Medications used to treat acromegaly
Medications for acromegaly may be used after surgery, particularly when it has not been possible to completely remove the entire pituitary tumour, and growth hormone and insulin-like growth factor 1 (IGF-1) levels remain high or increase again following the operation.
Medications may be used as the main treatment option instead of surgery if the tumour is inaccessible to surgery, you are at high risk of surgical complications or if you decide, after weighing up all your treatment options, that you do not want to have surgery.
What is the aim of medical treatment?
Medical treatment is used to keep growth hormone and IGF-1 levels within the normal range, and to help control the symptoms of acromegaly.
Some medical treatments may also reduce the size of your pituitary tumour.
What medicines are used to treat acromegaly?
There are three groups of medicines used to treat acromegaly: somatostatin analogues, dopamine agonists and a growth hormone receptor antagonist.
Somatostatin analogues are synthetic versions of somatostatin, which reduces the release of growth hormone.
There are three somatostatin analogues available in Canada: octreotide acetate (available as an injectable and an injectable suspension), pasireotide (available as an injectable suspension) and lanreotide (available as an injectable).
The octreotide injectable is given every day as an injection under the skin (subcutaneous injection).
The octreotide injectable suspension is given once every four weeks as an injection into the muscle of the buttocks (deep intragluteal injection).
Pasireotide is given by your doctor or nurse every four weeks as an injection into the muscles of the buttocks (deep intramuscular injection).
Lanreotide is given as an injection under the skin (deep subcutaneous injection) usually once every 28 days, however, this may change depending on how you respond.
Dopamine agonists can also help to reduce the release of growth hormone in the body.
Bromocriptine is a dopamine agonist available in Canada for the treatment of acromegaly. Bromocriptine comes in tablets and capsules, and it is usually taken daily by mouth with food.
Growth hormone receptor antagonist
Pegvisomant is a growth hormone receptor antagonist currently available in Canada. It is given every day as an injection under the skin (subcutaneous injection), and it works by blocking the effect of too much growth hormone.
Are there side effects with these medical treatments?
It is important to read the Consumer Information leaflet when you first start treatment and also from time to time while being treated, to check that you understand how it works and the possible side effects that may occur.
It is also important that you report any side effects you experience to the healthcare professional who prescribed your treatment in case your treatment needs to be revised. He or she may also need to pass on this information to the manufacturer of the medicine and local health authority if necessary.
Below is a list of acromegaly medications and their possible side effects. These are not all the possible side effects you may experience with these medicines.
Side effects of somatostatin analogues
Like all medicines, octreotide may cause some side effects. A few people experience pain at the injection site and sometimes swelling and rash.
Some side effects can be serious
- Gallstones, leading to sudden back pain.
- Too much or too little sugar in the blood.
- Underactive thyroid gland (hypothyroidism) causing changes in heart rate, appetite or weight; tiredness, feeling cold, or swelling at the front of the neck.
- Changes in thyroid function tests.
- Inflammation of the gallbladder (cholecystitis).
- Impaired glucose tolerance.
- Irregular heart beat (slow or fast).
- Thirst, low urine output, dark urine, dry flushed skin.
- Hypersensitivity (allergic) reactions including skin rash.
- A type of an allergic reaction (anaphylaxis) which causes difficulty in swallowing or breathing, rash, hives, swelling of the face, lips, tongue or throat, tingling, possibly with a drop in blood pressure with dizziness or loss of consciousness.
- Acute inflammation of the pancreas gland causing severe stomach pain (pancreatitis).
- Liver inflammation (hepatitis); symptoms may include yellowing of the skin and eyes (jaundice), nausea, vomiting, loss of appetite, generally feeling unwell, itching, light-coloured urine.
- Low level of platelet in blood (thrombocytopenia); increased bleeding or bruising, fatigue, weakness.
Other side effects include:
- stomach pain
- feeling of fullness in the stomach
- flatulence (wind)
- loss of appetite
- stomach discomfort after meal
- fatty stools
- loose stools
- discoloration of faeces
- change in liver function tests
- hair loss
- shortness of breath.
Side effects with lanreotide include the following:
- Flatulence (passing gas)
- Weight loss
- Loss of appetite
- Fatty stools (stools may be bulky and appear pale and oily)
- Swollen tummy
- Eye redness
- Ringing in the ears
- Tiredness or decreased energy
- Hair loss
- Muscle pains or spasms
- Joint, bone or mouth pain
- Weakness, numbness, tingling or pain in the hands or feet
- Swelling in the arms or legs
- Pain during menstruation
- Feeling hot with reddening of the skin
- Excessive sweating
- Night sweats
- Hard swelling of the injection site, and rarely, a persistent hard swelling
Lanreotide can also cause abnormal blood test results. If you are prescribed lanreotide, your doctor will decide when to perform blood tests and other tests like a gallbladder ultrasound.
Very common and common serious side effects of lanreotide include:
- Abdominal pain
- Diarrhea or loose stools
- Formation of gallstones in the gallbladder
- Injection site reaction
- Decreased heart rate
- High blood pressure
- Underactive thyroid gland
- Pancreatitis (inflammation of the pancreas)
- Liver problems
- Diabetes, worsening of diabetes
- Low blood sugar
Side effects may include:
• Nausea, abdominal pain, bloating
• Hair loss
• Headache, dizziness
• Pain, discomfort, itch and swelling at the injection site
If any of these affects you severely, tell your doctor.
Very common and common serious side effects include:
• High level of sugar in the blood
• Low cortisol levels
• Low level of red blood cells
• Slow heart beat
• Prolonged QT interval
• Change in liver function test results
• Change in pancreatic function test results
• Change in blood coagulation parameters
Pasireotide can cause abnormal blood test results. Your doctor will decide when to perform blood tests and will interpret the results.
Side effects of dopamine agonists
The most commonly reported side effects of bromocriptine are:
- Gastrointestinal side effects like abdominal pain, diarrhea and constipation.
Rarely, bromocriptine can also make people feel dizzy or lightheaded, potentially leading to fainting.
Side effects of growth hormone receptor antagonists
The most common side effects related to the use of the drug are pain, infection, reaction at the site of injection, influenza, and nausea.
Mild to serious allergic (anaphylactic) reactions have been reported in some patients taking pegvisomant. Symptoms of a serious allergic reaction may include one or more of the following: swelling of the face, tongue, lips, or throat; wheezing or trouble breathing (spasm of the larynx); generalized skin rash, nettle rash (urticaria) or itching; or dizziness.
A small number of patients who have used pegvisomant have developed liver problems.
Your doctor will draw some of your blood before and during treatment with pegvisomant to check how you are responding to the medicine, to change the dose if necessary, and to check for potential liver problems.
Some patients may develop changes in their blood sugar level.
Some patients may develop skin thickening at the injection site that could lead to lumps (lipohypertrophy).
This is not a complete list of side effects
If you would like more information about the medications used to treat acromegaly, talk to your healthcare professional. They can often provide information booklets that outline the various treatment choices available.
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