Glucovance

Serious side effects have been reported with Glucovance. See the “Glucovance Precautions” section.

Common side effects of Glucovance include the following:

• stomach pain
• nausea or vomiting
• diarrhea
• dizziness

This is not a complete list of Glucovance side effects. Ask your doctor or pharmacist for more information.

Tell your doctor if you have any side effect that bothers you or that does not go away.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Tell your doctor about all the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements. Especially tell your doctor if you take:

• acetazolamide (Diamox)
• amiloride (Midamor, in Moduretic)
• angiotensin-converting enzyme (ACE) inhibitors such as benazepril (Lotensin), captopril (Capoten), enalapril (Vasotec), fosinopril (Monopril), lisinopril (Prinivil, Zestril), moexipril (Univasc), perindopril (Aceon), quinapril (Accupril), ramipril (Altace), and trandolapril (Mavik)
• anticoagulants ('blood thinners') such as warfarin (Coumadin)
• aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil, Motrin) or naproxen (Aleve, Naprosyn)
• beta-blockers such as atenolol (Tenormin), labetalol (Normodyne), metoprolol (Lopressor, Toprol XL), nadolol (Corgard), and propranolol (Inderal)
• calcium channel blockers such as amlodipine (Norvasc), diltiazem (Cardizem, Dilacor, Tiazac, others), felodipine (Plendil), isradipine (DynaCirc), nicardipine (Cardene), nifedipine (Adalat, Procardia), or verapamil (Calan, Isoptin, Verelan)
• chloramphenicol
• cimetidine (Tagamet)
• clarithromycin (Biaxin)
• cyclosporine (Neoral, Sandimmune)
• digoxin (Lanoxin)
• disopyramide (Norpace)
• diuretics ('water pills')
• fluconazole (Diflucan)
• fluoxetine (Prozac, Sarafem)
• furosemide (Lasix)
• hormone replacement therapy
• insulin or other medications for diabetes
• isoniazid
• MAO inhibitors such as isocarboxazid (Marplan), phenelzine (Nardil), selegiline (Eldepryl, Emsam, Zelaplar), and tranylcypromine (Parnate)
• medications for allergies, asthma, and colds
• medications for mental illness and nausea
• miconazole (Lotrimin, Monistat, others)
• morphine (MS Contin, others)
• niacin
• oral contraceptives (birth control pills)
• oral steroids such as dexamethasone (Decadron, Dexone), methylprednisolone (Medrol), and prednisone (Deltasone)
• phenytoin (Dilantin Phenytek)
• probenecid (Benemid, in Colbenemid)
• procainamide (Procanbid)
• quinidine
• quinine
• quinolone and fluoroquinolone antibiotics such as cinoxacin (Cinobac), ciprofloxacin (Cipro), enoxacin (Penetrex), gatifloxacin (Tequin), levofloxacin (Levaquin), lomefloxacin (Maxaquin), moxifloxacin (Avelox), nalidixic acid (NegGram), norfloxacin (Noroxin), ofloxacin (Floxin), sparfloxacin (Zagam), trovafloxacin and alatrofloxacin combination (Trovan)
• ranitidine (Zantac)
• rifampin
• salicylate pain relievers such as choline magnesium trisalicylate, choline salicylate (Arthropan), diflunisal (Dolobid), magnesium salicylate (Doan's, others), or salsalate (Argesic, Disalcid, Salgesic)
• sulfa antibiotics such as cotrimoxazole (Bactrim, Septra)
• sulfasalazine (Azulfidine)
• thyroid medications
• topiramate (Topamax)
• triamterene (in Dyazide, Maxzide, others)
• trimethoprim (Primsol)
• vancomycin (Vancocin, others)
• zonisamide (Zonegran)

This is not a complete list of Glucovance drug interactions. Ask your doctor or pharmacist for more information.

Before taking Glucovance, tell your doctor about all of your medical conditions. Especially tell your doctor if you:

• are allergic to Glucovance or to any of its ingredients
• have kidney problems, other than diabetes
• have liver problems
• have heart problems
• have a G6PD deficiency
• have hormone disorders or are receiving hormone therapy
• have acute or chronic metabolic acidosis
• are pregnant or breastfeeding

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements.

• Store Glucovance at room temperature away from excess heat, light, and moisture.
• Keep this and all medicines out of the reach of children.
• Avoid unnecessary or prolonged exposure to sunlight and wear protective clothing, sunglasses, and sunscreen. Glucovance may make your skin sensitive to sunlight.

You should not use this medication if you are allergic to glyburide or metformin, or if you have kidney disease or are in a state of diabetic ketoacidosis (call your doctor for treatment with insulin).

If you need to have any type of x-ray or CT scan using a dye that is injected into your veins, you will need to temporarily stop taking glyburide and metformin.

Before you take this medication, tell your doctor if you have liver or heart disease, a history of heart attack or stroke, or an enzyme deficiency called glucose-6-phosphate dehydrogenase deficiency (G6PD).

Some people develop lactic acidosis while taking glyburide and metformin. Get emergency medical help if you have even mild symptoms such as: muscle pain or weakness, numb or cold feeling in your arms and legs, trouble breathing, stomach pain, nausea with vomiting, slow or uneven heart rate, dizziness, or feeling very weak or tired.

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Appropriate studies have not been performed on the relationship of age to the effects of glyburide and metformin combination in the pediatric population. Safety and efficacy have not been established.

Geriatric

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of glyburide and metformin combination in the elderly. However, elderly patients are more likely to have age-related kidney problems which may require caution and an adjustment in the dose for patients receiving glyburide and metformin combination.

Pregnancy

Breast Feeding

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Interactions with Medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

• Acetrizoic Acid
• Bosentan
• Diatrizoate
• Ethiodized Oil
• Iobenzamic Acid
• Iobitridol
• Iocarmic Acid
• Iocetamic Acid
• Iodamide
• Iodipamide
• Iodixanol
• Iodohippuric Acid
• Iodopyracet
• Iodoxamic Acid
• Ioglicic Acid
• Ioglycamic Acid
• Iohexol
• Iomeprol
• Iopamidol
• Iopanoic Acid
• Iopentol
• Iophendylate
• Iopromide
• Iopronic Acid
• Ioseric Acid
• Iosimide
• Iotasul
• Iothalamate
• Iotrolan
• Iotroxic Acid
• Ioxaglate
• Ioxitalamic Acid
• Ipodate
• Metrizamide
• Metrizoic Acid
• Tyropanoate Sodium

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Acarbose
• Aspirin
• Balofloxacin
• Besifloxacin
• Bupropion
• Ciprofloxacin
• Dasabuvir
• Disopyramide
• Dofetilide
• Dolutegravir
• Dulaglutide
• Enoxacin
• Entacapone
• Fleroxacin
• Flumequine
• Gatifloxacin
• Gemifloxacin
• Ioversol
• Lanreotide
• Levofloxacin
• Lixisenatide
• Lomefloxacin
• Metreleptin
• Moxifloxacin
• Nadifloxacin
• Norfloxacin
• Octreotide
• Ofloxacin
• Ombitasvir
• Paritaprevir
• Pasireotide
• Pazufloxacin
• Pefloxacin
• Pioglitazone
• Prulifloxacin
• Ritonavir
• Rufloxacin
• Simeprevir
• Sparfloxacin
• Thioctic Acid
• Tosufloxacin
• Vandetanib

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Acebutolol
• Aminolevulinic Acid
• Atenolol
• Betaxolol
• Bisoprolol
• Bitter Melon
• Carteolol
• Carvedilol
• Celiprolol
• Clarithromycin
• Colesevelam
• Cyclosporine
• Esmolol
• Fenugreek
• Fluvastatin
• Furazolidone
• Gemfibrozil
• Glucomannan
• Guar Gum
• Iproniazid
• Isocarboxazid
• Labetalol
• Levobunolol
• Linezolid
• Methylene Blue
• Metipranolol
• Metoprolol
• Moclobemide
• Nadolol
• Nebivolol
• Nialamide
• Oxprenolol
• Patiromer
• Penbutolol
• Phenelzine
• Pindolol
• Practolol
• Procarbazine
• Propranolol
• Psyllium
• Ranolazine
• Rasagiline
• Rifampin
• Rifapentine
• Safinamide
• Saxagliptin
• Selegiline
• Sotalol
• Timolol
• Tranylcypromine
• Verapamil
• Voriconazole
• Warfarin

Interactions with Food/Tobacco/Alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following is usually not recommended, but may be unavoidable in some cases. If used together, your doctor may change the dose or how often you use this medicine, or give you special instructions about the use of food, alcohol, or tobacco.

• Ethanol

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

• Alcohol intoxication or
• Underactive adrenal glands or
• Underactive pituitary gland or
• Undernourished condition or
• Weakened physical condition or
• Any other condition that causes low blood sugar—Patients with these conditions may be more likely to develop low blood sugar while taking glyburide and metformin combination.

• Blood poisoning or
• Dehydration, severe or
• Heart or blood vessel disorders—Lactic acidosis can occur in these conditions and chances of it occurring are even greater with a medicine that contains metformin.

• Diabetic ketoacidosis (high ketones and acid in the blood) or
• Kidney disease, severe or
• Type I diabetes—Should not be used in patients with these conditions.

• Fever or
• Infection or
• Surgery or
• Trauma—These conditions may cause temporary problems with blood sugar control and your doctor may want to treat you temporarily with insulin.

• Glucose-6-phosphate dehydrogenase (G6PD) deficiency (an enzyme problem)—May cause hemolytic anemia (a blood disorder) in patients with this condition.

• Heart attack, acute or
• Heart disease (eg, congestive heart failure) or
• Vitamin B12 deficiency—Use with caution. May make these conditions worse.

• Kidney disease or
• Liver disease—Use with caution. Effects may be increased because of slower removal of the medicine from the body.

It is very important that your doctor check your progress at regular visits to make sure this medicine is working properly. Blood tests may be needed to check for unwanted effects.

Do not take this medicine together with bosentan (Tracleer®). Also, make sure your doctor knows about all other medicines you are using for diabetes, including insulin.

Under certain conditions, too much metformin can cause lactic acidosis. The symptoms of lactic acidosis are severe and quick to appear. They usually occur when other health problems not related to the medicine are present and very severe, such as a heart attack or kidney failure. The symptoms of lactic acidosis include abdominal or stomach discomfort, decreased appetite, diarrhea, fast, shallow breathing, a general feeling of discomfort, muscle pain or cramping, and unusual sleepiness, tiredness, or weakness. If you have any symptoms of lactic acidosis, get emergency medical help right away.

It is very important to carefully follow any instructions from your health care team about:

• Alcohol—Drinking alcohol may cause severe low blood sugar. Discuss this with your health care team.
• Other medicines—Do not take other medicines unless they have been discussed with your doctor. This especially includes nonprescription medicines such as aspirin, and medicines for appetite control, asthma, colds, cough, hay fever, or sinus problems.
• Counseling—Other family members need to learn how to prevent side effects or help with side effects if they occur. Also, patients with diabetes may need special counseling about diabetes medicine dosing changes that might occur because of lifestyle changes, such as changes in exercise and diet. Furthermore, counseling on contraception and pregnancy may be needed because of the problems that can occur in patients with diabetes during pregnancy.
• Travel—Keep your recent prescription and your medical history with you. Be prepared for an emergency as you would normally. Make allowances for changing time zones and keep your meal times as close as possible to your usual meal times.
• In case of emergency—There may be a time when you need emergency help for a problem caused by your diabetes. You need to be prepared for these emergencies. It is a good idea to wear a medical identification (ID) bracelet or neck chain at all times. Also, carry an ID card in your wallet or purse that says that you have diabetes and a list of all your medicines.

Check with your doctor right away if you start having chest pain or discomfort, nausea, pain or discomfort in the arms, jaw, back, or neck, trouble breathing, sweating, or vomiting while you are using this medicine. These may be symptoms of a serious heart problem, and could be a heart attack.

This medicine may cause hypoglycemia (low blood sugar). This is more common when this medicine is taken together with certain medicines. Low blood sugar must be treated before it causes you to pass out (unconsciousness). People feel different symptoms of low blood sugar. It is important that you learn which symptoms you usually have so you can treat it quickly. Talk to your doctor about the best way to treat low blood sugar.

Hyperglycemia (high blood sugar) may occur if you do not take enough or skip a dose of your medicine, overeat or do not follow your meal plan, have a fever or infection, or do not exercise as much as usual. High blood sugar can be very serious and must be treated right away. It is important that you learn which symptoms you have in order to treat it quickly. Talk to your doctor about the best way to treat high blood sugar.

This medicine may interact with the dye used for an X-ray or CT scan. Your doctor should advise you to stop taking it before you have any medical exams or diagnostic tests that might cause less urine output than usual. You may be advised to start taking the medicine again 48 hours after the exams or tests if your kidney function is tested and found to be normal.

• It is used to lower blood sugar in patients with high blood sugar (diabetes).

• Store at room temperature.
• Store in a dry place. Do not store in a bathroom.
• Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
• Check with your pharmacist about how to throw out unused drugs.

• If your symptoms or health problems do not get better or if they become worse, call your doctor.
• Do not share your drugs with others and do not take anyone else's drugs.
• Keep a list of all your drugs (prescription, natural products, vitamins, OTC) with you. Give this list to your doctor.
• Talk with the doctor before starting any new drug, including prescription or OTC, natural products, or vitamins.
• Some drugs may have another patient information leaflet. Check with your pharmacist. If you have any questions about this medicine, please talk with your doctor, nurse, pharmacist, or other health care provider.
• If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

This information should not be used to decide whether or not to take Glucovance (glyburide and metformin) or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to Glucovance. This information is not specific medical advice and does not replace information you receive from the healthcare provider. You must talk with the healthcare provider for complete information about the risks and benefits of using this medicine.

Review Date: October 4, 2017

Glucovance

There have been post-marketing cases of metformin-associated lactic acidosis, including fatal cases. These cases had a subtle onset and were accompanied by nonspecific symptoms such as malaise, myalgias, abdominal pain, respiratory distress, or increased somnolence; however, hypotension and resistant bradyarrhythmias have occurred with severe acidosis. Metformin-associated lactic acidosis was characterized by elevated blood lactate concentrations (>5 mmol/L), anion gap acidosis (without evidence of ketonuria or ketonemia), and an increases lactate:pyruvate ratio; metformin plasma levels were generally >5 mcg/mL. Metformin decreases liver uptake of lactate increasing lactate blood levels which may increase the risk of lactic acidosis, especially in patients at risk.

If metformin-associated lactic acidosis is suspected, general supportive measures should be instituted promptly in a hospital setting, along with immediate discontinuation of Glucovance. In Glucovance treated patients with a diagnosis or strong suspicion of lactic acidosis, prompt hemodialysis is recommended to correct the acidosis and remove accumulated metformin (metformin hydrochloride is dialyzable with a clearance of up to 170 mL/min under good hemodynamic conditions). Hemodialysis has often resulted in reversal of symptoms and recovery.

Educate patients and their families about the symptoms of lactic acidosis and if these symptoms occur instruct them to discontinue Glucovance and report these symptoms to their healthcare provider.

For each of the known and possible risk factors for metformin-associated lactic acidosis, recommendations to reduce the risk of and manage metformin-associated lactic acidosis are provided below:

•  Renal ImpairmentThe postmarketing metformin-associated lactic acidosis cases primarily occurred in patients with significant renal impairment.

The risk of metformin accumulation and metformin-associated lactic acidosis increases with the severity of renal impairment because metformin is substantially excreted by the kidney. Clinical recommendations based upon the patient’s renal function include

(see DOSAGE AND ADMINISTRATION,CLINICAL PHARMACOLOGY).

•  Before initiating Glucovance, obtain an estimated glomerular filtration rate (eGFR).

•  Glucovance is contraindicated in patients with an eGFR less than 30 mL/min/1.73 m2 (see CONTRAINDICATIONS).

•  Initiation of Glucovance is not recommended in patients with eGFR between 30-45 mL/min/1.73 m2.

•   Obtain an eGFR at least annually in all patient taking Glucovance. In patients at risk for the development of renal impairment (e.g., the elderly), renal function should be assessed more frequently.                                                                                                            

•   In patients taking Glucovance whose eGFR falls below 45 mL/min/1.73 m2, assess the benefit and risk of continuing  therapy.

• Drug interactionsThe concomitant use of Glucovance with specific drugs may increase the risk of metformin-associated lactic acidosis: those that impair renal function, result in significant hemodynamic change, interfere with acid-base balance, or increase metformin accumulation. Consider more frequent monitoring of patients.                                                                                               
• Age 65 or GreaterThe risk of metformin-associated lactic acidosis increases with the patient’s age because elderly patients have a greater likelihood of having hepatic, renal, or cardiac impairment than younger patients. Assess renal function more frequently in elderly patients
• Radiologic studies with contrastAdministration of intravascular iodinated contrast agents in metformin-treated patients has led to an acute decrease in renal function and the occurrence of lactic acidosis. Stop Glucovance at the time of, or prior to, an iodinated contrast imaging procedure in patients with an eGFR between 30 and 60 mL/min/1.73 m2; in patients with a history of hepatic impairment, alcoholism or heart failure, or in patients who will be administered intra-arterial iodinated contrast. Reevaluate eGFR 48 hours after the imaging procedure, and restart Glucovance if renal function is stable.
• Surgery and other proceduresWithholding of food and fluids during surgical or other procedures may increase the risk for volume depletion, hypotension, and renal impairment. Glucovance should be temporarily discontinued while patients have restricted food and fluid intake.
• Hypoxic statesSeveral of the postmarketing cases of metformin-associated lactic acidosis occurred in the setting of acute congestive heart failure (particularly when accompanied by hypoperfusion and hypoxemia). Cardiovascular collapse (shock), acute myocardial infarction, sepsis, and other conditions associated with hypoxemia have been associated with lactic acidosis and may cause prerenal azotemia. When such an event occurs, discontinue Glucovance.
• Excessive Alcohol intakeAlcohol is known to potentiate the effect of metformin on lactate metabolism. Patients, therefore, should be warned against excessive alcohol intake, acute or chronic, while receiving Glucovance.
• Hepatic impairmentPatients with hepatic impairment have developed cases of metformin-associated lactic acidosis. This may be due to impaired lactate clearance resulting in higher lactate blood levels. Therefore, avoid use of Glucovance in patients with clinical or laboratory evidence of hepatic disease.

Hypoglycemia

Glucovance is capable of producing hypoglycemia or hypoglycemic symptoms, therefore, proper patient selection, dosing, and instructions are important to avoid potential hypoglycemic episodes. The risk of hypoglycemia is increased when caloric intake is deficient, when strenuous exercise is not compensated by caloric supplementation, or during concomitant use with other glucose-lowering agents or ethanol. Renal or hepatic insufficiency may cause elevated drug levels of both glyburide and metformin hydrochloride, and the hepatic insufficiency may also diminish gluconeogenic capacity, both of which increase the risk of hypoglycemic reactions. Elderly, debilitated, or malnourished patients and those with adrenal or pituitary insufficiency or alcohol intoxication are particularly susceptible to hypoglycemic effects. Hypoglycemia may be difficult to recognize in the elderly and people who are taking beta-adrenergic blocking drugs.

Glyburide

Hemolytic anemia

Treatment of patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency with sulfonylurea agents can lead to hemolytic anemia. Because Glucovance belongs to the class of sulfonylurea agents, caution should be used in patients with G6PD deficiency and a non-sulfonylurea alternative should be considered. In postmarketing reports, hemolytic anemia has also been reported in patients who did not have known G6PD deficiency.

Metformin Hydrochloride

Vitamin B12 levels

In controlled clinical trials with metformin of 29 weeks duration, a decrease to subnormal levels of previously normal serum vitamin B12, without clinical manifestations, was observed in approximately 7% of patients. Such decrease, possibly due to interference with B12 absorption from the B12-intrinsic factor complex is, however, very rarely associated with anemia and appears to be rapidly reversible with discontinuation of metformin or vitamin B12 supplementation. Measurement of hematologic parameters on an annual basis is advised in patients on metformin and any apparent abnormalities should be appropriately investigated and managed (see PRECAUTIONS:Laboratory Tests).

Certain individuals (those with inadequate vitamin B12 or calcium intake or absorption) appear to be predisposed to developing subnormal vitamin B12 levels. In these patients, routine serum vitamin B12 measurements at 2- to 3-year intervals may be useful.

Macrovascular Outcomes

There have been no clinical studies establishing conclusive evidence of macrovascular risk reduction with Glucovance or any other antidiabetic drug.

Hypoglycemia

Patients receiving Glucovance in combination with a thiazolidinedione may be at risk for hypoglycemia.

Weight gain

Weight gain was seen with the addition of rosiglitazone to Glucovance, similar to that reported for thiazolidinedione therapy alone.

Hepatic effects

When a thiazolidinedione is used in combination with Glucovance, periodic monitoring of liver function tests should be performed in compliance with the labeled recommendations for the thiazolidinedione.

Information for Patients

Glucovance

Patients should be informed of the potential risks and benefits of Glucovance and alternative modes of therapy. They should also be informed about the importance of adherence to dietary instructions; a regular exercise program; and regular testing of blood glucose, glycosylated hemoglobin, renal function, and hematologic parameters.

The risks of lactic acidosis associated with metformin therapy, its symptoms, and conditions that predispose to its development, as noted in the WARNINGS and PRECAUTIONS sections, should be explained to patients. Patients should be advised to discontinue Glucovance immediately and promptly notify their health practitioner if unexplained hyperventilation, myalgia, malaise, unusual somnolence, or other nonspecific symptoms occur. Once a patient is stabilized on any dose level of Glucovance, gastrointestinal symptoms, which are common during initiation of metformin therapy, are unlikely to be drug related. Later occurrence of gastrointestinal symptoms could be due to lactic acidosis or other serious disease.

The risks of hypoglycemia, its symptoms and treatment, and conditions that predispose to its development should be explained to patients and responsible family members.

Patients should be counseled against excessive alcohol intake, either acute or chronic, while receiving Glucovance. (See Patient Information printed below.)

Laboratory Tests

Periodic fasting blood glucose (FBG) and HbA1c measurements should be performed to monitor therapeutic response.

Initial and periodic monitoring of hematologic parameters (e.g., hemoglobin/hematocrit and red blood cell indices) and renal function (serum creatinine) should be performed, at least on an annual basis. While megaloblastic anemia has rarely been seen with metformin therapy, if this is suspected, vitamin B12 deficiency should be excluded.

Instruct patients to inform their doctor that they are taking Glucovance prior to any surgical or radiological procedure, as temporary discontinuation of Glucovance may be required until renal function has been confirmed to be normal (see PRECAUTIONS).

Drug Interactions

Glucovance

Certain drugs tend to produce hyperglycemia and may lead to loss of blood glucose control. These drugs include thiazides and other diuretics, corticosteroids, phenothiazines, thyroid products, estrogens, oral contraceptives, phenytoin, nicotinic acid, sympathomimetics, calcium channel blocking drugs, and isoniazid. When such drugs are administered to a patient receiving Glucovance, the patient should be closely observed for loss of blood glucose control. When such drugs are withdrawn from a patient receiving Glucovance, the patient should be observed closely for hypoglycemia. Metformin is negligibly bound to plasma proteins and is, therefore, less likely to interact with highly protein-bound drugs such as salicylates, sulfonamides, chloramphenicol, and probenecid as compared to sulfonylureas, which are extensively bound to serum proteins.

Glyburide

The hypoglycemic action of sulfonylureas may be potentiated by certain drugs, including nonsteroidal anti-inflammatory agents and other drugs that are highly protein bound, salicylates, sulfonamides, chloramphenicol, probenecid, coumarins, monoamine oxidase inhibitors, and beta-adrenergic blocking agents. When such drugs are administered to a patient receiving Glucovance, the patient should be observed closely for hypoglycemia. When such drugs are withdrawn from a patient receiving Glucovance, the patient should be observed closely for loss of blood glucose control.

An increased risk of liver enzyme elevations was observed in patients receiving glyburide concomitantly with bosentan. Therefore concomitant administration of Glucovance and bosentan is contraindicated.

A possible interaction between glyburide and ciprofloxacin, a fluoroquinolone antibiotic, has been reported, resulting in a potentiation of the hypoglycemic action of glyburide. The mechanism for this interaction is not known.

A potential interaction between oral miconazole and oral hypoglycemic agents leading to severe hypoglycemia has been reported. Whether this interaction also occurs with the intravenous, topical, or vaginal preparations of miconazole is not known.

Colesevelam: Concomitant administration of colesevelam and glyburide resulted in reductions in glyburide AUC and Cmax of 32% and 47%, respectively. The reductions in glyburide AUC and Cmax were 20% and 15%, respectively, when administered 1 hour before, and not significantly changed (−7% and 4%, respectively) when administered 4 hours before colesevelam.

Metformin Hydrochloride

Furosemide

A single-dose, metformin-furosemide drug interaction study in healthy subjects demonstrated that pharmacokinetic parameters of both compounds were affected by coadministration. Furosemide increased the metformin plasma and blood Cmax by 22% and blood AUC by 15%, without any significant change in metformin renal clearance. When administered with metformin, the Cmax and AUC of furosemide were 31% and 12% smaller, respectively, than when administered alone, and the terminal half-life was decreased by 32%, without any significant change in furosemide renal clearance. No information is available about the interaction of metformin and furosemide when coadministered chronically.

Nifedipine

A single-dose, metformin-nifedipine drug interaction study in normal healthy volunteers demonstrated that coadministration of nifedipine increased plasma metformin Cmax and AUC by 20% and 9%, respectively, and increased the amount excreted in the urine. Tmax and half-life were unaffected. Nifedipine appears to enhance the absorption of metformin. Metformin had minimal effects on nifedipine.

Drugs that reduce metformin clearance

Concomitant use of drugs that interfere with common renal tubular transport systems involved in the renal elimination of metformin (e.g., organic cationic transport-2 [OCT2] / multidrug and toxin extrusion [MATE] inhibitors such as ranolazine, vandetanib, dolutegravir, and cimetidine) could increase systemic exposure to metformin and may increase the accumulation of metformin and the risk for lactic acidosis. Consider the benefits and risks of concomitant use. Such interaction between metformin and oral cimetidine has been observed in normal healthy volunteers in both single- and multiple-dose, metformin-cimetidine drug interaction studies, with a 60% increase in peak metformin plasma and whole blood concentrations and a 40% increase in plasma and whole blood metformin AUC. There was no change in elimination half-life in the single-dose study. Metformin had no effect on cimetidine pharmacokinetics.

In healthy volunteers, the pharmacokinetics of metformin and propranolol, and metformin and ibuprofen were not affected when coadministered in single-dose interaction studies.

Metformin is negligibly bound to plasma proteins and is, therefore, less likely to interact with highly protein-bound drugs such as salicylates, sulfonamides, chloramphenicol, and probenecid, as compared to the sulfonylureas, which are extensively bound to serum proteins.

Carbonic Anhydrase Inhibitors

Topiramate or other carbonic anhydrase inhibitors (e.g., zonisamide, acetazolamide or dichlorphenamide) frequently causes a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. Concomitant use of these drugs with Glucovance may increase the risk for lactic acidosis. Consider more frequent monitoring of these patients.

Alcohol

Alcohol is known to potentiate the effects of metformin on lactate metabolism. Warn patients against excessive alcohol intake while receiving Glucovance.

Carcinogenesis, Mutagenesis, Impairment of Fertility

No animal studies have been conducted with the combined products in Glucovance. The following data are based on findings in studies performed with the individual products.

Glyburide

Studies in rats with glyburide alone at doses up to 300 mg/kg/day (approximately 145 times the maximum recommended human daily [MRHD] dose of 20 mg for the glyburide component of Glucovance based on body surface area comparisons) for 18 months revealed no carcinogenic effects. In a 2-year oncogenicity study of glyburide in mice, there was no evidence of treatment-related tumors.

There was no evidence of mutagenic potential of glyburide alone in the following in vitro tests: Salmonella microsome test (Ames test) and in the DNA damage/alkaline elution assay.

Metformin Hydrochloride

Long-term carcinogenicity studies were performed with metformin alone in rats (dosing duration of 104 weeks) and mice (dosing duration of 91 weeks) at doses up to and including 900 mg/kg/day and 1500 mg/kg/day, respectively. These doses are both approximately 4 times the MRHD dose of 2000 mg of the metformin component of Glucovance based on body surface area comparisons. No evidence of carcinogenicity with metformin alone was found in either male or female mice. Similarly, there was no tumorigenic potential observed with metformin alone in male rats. There was, however, an increased incidence of benign stromal uterine polyps in female rats treated with 900 mg/kg/day of metformin alone.

There was no evidence of a mutagenic potential of metformin alone in the following in vitro tests: Ames test (S. typhimurium), gene mutation test (mouse lymphoma cells), or chromosomal aberrations test (human lymphocytes). Results in the in vivo mouse micronucleus test were also negative.

Fertility of male or female rats was unaffected by metformin alone when administered at doses as high as 600 mg/kg/day, which is approximately 3 times the MRHD dose of the metformin component of Glucovance based on body surface area comparisons.

Pregnancy

Recent information strongly suggests that abnormal blood glucose levels during pregnancy are associated with a higher incidence of congenital abnormalities. Most experts recommend that insulin be used during pregnancy to maintain blood glucose as close to normal as possible. Because animal reproduction studies are not always predictive of human response, Glucovance should not be used during pregnancy unless clearly needed. (See below.)

There are no adequate and well-controlled studies in pregnant women with Glucovance or its individual components. No animal studies have been conducted with the combined products in Glucovance. The following data are based on findings in studies performed with the individual products.

Glyburide

Reproduction studies were performed in rats and rabbits at doses up to 500 times the MRHD dose of 20 mg of the glyburide component of Glucovance based on body surface area comparisons and revealed no evidence of impaired fertility or harm to the fetus due to glyburide.

Metformin Hydrochloride

Metformin alone was not teratogenic in rats or rabbits at doses up to 600 mg/kg/day. This represents an exposure of about 2 and 6 times the MRHD dose of 2000 mg of the metformin component of Glucovance based on body surface area comparisons for rats and rabbits, respectively. Determination of fetal concentrations demonstrated a partial placental barrier to metformin.

Nonteratogenic Effects

Prolonged severe hypoglycemia (4-10 days) has been reported in neonates born to mothers who were receiving a sulfonylurea drug at the time of delivery. This has been reported more frequently with the use of agents with prolonged half-lives. It is not recommended that Glucovance be used during pregnancy. However, if it is used, Glucovance should be discontinued at least 2 weeks before the expected delivery date. (See Pregnancy: Teratogenic Effects: Pregnancy Category B.)

Nursing Mothers

Although it is not known whether glyburide is excreted in human milk, some sulfonylurea drugs are known to be excreted in human milk. Studies in lactating rats show that metformin is excreted into milk and reaches levels comparable to those in plasma. Similar studies have not been conducted in nursing mothers. Because the potential for hypoglycemia in nursing infants may exist, a decision should be made whether to discontinue nursing or to discontinue Glucovance, taking into account the importance of the drug to the mother. If Glucovance is discontinued, and if diet alone is inadequate for controlling blood glucose, insulin therapy should be considered.

Pediatric Use

The safety and efficacy of Glucovance were evaluated in an active-controlled, double-blind, 26-week randomized trial involving a total of 167 pediatric patients (ranging from 9-16 years of age) with type 2 diabetes. Glucovance was not shown statistically to be superior to either metformin or glyburide with respect to reducing HbA1c from baseline (see Table 5). No unexpected safety findings were associated with Glucovance in this trial.

Geriatric Use

Of the 642 patients who received Glucovance in double-blind clinical studies, 23.8% were 65 and older while 2.8% were 75 and older. Of the 1302 patients who received Glucovance in open-label clinical studies, 20.7% were 65 and older while 2.5% were 75 and older. No overall differences in effectiveness or safety were observed between these patients and younger patients, and other reported clinical experience has not identified differences in response between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.

In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy and the higher risk of lactic acidosis. Assess renal function more frequently in elderly patients (see also WARNINGS, PRECAUTIONS, and DOSAGE AND ADMINISTRATION).