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Antagon: An Aid in Artificial Fertilization

Last updated on September 10, 2021

Brand Name: Antagon
Active Ingredient: ganirelix acetate
Indication: aid in artificial fertilization (inhibits premature luteinizing horomone (LH) surges in women undergoing controlled ovarian hyperstimulation)
Company Name: Organon, Inc.


Antagon: An Aid in Artificial FertilizationIn the United States, infertility affects 6.1 percent of American women and their partners. Each year, about 2.7 million couples seek medical help for fertility problems. Latest data released by the American Society for Reproductive Medicine indicated that in 1996 65,800 cycles of assisted reproduction treatment were started.

That same year, 20,000 babies were born with the help of assisted reproductive techniques, of whom 14,054 were born after In Vitro Fertilization (IVF). Antagon reduces total treatment time per IVF cycle from four weeks to about 10 days.

Gonadotriphin releasing hormone (GnRH) is released in the healthy body in pulses and stimulates the synthesis and secretion of LH and follicle-stimulating hormone (FSH). The pulses are observed as rises in serum luteinizing horomone (LH). At midcycle, a substantial increase in GnRH release results in an LH surge. This surge results in the commencement of ovulation, resumption of meiosis in the oocyte, and luteinization.

Assisted reproduction treatment involves the administration of gonadotropins. Antagon (ganirelix acetate) blocks the luteinizing horomone (LH) surge in women undergoing controlled ovarian hyperstimulation (COH). Improperly controlled ovarian hyperstimulation can result in massive ovarian cysts, aseites, pleural effusion, thrombosis, and hypoproteinaemia.

How It Works

Antagon (ganirelix acetate) competitively blocks the GnRH receptors on the pituitary gonadotroph and the subsequent transduction pathway. It induces a rapid, reversible suppression of gonadotropin secretion. Pituitary LH and FSH levels fully recover within 48 hours of discontinuation of Antagon use.

Antagon (ganirelix acetate): Clinical Study Results

antagonTwo clinical studies demonstrated the safety and efficacy of Antagon (ganirelix acetate). Both studies followed similar procedures although they differed in design. On day 2 or 3 of the natural menstrual cycle, the administration of exogenous recombinant FSH 150 IU daily was initiated. Antagon adminstration was begun on the morning of day 7 or 8.

Both drugs were administered until at least 3 follicles were 17 mm or greater in diameter. At that time, human chorionic gonadotrophin (hCG) was administered and Antagon and exogenous recombinant FSH were discontinued. Oocyte retrieval, in vitro fertilization, or intracytoplasmatic sperm injection was then performed.

A multicenter, double-blind, randomized study was conducted to determine the most effective dose of Antagon in the prevention of LH surges in women undergoing COH with recombinant follicle-stimulating hormone (FSH). The highest pregnancy and implantation rates were achieved with the 250 ucg dose of Antagon. A multicenter, randomized, open-label study examined follicular phase treatment with Antagon 250 ucg, using luteal phase GnRH agonist as a reference treatment.

A total of 463 patients were treated with Antagon by subcutaneous injection once daily starting on day 6 of recombinant follicle-stimulating hormone (FSH) treatment. Premature luteinizing horomone (LH) surges occurred in less than 1% of patients prior to hCG administration.

What the Patient Should Know

The following adverse events were reported: gynecological abdominal pain, fetal death, headache, ovarian hyperstimulation syndrome, vaginal bleeding, injection site reaction, nausea, and gastrointestinal abdominal pain. If the patient becomes pregnant, Antagon should be discontinued.

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