRH) at the hypothalamus. Since GnRH is inhibited, it cannot signal the pituitary to produce FSH or LH. Antagon and Cetrotide are GnRH antagonists, which means they reduce GnRH without first stimulating it.
Lupron is also effective in treating
endometriosis because it lowers estrogen levels by blocking FSH and LH. Endometrial tissue is dependent upon estrogen for growth.
Most importantly, ovulation does not occur while taking one of these products, which is why they are used in
IVF. Normally, a surge of LH is released by the pituitary thirty-six hours before ovulation. This surge cannot occur while a patient is on Lupron or Antagon because the pituitary does not receive the appropriate “signal” from the hypothalamus. Early ovulation (prior to IVF egg retrieval) could cause the “loss” of the IVF cycle. Ovulation will only occur after an injection of
hCG or LH is administered. The egg retrieval is scheduled according to when the hCG dose is given.