GnRH Antagonists for In Vitro Fertilization (IVF)

Whether or not you have insurance, fertility treatment can be confusing, emotional, and expensive. You may be prescribed several different types of medications, and they can vary based on the type of treatment you’re receiving.

Gonadotropin-releasing hormone antagonists (GnRH antagonists) are one type of medication used in fertility treatments. Specifically, they’re used as part of an in vitro fertilization (IVF) cycle. Examples of GnRH antagonists include Ganirelix (ganirelix acetate) or Cetrotide (cetrorelix). Let’s take a closer look.

What are GnRH antagonists?

GnRH antagonists are used during an IVF cycle to prevent ovulation. Ovulation occurs when the egg is released from the ovary. Using a GnRH antagonist lets your fertility doctor control egg development and retrieve the eggs at the best time. This helps make sure that your treatment is most likely to work.

GnRH antagonists vs. agonists

GnRH is a hormone that affects the pituitary gland in the brain. GnRH agonists and antagonists are used to stimulate the ovaries so they produce more eggs. They’re both used during IVF, but they work in different ways. 

GnRH agonists, like leuprolide acetate, act just like natural GnRH that the body makes. They tell the pituitary gland to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH). But after a few days, GnRH agonists will stop the pituitary gland from releasing these hormones. As a result, estrogen levels fall so the ovaries don’t release eggs before you have your egg retrieval.

GnRH antagonists, like ganirelix acetate, work by immediately stopping the pituitary from releasing FSH and LH. So GnRH antagonists also keep eggs from being released too early. 

In general, GnRH agonists are helpful when you have low ovarian reserve and are going through IVF. If you’re older, you may need GnRH agonists as part of your treatment plan. GnRH antagonists are more helpful if you have a high ovarian reserve.

How long does an IVF antagonist cycle take?

An antagonist protocol includes 10 days of injections. Of all the different types of IVF protocols, it has the fewest injections over the fewest days — that’s why it’s often called the “short protocol.” But the entire IVF process with an antagonist protocol takes much longer.

At the beginning of the IVF cycle, you may need to take birth control pills for up to 17 days. Then you’ll stop taking the pills for 4 days and have a baseline ultrasound and bloodwork. Depending on the results, your reproductive endocrinologist will ask you to start your stimulation injections. After about 4 to 5 days, you’ll add in your GnRH antagonist injection, which will prevent you from ovulating. 

You’ll need to get your blood work checked every few days to see how you are responding to the injections. You’ll also have an ultrasound to see how your eggs are growing. 

After about 9 to 10 days of injections, you will be ready for a “trigger” shot. This shot will let your eggs mature so you can have an egg retrieval 36 hours later. Keep in mind that some people may need a few more days, depending on how well they respond to the medication. 

What are the side effects of GnRH antagonists?

GnRH antagonist injections commonly cause bruising or redness at the injection site. Other side effects include:

• Itching, redness, and swelling at the site of the injection 

• Nausea

• Headache

• Hot flashes

• Night sweats 

Some people also develop ovarian hyperstimulation syndrome (OHSS). OHSS causes swelling in the body, especially in the ovaries. This can lead to kidney problems and blood clots. 

OHSS is a serious complication, but it’s become less common with newer IVF medications. During your cycle, your reproductive center will make sure you are not developing signs of OHSS. 

How can you save on your prescription?

Like most fertility drugs, GnRH antagonists may not be covered through your insurance. Or you may have a very high copay or coinsurance. Fortunately, there still are a few things you can do to bring down your costs.

GoodRx offers discounts at your regular pharmacy, as well as prices from MDR Pharmaceutical Care, a popular online fertility pharmacy. You can save hundreds over the course of your treatment by shopping around. 

Fertility savings programs can also help you save money on IVF medication costs. Some manufacturers offer coupons. Some fertility centers also offer cost sharing programs that can help lower costs. 

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Written by:

Adriena Beatty D.O., MBA, CPE

Adriena Beatty, DO, MBA, CPE, is an Army veteran and board-certified obstetrician and gynecologist with over 20 years of experience. She is a graduate from Tuskegee University with a degree in chemical engineering and chemistry.

Edited by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

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