Injectable peptide used in in vitro fertilization to prevent premature ovulation during ovarian stimulation.
Regulatory status
Approved (FDA / EMA)
Family
GnRH antagonist
Scientific evidence
High
Number of findings
1
Where it acts
Sexual and reproductive · Hormones and metabolism
Also known as
ganirelix, Orgalutran, Antagon, Fyremadel
Regulatory status
FDA (US): Approved (1999, Antagon; now ganirelix acetate) to inhibit the premature LH surge in women undergoing controlled ovarian stimulation
EMA (EU): Approved (2000, Orgalutran) to prevent the premature LH surge in controlled ovarian stimulation
Dose
0.25 mg subcutaneously once a day from day 5–6 of FSH stimulation until ovulation induction (FDA/EMA labels).
Safety
Local reactions, headache, nausea; ovarian hyperstimulation syndrome (a risk of stimulation); rare allergic reactions. Contraindicated in pregnancy. Only in fertility treatments under medical supervision.
Differences between women and men
Indication exclusively for women in assisted reproduction treatments. Contraindicated in pregnancy.
Effect by goal · level of evidence
IVF: less ovarian hyperstimulation than agonists
reducesHighmeta-analysis (AAA)in people
−57% hyperstimulation
Cochrane review of 45 trials (7,511 women): GnRH antagonists reduced ovarian hyperstimulation syndrome (OR 0.43) with no clear differences in live births (OR 0.86) versus the long agonist protocol.
It blocks the GnRH receptor in the pituitary and immediately reduces LH and FSH. This prevents the LH surge from triggering ovulation before the needle puncture to retrieve the eggs.
What the evidence says
In people
IVF: less ovarian hyperstimulation than with agonists. Cochrane review of 45 trials (7,511 women): GnRH antagonists reduced ovarian hyperstimulation syndrome (OR 0.43) with no clear difference in live births (OR 0.86) compared with the long agonist protocol. PubMed 21563131