Short answer: Ganirelix has a half-life of about 12.8 hours (16.2 hours with repeated doses). Levels peak about 1.1 hours after a dose. People vary, so treat these as estimates.
Ganirelix is a GnRH antagonist, a man-made peptide that blocks the GnRH receptor in the pituitary and quickly lowers LH and FSH. It is sold as Ganirelix Acetate Injection (Organon and generic makers) in a ready-to-use syringe, injected under the skin once a day to stop an early LH surge (early ovulation) during IVF.
Also known as: ganirelix acetate.
Ganirelix comes as a single-dose prefilled syringe of 250 mcg in 0.5 mL with a 27 gauge, half-inch needle attached. Nothing is mixed, and the air bubble in the syringe does not need to be removed.
The ganirelix label approves it to prevent early LH surges in women having controlled ovarian stimulation. Label dosing is 250 mcg under the skin once a day in the mid to late follicular phase, after FSH has started on cycle day 2 or 3, continued until the day hCG is given; in the label's studies it started on day 6 of FSH and lasted a mean 5.4 days. The belly around the navel or the upper thigh are named as sites.
The label has no boxed warning. It is not used with allergy to ganirelix or GnRH analogs, or in pregnancy. Allergic reactions, including with the first dose, are the main precaution. In 794 women, gynecological belly pain was 4.8%, headache 3.0% and OHSS 2.4%, counted without regard to cause and with no placebo group. Full numbers are on the ganirelix side effects, ganirelix dosing schedule and ganirelix storage pages, and Cetrotide vs ganirelix compares the two antagonists.
The ganirelix label gives a mean time to peak of 1.1 hours after a 250 mcg injection under the skin, and a half-life of 12.8 hours after one dose and 16.2 hours after repeated daily doses.
Numbers shown are taken from the source above. Half-life varies from person to person.
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