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 (Gonal-F, Follistim, Repronex, Bravelle, Menopur) 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 a GnRH agonist and it impedes the production of GnRH at the hypothalamus. Antagon and Cetrotide actually block GnRH at the pituitary producing a “more complete” suppression.
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. "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.
Pregnyl, Ovidrel (recombinant hCG)
hCG products include Profasi, Pregnyl, and Ovidrel (recombinant hCG). Profasi and Pregnyl are derived from the human placenta. Ovidrel is derived from genetic recombinant technology using mammalian cells and is identical to human hCG.
These products are used to trigger ovulation in ART patients and in some stimulated IUI cycles. LH, released by the pituitary, normally triggers ovulation but it is “blocked” in patients receiving either Lupron or Antagon. The body reacts to an hCG spike in the same manner as the LH spike, thus triggering ovulation.
