What is a Generic Drug?

A generic drug is a copy of the brand-name drug with the same dosage, safety, strength, quality, consumption method, performance, and intended use. Before generics become available on the market, the generic company must prove it has the same active ingredients as the brand-name drug and works in the same way and in the same amount of time in the body.

The only differences between generics and their brand-name counterparts is that generics are less expensive and may look slightly different (eg. different shape or color), as trademarks laws prevent a generic from looking exactly like the brand-name drug.

Generics are less expensive because generic manufacturers don't have to invest large sums of money to develop a drug. When the brand-name patent expires, generic companies can manufacture a copy of the brand-name and sell it at a substantial discount.

Antagon (Ganirelix)

Also Known as Orgalutran


Antagon (Ganirelix)

Prescription Required

0.25mg / 0.5ml

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Generic Equivalent - Antagon (Ganirelix)

Prescription Required


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  • Product Details


    Antagon (Ganirelix) is a gonadotropin-releasing hormone(GnRH) antagonist used to treat infertility in women. Ganirelix works by blocking premature luteinizing hormone (LH) surges that can cause premature ovulation in women undergoing fertility treatment. Ganirelix injection is an injectable medicine used with other hormones to help women undergoing in-vitro fertilization (IVF) or other fertility treatments. 

    Fact Table




    US DailyMed, EU EMA



    Legal status


    Chemical Name


    Elimination half-life

    16.2 hours

    Dosage (Strength)

    0.25mg / 0.5ml


    Consult Doctor



    Protein binding


    PubChem CID



    Not Available


    Not Available

    ATC code






    Routes of administration

    Subcutaneous injection


    Ganirelix is administered subcutaneously (under the skin). The standard dosage is 250 mcg (micrograms) per day during the mid to late part of the follicular phase, following the initiation of FSH treatment on the second or third day of the cycle. 

    Treatment with Ganirelix should be continued until the day of human chorionic gonadotropin (hCG) administration. Antagon should be used with follicle-stimulating hormone (FSH) to prevent premature ovulation in women undergoing assisted reproductive technology (ART). Follow the dosage instructions provided by the healthcare provider and do not exceed the recommended dose.


    Antagon is a synthetic decapeptide that contains ganirelix acetate as its active ingredient.


    Avoid taking or using this medication if any of the following apply:

    • Known or suspected pregnancy
    • Hypersensitivity to Ganirelix or any of its ingredients
    • Hypersensitivity to GnRH or other GnRH analogs


    • Before taking Ganirelix, it is important to inform your doctor about: 
      • If you are allergic to Ganirelix or similar medications
      • About any medications you take, especially if you are taking other hormonal treatments or any medication that may interfere with hormone regulation. 
      • About any medical conditions you have, including blood disorders, liver problems, or kidney problems, as these may affect how Ganirelix works in your body. 
      • If you are pregnant or plan to become pregnant: Ganirelix is used in fertility treatments, so inform your healthcare provider of your pregnancy status or intentions. 
      • If you are breastfeeding or plan to breastfeed: It's unknown if Ganirelix passes into breastmilk. Discuss with your healthcare provider if you intend to breastfeed while on this medication.
    • Ganirelix may cause serious allergic reactions. Seek medical attention immediately if you experience trouble breathing, a rash or hives, or swelling of your face, eyes, lips, tongue, or throat.
    • Ganirelix is administered by injection, and you may experience redness, swelling, or itching at the injection site. Contact your healthcare provider if these symptoms persist or worsen. 
    • Monitor for symptoms of Ovarian Hyperstimulation Syndrome (OHSS), a potentially serious condition. Symptoms may include abdominal pain or bloating, nausea, vomiting, or rapid weight gain. 
    • Certain medications may interact with Ganirelix, altering its effectiveness or causing adverse effects. Inform your healthcare provider about all other medications you are taking. 
    • Regular monitoring by a healthcare provider may be necessary to check hormone levels and ovarian response during treatment with Ganirelix.

    Side Effects

    As with any medication, Ganirelix may have potential side effects that can occur. Some of the most common side effects include:

    • Injection site reactions such as pain, swelling, and redness
    • Headache
    • Nausea
    • Abdominal pain
    • Vaginal bleeding
    • Pelvic pain

    These side effects are usually mild and go away on their own. However, if you experience any of these side effects and they persist or become severe, you should contact your healthcare provider. In addition to these common side effects, there are also some more serious side effects that can occur with the use of Antagon.These may include:

    • Allergic reactions such as hives, rash, itching, difficulty breathing, and swelling of the face, lips, tongue, or throat
    • Ovarian hyperstimulation syndrome (OHSS), which can cause swelling of the ovaries, abdominal pain and bloating, nausea, vomiting, and weight gain

    If you experience any of these serious side effects, you should seek medical attention immediately. These are not all of the possible side effects of Ganirelix. If you have any concerns about the use of this medication, talk to your healthcare provider.


    1. Antagon (Ganirelix) Prescribing Information. Merck & Co., Inc. Accessed August 9, 2023.
    2. Antagon (Ganirelix) Drug Label. West Orange, NJ: Organon, Inc.; 2023.

    IMPORTANT NOTE: The above information is intended to increase awareness of health information and does not suggest treatment or diagnosis. This information is not a substitute for individual medical attention and should not be construed to indicate that use of the drug is safe, appropriate, or effective for you. See your health care professional for medical advice and treatment.

    Product Code : 12159

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