Gonadotropin Releasing Hormone Antagonist
Medication that blocks GnRH receptors to prevent premature luteinizing hormone surge during ovarian stimulation cycles.
Full Definition
Gonadotropin releasing hormone antagonists are synthetic compounds that competitively bind to and block GnRH receptors in the anterior pituitary gland. Unlike GnRH agonists, they provide immediate suppression of gonadotropin release without an initial flare effect. In ART protocols, they are used to prevent premature ovulation during controlled ovarian stimulation. Common examples include cetrorelix and ganirelix, typically administered during the mid-follicular phase when lead follicles reach 14mm in diameter.
Usage
Usage note: Distinguish from GnRH agonists which have opposite initial effects; antagonists provide immediate suppression.
In Context
- "The antagonist protocol using cetrorelix resulted in fewer side effects compared to the long agonist protocol." — Clinical study report
- "GnRH antagonist administration was initiated on stimulation day 6 when the lead follicle measured 14mm." — Treatment protocol documentation