Cetrorelix

Cetrorelix is a synthetic decapeptide GnRH antagonist (Cetrotide) used almost exclusively inside assisted reproduction. During ovarian stimulation a premature LH surge would release the eggs before collection, so the antagonist blocks the pituitary's GnRH receptors for the few days needed.

1. 1

   Competitively blocks pituitary GnRH receptors.

2. 2

   Prevents the mid-cycle LH surge that would trigger ovulation early.

3. 3

   Acts within hours, so it can be started once follicles are large enough.

4. 4

   Suppression lifts quickly when stopped, allowing a planned trigger.

5. 5

   Avoids the initial flare and the long down-regulation of agonist protocols.

• Premature LH surges largely prevented, with continued stimulation until trigger
• Pregnancy rates in antagonist cycles broadly similar to agonist cycles in meta-analyses
• Shorter stimulation duration and fewer injections than long agonist protocols
• Lower risk of ovarian hyperstimulation than agonist protocols

1. 01Al-Inany et al., Gonadotrophin-releasing hormone antagonists for assisted reproductive technology, Cochrane Database of Systematic Reviews 2016
2. 02European Medicines Agency - Cetrotide product information

References link to published literature, regulator pages or literature indexes. Where a link points to a search, it collects the peer-reviewed work on that molecule rather than a single study.