Definition: A GnRH antagonist is a drug that blocks the receptor for gonadotropin-releasing hormone, so LH and FSH release drops without a first rise. Cetrorelix (Cetrotide) and ganirelix are approved to prevent a premature LH surge, which would cause early ovulation, in women having controlled ovarian stimulation for IVF.
Both labels approve them for one purpose: preventing premature LH surges during controlled ovarian stimulation. The ganirelix label says it is used alongside FSH during an IVF or ICSI cycle. Cetrotide is prescribed by doctors experienced in fertility treatment, and pregnancy must be ruled out before starting.
The Cetrotide label says allergic reactions, including some with the first dose, have been reported after approval.
In 949 women, the Cetrotide label lists moderate or severe ovarian hyperstimulation syndrome (3.5%), nausea (1.3%) and headache (1.1%) as the events at 1% or more. There was no placebo group, so these rates cannot be pinned on the drug alone. Injection site redness, bruising, itching and swelling were usually mild. Liver enzyme rises up to three times normal were seen in 1% to 2% of women, and the label says their meaning was not determined. Cetrotide is not intended for people aged 65 and over. IVF cycles involve several drugs on tight timing, so logging each shot with its time is useful.
Read more on Dose Track: Cetrotide side effects · Ganirelix side effects · Cetrotide vs ganirelix