Buserelin is a medication that has been designed to mimic the actions of natural gonadotropin releasing hormone (GnRH or LHRH), a hormone released from the hypothalamus gland in the brain.

The hypothalamus uses GnRH to send messages to the pituitary gland in the brain, which then sends messages to the ovaries in females, and the testicles in males, telling them to produce the sex hormones estrogen (females) and testosterone (males).

Normally, GnRH comes from the hypothalamus in pulses. If GnRH came from the hypothalamus all of the time (rather than in "pulses"), it would have the opposite effect and "turn off" hormone production. Buserelin works by acting in place of GnRH and causes hormone production to be "turned off." As a result, the production of estrogen and testosterone by the body is reduced.

Buserelin is used for the treatment of advanced prostate cancer. It helps prostate cancer by causing a reduction in the amount of testosterone in the blood. It is also used to treat endometriosis (a painful condition caused by growth of extra tissue inside or outside the uterus). It helps endometriosis by reducing the amount of estrogen in the blood.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are using this medication, speak to your doctor. Do not stop using this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to use this medication if their doctor has not prescribed it.

Buserelin is available in injectable forms and nasal solution.

For prostate cancer, the usual starting dose is buserelin 500 µg by subcutaneous (under the skin) injection every 8 hours for 7 days. This is followed by maintenance therapy with an injection of 200 µg buserelin once daily or 400 µg of nasal spray (2 sprays into each nostril) 3 times daily.

Women using buserelin for treatment of endometriosis usually use the buserelin nasal solution at a dose of 400 µg (2 sprays into each nostril) 3 times daily. The treatment usually continues for 6 months but should not continue past 9 months.

If using the injectable form, always use the syringes provided in the kit and dispose of the syringes in a safe manner. Carefully read the patient directions for use available in the package insert. Ask your health care professional if you have any questions. To help reduce redness, itching, or swelling where the medication is injected, rotate the place where you are injecting this medication.

If using the nasal spray, use the spray pump provided. Each spray delivers 100 µg buserelin. Carefully read the patient directions for use available in the package insert. Ask your health professional if you have any questions.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are using the medication without consulting your doctor.

It is important to use this medication exactly as prescribed by your doctor. If you miss a dose, use it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not use a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

For men using buserelin for long-term control of prostate cancer, a long-lasting buserelin implant (called a "depot") can be implanted under the skin into the abdominal wall by the doctor every 2 or 3 months. If you forget to have your implant given on the correct day, have it administered as soon as possible.

Store buserelin at room temperature, away from heat and direct light, and keep it out of the reach of children. The injection can be kept at room temperature for up to 14 days after opening. The nasal spray can be kept at room temperature for up to 5 weeks after opening.

Depot 2 Months
Each applicator contains 1 implant dose consisting of 2 identical cream-coloured, biodegradable, and biocompatible rods. Each implant dose contains a total of 6.6 mg of buserelin acetate, equivalent to 6.3 mg of buserelin base. Nonmedicinal ingredients: poly-(D,L-lactide-co-glycolide). Sterile ready-to-use disposable applicator with an integrated needle (internal needle diameter of 1.4 mm) for s.c. injection.

Depot 3 Months
Each applicator contains 1 implant dose consisting of 3 identical cream-coloured, biodegradable, and biocompatible rods. Each implant dose contains a total of 9.9 mg of buserelin acetate equivalent to 9.45 mg of buserelin base. Nonmedicinal ingredients: poly-(D,L-lactide-co-glycolide). Sterile ready-to-use disposable applicator with an integrated needle (internal needle diameter of 1.4 mm) for s.c. injection.

Do not use this medication if you:

• are allergic to buserelin or any ingredients of this medication
• are a man with non-hormone dependent cancer
• are pregnant or breast-feeding
• have prostate cancer and have had your testicles removed
• have undiagnosed abnormal vaginal bleeding

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is used in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who uses this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people using this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• acne
• breast pain or enlargement
• burning, itching, redness, or swelling at injection site
• change in amount of body hair
• decrease in sexual desire
• dizziness
• headaches
• impotence
• itchiness
• nausea
• nose irritation or dryness (with nasal solution)
• sudden sweating and feeling of warmth (hot flashes)
• trouble sleeping
• vaginal dryness
• weakness
• weight changes (increase or decrease)

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• bone or joint pain
• initial worsening of symptoms or new symptoms such as pain or difficulty urinating
• signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• swelling of the feet or lower legs
• symptoms of irregular heartbeat (e.g., chest pain, dizziness, rapid, pounding heartbeat, shortness of breath)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• symptoms of a severe allergic reaction (e.g., hives; difficulty breathing; difficulty swallowing; or swelling of the face, mouth, tongue, or throat)
• symptoms of severely increased blood pressure: (e.g., chest pain, blurred vision, dizziness, excessive tiredness, headache, stronger or faster heartbeat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Anemia: Reduced testosterone levels contribute to low levels of red blood cells. If you experience symptoms of reduced red blood cell count (anemia) such as shortness of breath, pale skin, or feeling unusually tired, contact your doctor as soon as possible.

Your doctor will do blood tests regularly to monitor the number of specific types of blood cells, including red blood cells, in your blood.

Blood pressure: If you have high blood pressure, this medication may increase your blood pressure. Your blood pressure should be checked regularly while using this medication.

Depression: Changed levels of hormones in the body have been known to cause mood swings and symptoms of depression. If you have depression or a history of depression, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

If you experience symptoms of depression such as poor concentration, changes in weight, changes in sleep, or decreased interest in activities, or notice them in a family member who is taking this medication, contact your doctor as soon as possible.

Diabetes: Buserelin may cause a loss of blood glucose control, and glucose tolerance may change. People with diabetes may find it necessary to monitor their blood sugar more frequently while using this medication.

If you have diabetes or are at risk for developing diabetes, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Disease symptoms: Sometimes when this medication is started, you may experience a temporary worsening of your symptoms that will last usually less than 10 days. If you have prostate cancer, you may also experience new symptoms such as bone pain, tingling or numbness, or blood in the urine, and your doctor may prescribe a medication to help prevent this. If you experience worsening of your symptoms or any new symptoms, contact your doctor.

Dizziness: This medication can cause dizziness. Do not drive or operate machinery until you know this medication does not affect your ability to perform these tasks safely.

Heart problems: This medication may increase the risk of heart problems such as changes in heart rhythm. You may be more at risk of experiencing heart problems if you have congenital long QT syndrome, electrolyte (e.g., potassium) abnormalities, or congestive heart failure, or you are taking medications that affect heart rhythm (e.g., quinidine, procainamide, amiodarone, sotalol, flecainide). Discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Men and the heart: There may be an increased risk of heart-related events (e.g., heart attacks, stroke, heart-related death) in men being treated for prostate cancer with GnRH medications.

Before you start treatment, tell your doctor if you have diabetes or heart disease, have had a previous heart attack or stroke, or have cardiovascular risk factors (e.g., high blood pressure, smoking, or cholesterol). If you have any of these conditions, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Osteoporosis: Buserelin can decrease bone density that can lead to osteoporosis and bone factures. Your doctor will monitor you for this while you are using this medication. If you have osteoporosis or are at risk for it (e.g., have been smoking or drinking excessive amounts of alcohol for a long time, have a family history of osteoporosis, or are taking medications such as prednisone or anti-seizure medications), discuss with your doctor how this medication may affect your medical condition and whether any special monitoring is needed.

Pregnancy: Buserelin should not be used by pregnant women. Use an effective nonhormonal method of birth control (e.g., condom, diaphragm, IUD) while you are using this medication. If you become pregnant while using this medication, stop using the medication and contact your doctor immediately.

Breast-feeding: This medication passes into breast milk. If you are a breast-feeding mother and are taking buserelin, it may affect your baby. Women should not breast-feed while using buserelin.

Children: The safety and effectiveness of using this medication have not been established for children and adolescents less than 18 years of age.

There may be an interaction between buserelin and any of the following:

• amiodarone
• antipsychotics (e.g., chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone, ziprasidone)
• "azole" antifungals (e.g., itraconazole, ketoconazole, posaconazole, voriconazole)
• b2- agonists (e.g., formoterol, salbutamol, salmeterol)
• diabetes medications (e.g., acarbose, canagliflozin, glyburide, insulin, rosiglitazone, sitagliptin)
• disopyramide
• dronedarone
• flecainide
• macrolide antibiotics (e.g., clarithromycin, erythromycin)
• methadone
• procainamide
• quinidine
• quinine
• quinolone antibiotics (e.g., ciprofloxacin, ofloxacin)
• serotonin antagonists (e.g., granisetron, ondansetron)
• sotalol
• tricyclic antidepressants (e.g., amitriptyline, clomipramine, desipramine, trimipramine)
• tyrosine kinase inhibitors (e.g., lapatinib, pazopanib, sunitinib, vandetanib)

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.