A kind of fertility drug, GnRH antagonists suppress the production of the hormones LH and FSH. While GnRH agonists lead to an initial surge of the hormones FSH and LH, GnRH antagonists do not create this surge.
Used along with gonadotropins, GnRH antagonists may be part of IVF treatment. They are used to prevent natural ovulation. Instead, the fertility doctor will artificially stimulate ovulation with other fertility drugs, in a controlled manner known as superovulation.
The drug also prevents the natural LH surge, which could lead to the eggs ovulating before they can be retrieved from the ovaries. If the eggs are ovulated before they are retrieved, they get "lost" inside the uterine cavity and cannot be used for IVF treatment.
Anatagon and Cetrotide are GnRH antagonists. They are injectables, meaning they are taken by injection.
Sources:
Medications for Inducing Ovulation: A Guide for Patients. American Society of Reproductive Medicine. Accessed February 3, 2008. http://www.asrm.org/Patients/patientbooklets/ovulation_drugs.pdf
