Examples

Gonadotropin-releasing hormone (GnRH) agonists and antagonists belong to a group of hormone drugs called GnRH analogues.

Gonadotropin-releasing hormone agonists

Gonadotropin-releasing hormone antagonists

Some GnRH analogues are taken as nasal sprays and some are injected under the skin.

How It Works

Daily GnRH agonist injections overstimulate the pituitary gland, triggering production of more luteinizing hormone (LH) and follicle-stimulating hormone (FSH) than normal, which makes the pituitary gland temporarily shut down. The "disabled" pituitary gland then stops producing LH and FSH, which in turn stops ovulation.

GnRH antagonist injection is a more recent addition to infertility treatment. While agonists act over several days to stop ovulation, antagonists act almost immediately by blocking the effect of GnRH on the pituitary gland. Because an antagonist stops the pituitary from making LH within an hour or two, it doesn't have to be used for as many days as an agonist does.

Why It Is Used

GnRH analogue treatment is used to "shut down" the pituitaryhormones that control the ovaries.

To treat infertility concerns, a GnRH analogue (agonist or antagonist) is used:

• To closely time and control ovulation before an assisted reproductive technology (ART) procedure by shutting down the pituitary gland. This is called "pituitary down-regulation." At the same time or afterward, an ovulation-stimulating medicine is used to trigger ovulation, with the goal of harvesting good-quality eggs on a predictable schedule.
• To closely time ovulation before some insemination procedures, when unpredictable ovulation would make it hard to know when to introduce sperm into a woman's reproductive tract.

How Well It Works

GnRH analogues (agonists and antagonists) predictably stop ovulation and menstruation. Agonists take more days of treatment than antagonists do to shut down the ovaries.

Controlling ovulation timing before an infertility procedure. Shutting down the pituitary with GnRH analogue treatment, paired with a hormone to stimulate egg production, lowers the chance that an ART procedure will be canceled because of early ovulation. For controlling egg production before an infertility treatment, a longer course of GnRH agonist treatment has been shown to produce higher pregnancy and live birth rates, when compared with a short course of doses.¹

Side Effects

All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.

Here are some important things to think about:

• Usually the benefits of the medicine are more important than any minor side effects.
• Side effects may go away after you take the medicine for a while.
• If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.

Callor other emergency services right away if you have:

• Trouble breathing.
• Hives.
• Swelling of your face, lips, tongue, or throat.

Call your doctor if you have:

• A fast or irregular heartbeat.
• Bone, muscle, or joint pain.
• Anxiety, depression, or other mood changes.
• Bleeding between menstrual periods.

Common side effects of this medicine include:

• An irregular menstrual period (or no menstrual period at all).
• Hot flashes.
• Vaginal burning, itching, or dryness.
• Decreased sexual interest.
• Thinning of the bones.
• Increased acne or oily skin or hair.
• An irritated or runny nose (nafarelin only).

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Before insemination, GnRH analogue treatment paired with an ovulation-stimulating treatment increases the risk of conceiving a multiple pregnancy, which can be dangerous for a mother and her fetuses. In the case of an assisted reproductive technology such as in vitro fertilization, this risk is controlled by limiting the number of fertilized eggs that are transferred to the uterus.

Taking medicine

Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.

There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.

Advice for women

After you know you are pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant or trying to get pregnant.

Checkups

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.

References

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