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

This combination product contains 2 medications (rosiglitazone and metformin) that work together to control blood glucose (blood sugar) levels for people with type 2 diabetes. It is used for people who cannot take other oral (taken by mouth) diabetes medications, or whose blood sugar is not well controlled by any other oral diabetes medications.

Rosiglitazone belongs to the class of medications called thiazolidinediones. Rosiglitazone reduces blood glucose levels by helping insulin to work more effectively and allowing the cells of the body to take in glucose more easily. Metformin belongs to the class of medications called biguanides. Metformin works by reducing the amount of glucose made by the liver and by making it easier for glucose to enter the tissues of the body.

Oral diabetes medications are used to lower blood glucose when diet, exercise, and weight reduction have not lowered blood glucose levels enough on their own. Lowering and controlling blood glucose levels may help prevent or delay complications of diabetes such as heart disease, kidney disease, or blindness. This combination medication starts to work within 1 or 2 weeks, but the full effects may not be seen for 2 to 3 months.

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 taking this medication, speak to your doctor. Do not stop taking 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 take this medication if their doctor has not prescribed it.

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What form(s) does this medication come in?

Rosiglitazone - metformin is no longer being manufactured for sale in Canada and is no longer available under any brand names. This article is being kept available for reference purposes only. If you are using this medication, speak with your doctor or pharmacist for information about your treatment options.

How should I use this medication?

The dose of rosiglitazone and metformin will vary according each person's needs and response to the medication. It should be taken twice daily with food. The maximum daily dose is 8 mg of rosiglitazone and 2,000 mg of metformin (i.e., 2 tablets twice daily of the 2 mg/500 mg strength).

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 taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take 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 take 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.

It is important to follow your doctor's instructions regarding blood glucose monitoring to ensure that you get the maximum benefit from the medication. It is also very important to closely follow diet and exercise plans as discussed with your health professionals while you are taking medication for lowering blood glucose.

Store this medication at room temperature, protect it from light and moisture, 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 take rosiglitazone - metformin if you:

  • are allergic to rosiglitazone, metformin, or any ingredients of the medication
  • are pregnant or breastfeeding
  • have a history of lactic acidosis
  • have a serious infection, trauma, or had recent surgery
  • have acute or chronic metabolic acidosis, including diabetic ketoacidosis
  • have cardiovascular collapse (shock) or conditions associated with lower oxygen levels in the blood, such as certain heart and lung problems
  • have excessive alcohol intake (either in the short or long term)
  • have heart failure
  • have kidney disease or poor kidney function
  • are severely dehydrated
  • have severely reduced liver function
  • have type 1 diabetes

Note: Use of rosiglitazone - metformin should be temporarily stopped (starting 48 hours before the test) by people undergoing tests requiring intravenous injection of contrast materials that contain iodine.

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.

  • constipation
  • diarrhea
  • nausea
  • stomach pain
  • unpleasant or metallic taste in the mouth
  • vomiting
  • weight gain

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

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

  • muscle tenderness or weakness
  • signs of anemia (low red blood cell count; e.g., feeling very weak or tired, or having a fast heartbeat)
  • signs of fluid retention (e.g., swelling of the arms, legs, hands, or feet; or a rapid increase in weight)
  • signs of liver problems (e.g., nausea, vomiting, stomach pain, loss of appetite, tiredness, dark urine, or yellowing of the skin)
  • signs of low blood sugar (e.g., dizziness, lack of energy, drowsiness, headache, trembling or shakiness, sweating, or hunger)
  • unexpected vaginal bleeding or spotting while using oral contraceptives
  • vision changes

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

  • chest pain
  • signs of a heart attack (e.g., sudden pain or discomfort in the chest, neck, jaw, shoulder, arms, or back; shortness of breath; nausea or indigestion; sweating or cool clammy skin; and fear, anxiety, or denial)
  • signs of a severe allergic reaction (e.g., hives; shortness of breath; or swelling of the face, throat, tongue, or mouth)
  • signs of fluid accumulation in the lungs (e.g., severe shortness of breath that worsens when lying down)
  • signs of fluid or swelling in the back of the eye (e.g., blurred vision or decreased vision)
  • signs of heart failure (e.g., shortness of breath [especially at night], getting tired easily, or swollen ankles or feet)
  • signs of lactic acidosis (a buildup of lactic acid in the blood; e.g., feeling very weak or tired, unusual muscle pain, unusual fatigue or drowsiness, trouble breathing, unusual nausea or vomiting, feeling dizzy or lightheaded, or slow or irregular 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.

Are any nutrients depleted by this medication?

Some medications can affect vitamin and nutrient levels in the body. Below is a list of nutrient depletions associated with this medication. Talk to your doctor or pharmacist about whether taking a supplement is recommended or if you have any questions or concerns.

Avandamet may deplete vitamin B12

How can this nutrient deficiency affect me?
Vitamin B12, also known as cyancobalamin or cobalamin, is involved in the body's metabolism, DNA synthesis, and the maturation of red blood cells. It also helps maintain the nervous system. Vitamin B12 deficiency is most common in people on meatless diets since it is not found in grains, fruits, or vegetables.

What can I do about this?
Talk to your pharmacist about vitamin B12 deficiency. Vitamin B12 is available in supplement form. Before starting any nutrient supplement, always talk with your pharmacist first.

Are there any other precautions or warnings for this medication?

Before you begin taking 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 take this medication.

Fluid retention and heart failure: Rosiglitazone can cause fluid buildup in the body, which may lead to heart failure. Your doctor will monitor you for these problems. If you develop fluid buildup or swelling, shortness of breath, fatigue, or excessive weight gain while taking this medication, contact your doctor immediately. If you have a history of heart failure, you should not take rosiglitazone. Since the risk of heart failure and fluid buildup increases when rosiglitazone is used with other antidiabetes medications, rosiglitazone - metformin should not be used by people who are also taking a sulfonylurea (e.g., glyburide, gliclazide) or insulin.

Fractures: Women taking rosiglitazone may be at an increased risk of bone fractures, especially of the upper arm, hand, and foot. Discuss the risk and benefits of using this medication with your doctor.

Heart attack and chest pain: Rosiglitazone can increase the risk of chest pain (angina) and heart attacks. If you have underlying heart disease, or are at a high risk of heart attack, discuss the risks and benefits of using this medication with your doctor. This medication is not recommended for people who take nitrates (e.g., nitroglycerin, isosorbide mononitrate, isosorbide dinitrate), which are used to relieve chest pain.

Kidney function: Kidney disease or reduced kidney function may cause this medication to build up in the body, causing side effects. If you have reduced kidney function or kidney disease, 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.

Lactic acidosis: Lactic acidosis is a rare but serious problem that occurs when the body doesn’t get rid of metformin fast enough. It mostly occurs in people who have impaired kidney function. Excessive alcohol intake can also increase the risk of lactic acidosis. When it does occur (very rarely), it is fatal in 50% of cases. If you notice symptoms of lactic acidosis (including diarrhea, unusual nausea or vomiting, fast shallow breathing, muscle pain or cramping, unusual sleepiness, unusual tiredness or weakness, feeling cold, dizziness or lightheaded, slow or irregular heartbeat), get emergency medical attention immediately.

Liver: Rosiglitazone may cause liver damage which in some cases, has caused death. If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Loss of blood glucose control: Loss of blood glucose control can occur during times of acute stress such as fever, trauma, infection, or surgery. During these times, your doctor may temporarily stop this medication and use insulin until you have recovered.

Ovulation: Some women using rosiglitazone may start having menstrual periods, even after not having a period due to a medical condition (e.g., polycystic ovary syndrome). As a result, there may be a risk that you could get pregnant if adequate contraception is not used. Talk to your doctor about the need for birth control.

Surgery: This medication should be stopped 2 days before any surgical procedure (except minor procedures with no restrictions on food or fluid intake).

Vision: Rosiglitazone may cause swelling of the retina in the eye. If you experience any vision changes while taking rosiglitazone, contact your doctor immediately.

Vitamin B12 and folic acid: Some people may not be able to absorb enough vitamin B12 and folic acid while they are taking this medication. People using this medication should have their levels of vitamin B12 and folic acid checked at least every 1 to 2 years.

Pregnancy: This medication should not be used during pregnancy. Usually, insulin is used to control high blood glucose during pregnancy. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if rosiglitazone and metformin pass 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 this medication have not been established for children under 18 years of age.

Seniors: Seniors may be more at risk for serious side effects from this medication due to age-related changes in kidney function. Lower doses of this medication may be needed.

What other drugs could interact with this medication?

There may be an interaction between rosiglitazone – metformin and any of the following:

  • acetazolamide
  • alcohol
  • American ginseng
  • amiodarone
  • angiotensin converting enzyme inhibitors (ACEIs; captopril, enalapril, ramipril)
  • angiotensin receptor blockers (ARBs; e.g., candasartan, irbesartan, losartan)
  • barbiturates (e.g., butalbital, pentobarbital, phenobarbital)
  • birth control pills
  • buserelin
  • calcium channel blocking medications (e.g., nifedipine, verapamil)
  • carbamazepine
  • celecoxib
  • cephalexin
  • cimetidine
  • cholestyramine
  • colestipol
  • inhaled corticosteroids (e.g., budesonide, ciclesonide, fluticasone)
  • oral corticosteroids (e.g., dexamethasone, hydrocortisone, prednisone)
  • dabrafenib
  • deferasirox
  • digoxin
  • diuretics (water pills; e.g., furosemide, hydrochlorothiazide, triamterene)
  • dofetilide
  • eltrombopag
  • enzalutamide
  • estrogens (e.g., ethinyl estradiol, conjugated estrogens, estrogens plus progestogen)
  • garlic
  • gemfibrozil
  • glycopyrrolate
  • goserelin
  • iodinated contrast material
  • lamotrigine
  • lapatinib
  • leuprolide
  • isoniazid
  • methotrexate
  • mifepristone
  • monoamine oxidase inhibitors (MAOIs; e.g., moclobemide, phenelzine, rasagiline, selegiline, tranylcypromine)
  • morphine
  • mycophenolate
  • nilotinib
  • nitrates (e.g., nitroglycerin, isosorbide mononitrate, isosorbide dinitrate)
  • octreotide
  • other antidiabetes medications (e.g., glyburide, insulin, pioglitazone, repaglinide)
  • paclitaxel
  • pegvisomant
  • phenothiazines (e.g., chlorpromazine, thioridazine, prochlorperazine)
  • phenytoin
  • pregabalin
  • primidone
  • quinidine
  • quinine
  • rabeprazole
  • ranitidine
  • rifampin
  • ritonavir
  • selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, duloxetine, fluoxetine, paroxetine, sertraline)
  • somatropin
  • stiripentol
  • sympathomimetics (e.g., epinephrine, pseudoephedrine)
  • tamoxifen
  • topiramate
  • tretinoin
  • trimethoprim
  • zopiclone

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.

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