How does this medication work? What will it do for me?

Pegvisomant belongs to the group of medications called growth hormone (GH) antagonists. It is used to treat acromegaly, a condition where the body produces too much growth hormone, and when other treatment have not been effective or cannot be used. It works by blocking the effect of too much growth hormone and improves the symptoms of acromegaly.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are being given 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.

What form(s) does this medication come in?

10 mg
Each single-dose vial of sterile, white lyophilized powder for subcutaneous injection after reconstitution with 1 mL of sterile water for injection, contains pegvisomant protein 10 mg. Nonmedicinal ingredients: glycine, mannitol, sodium phosphate dibasic anhydrous, and sodium phosphate monobasic monohydrate. The stopper in the vial may contain latex.

15 mg
Each single-dose vial of sterile, white lyophilized powder for subcutaneous injection after reconstitution with 1 mL of sterile water for injection, contains pegvisomant protein 15 mg. Nonmedicinal ingredients: glycine, mannitol, sodium phosphate dibasic anhydrous, and sodium phosphate monobasic monohydrate. The stopper in the vial may contain latex.

20 mg
Each single-dose vial of sterile, white lyophilized powder for subcutaneous injection after reconstitution with 1 mL of sterile water for injection, contains pegvisomant protein 20 mg. Nonmedicinal ingredients: glycine, mannitol, sodium phosphate dibasic anhydrous, and sodium phosphate monobasic monohydrate. The stopper in the vial may contain latex.

How should I use this medication?

The first dose of pegvisomant, called a loading dose, is one dose of 40 mg given by subcutaneous (under the skin) injection. The first dose will be given by a health care professional. After this first dose, the recommended dose is 10 mg daily given by injection under the skin of the upper arm, upper thigh, stomach area, or buttocks.

Your doctor may increase or decrease the dose of pegvisomant depending on the results of IGF-I (a type of hormone) levels in your blood. The maximum dose is 30 mg daily. The place of injection should be changed daily to avoid skin problems associated with repeated injection at the same site.

Many things can affect the dose of 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 taking the medication without consulting your doctor.

If you are injecting this medication yourself, your doctor will show you how to use this medication properly. If you are not sure how to use it or have questions about how to use it, contact your doctor. Before using this medication, thoroughly read the patient information provided and ask your doctor if you have any questions. If a caregiver will be giving you the injections, they should be instructed on how to give the injection by your doctor.

The injection must be given within 3 hours of preparing it. The solution for injection should be clear. If it is cloudy, discoloured, or has particles in it, do not use the injection.

It is important to use this medication exactly as prescribed by your doctor. If you miss a dose, skip the missed dose and continue with your regular dosing schedule. Do not administer 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.

Store the powder form of this medication in the refrigerator, do not allow it to freeze, and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not use this medication if you are allergic to pegvisomant or any ingredients of the medication.

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses.

Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes 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 taking 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.

  • chest pain
  • diarrhea
  • dizziness
  • flu-like symptoms (e.g. sudden lack of energy, fever, cough, sore throat)
  • nausea
  • pain
  • pain, redness, swelling at the place of injection
  • sinus infection (pain and congestion)
  • swelling of the hands, feet, or lower legs
  • tingling or burning sensations

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:

  • signs of infection (symptoms may include fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness)
  • symptoms of liver problems (e.g., yellowing of the skin or whites of the eye, dark-coloured urine, unexplained fatigue, nausea, vomiting, or abdominal pain)

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.

Are there any other precautions or warnings for 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.

Diabetes: This medication may lower blood glucose levels. If you have 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.

Latex: The stopper of the vials of this medication may contain latex.

Liver function: This medication may cause an increase in liver function test values and may cause liver problems. Your doctor will monitor your liver function with regular blood tests while you are taking this medication. Using pegvisomant in combination with octreotide (another medication to treat acromegaly) can increase the risk of liver damage due to the medication.

If you experience yellowing of the skin or eyes, abdominal pain, nausea, vomiting, loss of appetite, fatigue, or easy bruising while taking this medication, contact your doctor immediately.

If you have liver disease or decreased liver function, 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.

Tumour growth: This medication may cause tumours that secrete growth hormones to grow. If you have such a tumour, you doctor will monitor you closely while you are using this medication.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if pegvisomant passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children.

Seniors: There is limited information about the safety and effectiveness of using this medication for seniors.

What other drugs could interact with this medication?

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

  • diabetes medication taken by mouth (e.g., acarbose, glyburide, gliclazide, metformin, rosiglitazone, tolbutamide)
  • insulin
  • octreotide and other somatostatin analogues
  • opioid pain medications (e.g., morphine, codeine, oxycodone, tramadol)

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.