Ganirelix acetate (or diacetate), sold under the brand names Orgalutran and Antagon among others, is an injectable competitive gonadotropin-releasing hormone antagonist (GnRH antagonist). It is primarily used in assisted reproduction to control ovulation. The drug works by blocking the action of GnRH upon the pituitary, thus rapidly suppressing the production and action of LH and FSH. Ganirelix is used in fertility treatment to prevent premature ovulation that could result in the harvesting of eggs that are too immature to be used in procedures such as in vitro fertilization.
GnRH agonists are also sometimes used in reproductive therapy, as well as to treat disorders involving sex-steroid hormones, such as endometriosis.One advantage of using GnRH antagonists is that repeated administration of GnRH agonists results in decreased levels of gonadotropins and sex steroids due to desensitization of the pituitary. This is avoided when using GnRH antagonists such as ganirelix.The success of ganirelix in reproductive therapy has been shown to be comparable to that when using GnRH agonists.
Ganirelix is used as a fertility treatment drug for women and/or people with ovaries. Spécifiquement, it is used to prevent premature ovulation in people with ovaries undergoing fertility treatment involving ovarian hyperstimulation that causes the ovaries to produce multiple eggs. When such premature ovulation occurs, the eggs released by the ovaries may be too immature to be used in in-vitro fertilisation. Ganirelix prevents ovulation until it is triggered by injecting human chorionic gonadotrophin (hCG).
Ganirelix is administered by a subcutaneous injection of 250 µg once per day during the mid to late follicular phase of a patient's menstrual cycle. Treatment should start on the 5th or 6th day after the start of ovarian stimulation, and the mean duration for its use is five days. Preferably, the subcutaneous injections are delivered in the upper leg, and the patient can be trained to do this themself. Continued use of the drug should take place until the administration of hCG begins. hCG administration is begun when a sufficient number of follicles have developed due to the effects of endogenous and or exogenously administered follicle stimulating hormone.
