GLYBURIDE: 2,143 Adverse Event Reports & Safety Profile

DESCRIPTION Glyburide and Metformin Hydrochloride Tablets, USP contain 2 oral antihyperglycemic drugs used in the management of type 2 diabetes, glyburide, USP and metformin hydrochloride, USP. Glyburide, USP is an oral antihyperglycemic drug of the sulfonylurea class. The chemical name for glyburide is 1-[[ p -[2-(5-chloro- o -anisamido)ethyl]phenyl]sulfonyl]-3-cyclo-hexylurea. Glyburide, USP is a white or almost white, crystalline powder with a molecular formula of C 23 H 28 ClN 3 O 5 S and a molecular weight of 494. The glyburide used in glyburide and metformin hydrochloride tablets, USP has a particle size at least 20% are less than 2 micron, at least 80% are less than 10 micron and 100% are less than 40 micron. The structural formula is represented below. Metformin hydrochloride, USP is an oral antihyperglycemic drug used in the management of type 2 diabetes. Metformin hydrochloride ( N , N -dimethylimidodicarbonimidic diamide monohydrochloride) is not chemically or pharmacologically related to sulfonylureas, thiazolidinediones, or α-glucosidase inhibitors. It is a white crystals with a molecular formula of C 4 H 12 ClN 5 (monohydrochloride) and a molecular weight of 165.62. Metformin hydrochloride, USP is freely soluble in water, slightly soluble in ethanol (95%), practically insoluble in acetone and in methylene chloride. The structural formula is as shown: Each glyburide and metformin hydrochloride tablet, USP intended for oral administration contains 1.25 mg glyburide USP with 250 mg metformin hydrochloride USP, 2.5 mg glyburide USP with 500 mg metformin hydrochloride USP and 5 mg glyburide USP with 500 mg metformin hydrochloride USP. In addition, each tablet contains the following inactive ingredients: calcium carbonate, croscarmellose sodium, magnesium stearate, microcrystalline cellulose and povidone. Additionally, 1.25 mg/250 mg tablets contain opadry II white 33F28398 which contains hypromellose, lactose monohydrate, polyethylene glycol, talc and titanium dioxide. Additionally, 2.5 mg/500 mg tablets contain opadry II orange 31F530003 which contains FD&C blue #2 aluminum lake, FD&C yellow #5 aluminum lake, FD&C yellow #6 aluminum lake, hypromellose, lactose monohydrate, polyethylene glycol and titanium dioxide. Additionally, 5 mg/500 mg tablets contain opadry II green 31F510000 which contains iron oxide black, iron oxide red, iron oxide yellow, hypromellose, lactose monohydrate, polyethylene glycol and titanium dioxide. figure figure

AND USAGE Glyburide and metformin hydrochloride tablets is indicated as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus. Glyburide and metformin hydrochloride tablets are a combination of glyburide, a sulfonylurea, and metformin hydrochloride (HCl), a biguanide, indicated as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus. ( 1 )

DOSAGE AND ADMINISTRATION General Considerations Dosage of glyburide and metformin hydrochloride tablets must be individualized on the basis of both effectiveness and tolerance while not exceeding the maximum recommended daily dose of 20 mg glyburide/2000 mg metformin. Glyburide and metformin hydrochloride tablets should be given with meals and should be initiated at a low dose, with gradual dose escalation as described below, in order to avoid hypoglycemia (largely due to glyburide), reduce GI side effects (largely due to metformin), and permit determination of the minimum effective dose for adequate control of blood glucose for the individual patient. With initial treatment and during dose titration, appropriate blood glucose monitoring should be used to determine the therapeutic response to glyburide and metformin hydrochloride tablets and to identify the minimum effective dose for the patient. Thereafter, HbA 1c should be measured at intervals of approximately 3 months to assess the effectiveness of therapy. The therapeutic goal in all patients with type 2 diabetes is to decrease FPG, PPG, and HbA 1c to normal or as near normal as possible. Ideally, the response to therapy should be evaluated using HbA 1c (glycosylated hemoglobin), which is a better indicator of long-term glycemic control than FPG alone. No studies have been performed specifically examining the safety and efficacy of switching to glyburide and metformin hydrochloride tablets therapy in patients taking concomitant glyburide (or other sulfonylurea) plus metformin. Changes in glycemic control may occur in such patients, with either hyperglycemia or hypoglycemia possible. Any change in therapy of type 2 diabetes should be undertaken with care and appropriate monitoring.

In

Patients with Inadequate Glycemic Control on Diet and Exercise Recommended starting dose: 1.25 mg glyburide and 250 mg metformin hydrochloride once or twice daily with meals. For patients with type 2 diabetes whose hyperglycemia cannot be satisfactorily managed with diet and exercise alone, the recommended starting dose is 1.25 mg glyburide and 250 mg metformin hydrochloride once a day with a meal. As initial therapy in patients with baseline HbA 1c >9% or an FPG >200 mg/dL, a starting dose of 1.25 mg glyburide and 250 mg metformin hydrochloride twice daily with the morning and evening meals may be used. Dosage increases should be made in increments of 1.25 mg glyburide and 250 mg metformin hydrochloride per day every 2 weeks up to the minimum effective dose necessary to achieve adequate control of blood glucose. In clinical trials of glyburide and metformin hydrochloride tablets as initial therapy, there was no experience with total daily doses >10 mg/2000 mg per day. Glyburide and metformin hydrochloride tablets 5 mg/500 mg should not be used as initial therapy due to an increased risk of hypoglycemia. Glyburide and Metformin Hydrochloride Tablets Use in Patients with Inadequate Glycemic Control on a Sulfonylurea and/or Metformin Recommended starting dose: 2.5 mg/500 mg or 5 mg/500 mg twice daily with meals. For patients not adequately controlled on either glyburide (or another sulfonylurea) or metformin alone, the recommended starting dose of glyburide and metformin hydrochloride tablets is 2.5 mg/500 mg or 5 mg/500 mg twice daily with the morning and evening meals. In order to avoid hypoglycemia, the starting dose of glyburide and metformin hydrochloride tablets should not exceed the daily doses of glyburide or metformin already being taken. The daily dose should be titrated in increments of no more than 5 mg/500 mg up to the minimum effective dose to achieve adequate control of blood glucose or to a maximum dose of 20 mg/2000 mg per day. For patients previously treated with combination therapy of glyburide (or another sulfonylurea) plus metformin, if switched to glyburide and metformin hydrochloride tablets, the starting dose should not exceed the daily dose of glyburide (or equivalent dose of another sulfonylurea) and metformin already being taken. Patients should be monitored closely for signs and symptoms of hypoglycemia following such a switch and the dose of glyburide and metformin hydrochloride tablets should be titrated as described above to achieve adequate control of blood glucose. Addition of Thiazolidinediones to Glyburide and Metformin Hydrochloride Tablets Therapy For patients not adequately controlled on glyburide and metformin hydrochloride tablets, a thiazolidinedione can be added to glyburide and metformin hydrochloride tablets therapy. When a thiazolidinedione is added to glyburide and metformin hydrochloride tablets therapy, the current dose of glyburide and metformin hydrochloride tablets can be continued and the thiazolidinedione initiated at its recommended starting dose. For patients needing additional glycemic control, the dose of the thiazolidinedione can be increased based on its recommended titration schedule. The increased glycemic control attainable with glyburide and metformin hydrochloride tablets plus a thiazolidinedione may increase the potential for hypoglycemia at any time of day. In patients who develop hypoglycemia when receiving glyburide and metformin hydrochloride tablets and a thiazolidinedione, consideration should be given to reducing the dose of the glyburide component of glyburide and metformin hydrochloride tablets. As clinically warranted, adjustment of the dosages of the other components of the antidiabetic regimen should also be considered.

Patients Receiving Colesevelam

When colesevelam is coadministered with glyburide, maximum plasma concentration and total exposure to glyburide is reduced. Therefore, glyburide and metformin hydrochloride tablets should be administered at least 4 hours prior to colesevelam. Recommendations for Use in Renal Impairment Assess renal function prior to initiation of glyburide and metformin hydrochloride tablets and periodically thereafter. Glyburide and metformin hydrochloride tablets are contraindicated in patients with an estimated glomerular filtration rate (eGFR) below 30 mL/minute/1.73 m 2 . Initiation of glyburide and metformin hydrochloride tablets in patients with an eGFR between 30 to 45 mL/minute/1.73 m 2 is not recommended. In patients taking glyburide and metformin hydrochloride tablets whose eGFR later falls below 45 mL/min/1.73 m 2 , assess the benefit risk of continuing therapy. Discontinue glyburide and metformin hydrochloride tablets if the patient’s eGFR later falls below 30 mL/minute/1.73 m 2 (see WARNINGS and PRECAUTIONS ). Discontinuation for Iodinated Contrast Imaging Procedures Discontinue glyburide and metformin hydrochloride tablets 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 m 2 ; in patients with a history of liver disease, alcoholism or heart failure; or in patients who will be administered intra-arterial iodinated contrast. Re-evaluate eGFR 48 hours after the imaging procedure; restart glyburide and metformin hydrochloride tablets if renal function is stable.

Specific Patient Populations

Glyburide and metformin hydrochloride tablets are not recommended for use during pregnancy. The initial and maintenance dosing of glyburide and metformin hydrochloride tablets should be conservative in patients with advanced age, due to the potential for decreased renal function in this population. Any dosage adjustment requires a careful assessment of renal function.

CONTRAINDICATIONS Glyburide tablets are contraindicated in patients with: 1. Known hypersensitivity or allergy to the drug. 2. Diabetic ketoacidosis, with or without coma. This condition should be treated with insulin. 3. Type I diabetes mellitus. 4. Concomitant administration of bosentan.

Special Warning On Increased Risk Of Cardiovascular Mortality

The administration of oral hypoglycemic drugs has been reported to be associated with increased cardiovascular mortality as compared to treatment with diet alone or diet plus insulin. This warning is based on the study conducted by the University Group Diabetes Program (UGDP), a long-term prospective clinical trial designed to evaluate the effectiveness of glucose-lowering drugs in preventing or delaying vascular complications in patients with non-insulin-dependent diabetes. The study involved 823 patients who were randomly assigned to one of four treatment groups. UGDP reported that patients treated for 5 to 8 years with diet plus a fixed dose of tolbutamide (1.5 grams per day) had a rate of cardiovascular mortality approximately 2½ times that of patients treated with diet alone. A significant increase in total mortality was not observed, but the use of tolbutamide was discontinued based on the increase in cardiovascular mortality, thus limiting the opportunity for the study to show an increase in overall mortality. Despite controversy regarding the interpretation of these results, the findings of the UGDP study provide an adequate basis for this warning. The patient should be informed of the potential risks and advantages of glyburide tablets and of alternative modes of therapy. Although only one drug in the sulfonylurea class (tolbutamide) was included in this study, it is prudent from a safety standpoint to consider that this warning may also apply to other oral hypoglycemic drugs in this class, in view of their close similarities in mode of action and chemical structure .

ADVERSE REACTIONS Glyburide and Metformin Hydrochloride In double-blind clinical trials involving glyburide and metformin hydrochloride as initial therapy or as second-line therapy, a total of 642 patients received glyburide and metformin hydrochloride, 312 received metformin therapy, 324 received glyburide therapy, and 161 received placebo. The percent of patients reporting events and types of adverse events reported in clinical trials of glyburide and metformin hydrochloride (all strengths) as initial therapy and second-line therapy are listed in Table 6 .

Table

6: Most Common Clinical Adverse Events (>5%) in Double-Blind Clinical Studies of Glyburide and Metformin Hydrochloride Used as Initial or Second-Line Therapy Adverse Event Number (%) of Patients Placebo N=161 Glyburide N=324 Metformin N=312 Glyburide and Metformin Hydrochloride N=642 Upper respiratory infection 22 (13.7) 57 (17.6) 51 (16.3) 111 (17.3)

Diarrhea

9 (5.6) 20 (6.2) 64 (20.5) 109 (17)

Headache

17 (10.6) 37 (11.4) 29 (9.3) 57 (8.9) Nausea/vomiting 10 (6.2) 17 (5.2) 38 (12.2) 49 (7.6) Abdominal pain 6 (3.7) 10 (3.1) 25 (8) 44 (6.9)

Dizziness

7 (4.3) 18 (5.6) 12 (3.8) 35 (5.5) In a controlled clinical trial of rosiglitazone versus placebo in patients treated with glyburide and metformin hydrochloride (n=365), 181 patients received glyburide and metformin hydrochloride with rosiglitazone and 184 received glyburide and metformin hydrochloride with placebo. Edema was reported in 7.7% (14/181) of patients treated with rosiglitazone compared to 2.2% (4/184) of patients treated with placebo. A mean weight gain of 3 kg was observed in rosiglitazone-treated patients. Disulfiram-like reactions have very rarely been reported in patients treated with glyburide tablets. Hypoglycemia In controlled clinical trials of glyburide and metformin hydrochloride there were no hypoglycemic episodes requiring medical intervention and/or pharmacologic therapy; all events were managed by the patients. The incidence of reported symptoms of hypoglycemia (such as dizziness, shakiness, sweating, and hunger), in the initial therapy trial of glyburide and metformin hydrochloride are summarized in Table 7 . The frequency of hypoglycemic symptoms in patients treated with glyburide and metformin hydrochloride 1.25 mg/250 mg was highest in patients with a baseline HbA 1c <7%, lower in those with a baseline HbA 1c of between 7% and 8%, and was comparable to placebo and metformin in those with a baseline HbA 1c >8%. For patients with a baseline HbA 1c between 8% and 11% treated with glyburide and metformin hydrochloride 2.5 mg/500 mg as initial therapy, the frequency of hypoglycemic symptoms was 30% to 35%. As second-line therapy in patients inadequately controlled on sulfonylurea alone, approximately 6.8% of all patients treated with glyburide and metformin hydrochloride experienced hypoglycemic symptoms. When rosiglitazone was added to glyburide and metformin hydrochloride therapy, 22% of patients reported 1 or more fingerstick glucose measurements ≤50 mg/dL compared to 3.3% of placebo-treated patients. All hypoglycemic events were managed by the patients and only 1 patient discontinued for hypoglycemia. (See PRECAUTIONS: General: Addition of Thiazolidinediones to Glyburide and Metformin Hydrochloride Therapy . )

Gastrointestinal Reactions

The incidence of gastrointestinal (GI) side effects (diarrhea, nausea/vomiting, and abdominal pain) in the initial therapy trial are summarized in Table 7 . Across all glyburide and metformin hydrochloride trials, GI symptoms were the most common adverse events with glyburide and metformin hydrochloride and were more frequent at higher dose levels. In controlled trials, <2% of patients discontinued glyburide and metformin hydrochloride therapy due to GI adverse events.

Table

7: Treatment Emergent Symptoms of Hypoglycemia or Gastrointestinal Adverse Events in a Placebo- and Active-Controlled Trial of Glyburide and Metformin Hydrochloride as Initial Therapy Variable Placebo N=161 Glyburide Tablets N=160 Metformin Tablets N=159 Glyburide and Metformin Hydrochloride 1.25 mg/250 mg Tablets N=158 Glyburide and Metformin Hydrochloride 2.5 mg/500 mg Tablets N=162 Mean Final Dose 0 mg 5.3 mg 1317 mg 2.78 mg/557 mg 4.1 mg/824 mg Number (%) of patients with symptoms of hypoglycemia 5 (3.1) 34 (21.3) 5 (3.1) 18 (11.4) 61 (37.7) Number (%) of patients with gastrointestinal adverse events 39 (24.2) 38 (23.8) 69 (43.3) 50 (31.6) 62 (38.3)

Metformin Hydrochloride

Cholestatic, hepatocellular, and mixed hepatocellular liver injury have been reported with postmarketing use of metformin.

Glyburide Gastrointestinal Reactions

Cholestatic jaundice and hepatitis may occur rarely which may progress to liver failure; the drug should be discontinued if this occurs. Liver function abnormalities, including isolated transaminase elevations, have been reported.

Dermatologic Reactions

Allergic skin reactions, e.g., pruritus, erythema, urticaria, and morbilliform or maculopapular eruptions, occur in 1.5% of glyburide-treated patients. These may be transient and may disappear despite continued use; if skin reactions persist, the drug should be discontinued.

Postmarketing Adverse Reactions

The following adverse reactions have been identified during post-approval use. Because these reactions are reported voluntarily from a population of uncertain size, it is generally not possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Allergic: Angioedema, arthralgia, myalgia, and vasculitis have been reported. Dermatologic: Porphyria cutanea tarda and photosensitivity reactions have been reported with sulfonylureas. Hematologic: Leukopenia, agranulocytosis, thrombocytopenia, which occasionally may present as purpura, hemolytic anemia, aplastic anemia, and pancytopenia, have been reported with sulfonylureas. Metabolic: Hepatic porphyria reactions have been reported with sulfonylureas; however, these have not been reported with glyburide. Disulfiram-like reactions have been reported very rarely with glyburide. Cases of hyponatremia have been reported with glyburide and all other sulfonylureas, most often in patients who are on other medications or have medical conditions known to cause hyponatremia or increase release of antidiuretic hormone.

Other

Reactions: Changes in accommodation and/or blurred vision have been reported with glyburide and other sulfonylureas. These are thought to be related to fluctuation in glucose levels.

AND PRECAUTIONS

• Lactic Acidosis: See boxed warning. ( 5.1 )
• Hypoglycemia: May be severe. Ensure proper patient selection, dosing, and instructions, particularly in at-risk populations (e.g., elderly, renally impaired) and when used with other anti-diabetic medications. ( 5.2 )
• Potential Increased Risk of Cardiovascular Mortality with Sulfonylureas: Inform patient of risks, benefits and treatment alternatives. ( 5.3 )
• Hemolytic anemia: Can occur if glucose 6-phosphate dehydrogenase (G6PD) deficient. Consider a non-sulfonylurea alternative. ( 5.4 )
• Vitamin B 12 Deficiency: Metformin may lower vitamin B 12 levels.
• Measure hematological parameters annually and vitamin B 12 at 2 to 3 year intervals and manage any abnormalities. ( Error! Hyperlink reference not valid. )

5.1 Lactic Acidosis There have been postmarketing 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 (&gt;5 mmol/L), anion gap acidosis (without evidence of ketonuria or ketonemia), and an increased lactate: pyruvate ratio; metformin plasma levels were generally &gt;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 glyburide and metformin hydrochloride.

In

Glyburide and metformin hydrochloride treated patients with a diagnosis or strong suspicion of lactic acidosis, prompt hemodialysis is recommended to correct the acidosis and remove accumulated metformin (metformin HCl 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 Glyburide and metformin hydrochloride 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 Impairment —The 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 ( 2.1 ), Clinical Pharmacology ( 12.3 ) ]: o Before initiating glyburide and metformin hydrochloride, obtain an estimated glomerular filtration rate (eGFR). o Glyburide and metformin hydrochloride is contraindicated in patients with an eGFR less than 30 mL/min/1.73 m 2 [ see Contraindications ( ) ]. o Initiation of glyburide and metformin hydrochloride is not recommended in patients with eGFR between 30 to 45 mL/min/1.73 m 2 . o Obtain an eGFR at least annually in all patient taking glyburide and metformin hydrochloride. In patients at risk for the development of renal impairment (e.g., the elderly), renal function should be assessed more frequently. o In patients taking glyburide and metformin hydrochloride whose eGFR falls below 45 mL/min/1.73 m 2 , assess the benefit and risk of continuing therapy.
• Drug interactions —The concomitant use of glyburide and metformin hydrochloride 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 [ see Drug Interactions ( ) ]. Consider more frequent monitoring of patients.
• Age 65 or Greater —The 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 contrast —Administration 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 glyburide and metformin hydrochloride 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 m 2 ; 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 glyburide and metformin hydrochloride if renal function is stable.
• Surgery and other procedures —Withholding of food and fluids during surgical or other procedures may increase the risk for volume depletion, hypotension, and renal impairment. Glyburide and metformin hydrochloride should be temporarily discontinued while patients have restricted food and fluid intake.
• Hypoxic states —Several 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 glyburide and metformin hydrochloride.
• Excessive Alcohol intake —Alcohol potentiates the effect of metformin on lactate metabolism. Patients should be warned against excessive alcohol intake, acute or chronic, while receiving glyburide and metformin hydrochloride.
• Hepatic impairment —Patients 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 glyburide and metformin hydrochloride in patients with clinical or laboratory evidence of hepatic disease.

5.2 Hypoglycemia All sulfonylurea drugs, including glyburide and metformin hydrochloride, are capable of producing severe hypoglycemia [ see Adverse Reactions ( ) ]. Concomitant use of glyburide and metformin hydrochloride with other antidiabetic medication can increase the risk of hypoglycemia. A lower dose of glyburide and metformin hydrochloride may be required to minimize the risk of hypoglycemia when combining it with other antidiabetic medications. Educate patients to recognize and manage hypoglycemia. When initiating and increasing glyburide and metformin hydrochloride in patients who may be predisposed to hypoglycemia (e.g., the elderly, patients with renal impairment, patients on other anti-diabetic medications) start with a lower dose. Debilitated or malnourished patients, and those with adrenal, pituitary, or hepatic impairment are particularly susceptible to the hypoglycemic action of anti-diabetic medications. Hypoglycemia is also more likely to occur when caloric intake is deficient, after severe or prolonged exercise, or when alcohol is ingested. The patient&apos;s ability to concentrate and react may be impaired as a result of hypoglycemia. Early warning symptoms of hypoglycemia may be different or less pronounced in patients with autonomic neuropathy, the elderly, and in patients who are taking beta-adrenergic blocking medications or other sympatholytic agents. These situations may result in severe hypoglycemia before the patient is aware of the hypoglycemia. These impairments may present a risk in situations where these abilities are especially important, such as driving or operating other machinery. Severe hypoglycemia can lead to unconsciousness or convulsions and may result in temporary or permanent impairment of brain function or death.

5.3 Cardiovascular Mortality The administration of oral hypoglycemic drugs has been reported to be associated with increased cardiovascular mortality as compared to treatment with diet alone or diet plus insulin. This warning is based on the study conducted by the University Group Diabetes Program (UGDP), a long-term prospective clinical study designed to evaluate the effectiveness of glucose-lowering drugs in preventing or delaying vascular complications in patients with type 2 diabetes mellitus. The study involved 823 patients who were randomly assigned to 1 of 4 treatment groups. UGDP reported that patients treated for 5 to 8 years with diet plus a fixed dose of tolbutamide (1.5 grams per day) had a rate of cardiovascular mortality approximately 2½ times that of patients treated with diet alone. A significant increase in total mortality was not observed, but the use of tolbutamide was discontinued based on the increase in cardiovascular mortality, thus limiting the opportunity for the study to show an increase in overall mortality. Despite controversy regarding the interpretation of these results, the findings of the UGDP study provide an adequate basis for this warning. The patient should be informed of the potential risks and benefits of glyburide and of alternative modes of therapy. Although only one drug in the sulfonylurea class (tolbutamide) was included in this study, it is prudent from a safety standpoint to consider that this warning may also apply to other hypoglycemic drugs in this class, in view of their close similarities in mode of action and chemical structure.

5.4 Hemolytic Anemia Treatment of patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency with sulfonylurea agents, including glyburide and metformin hydrochloride, can lead to hemolytic anemia. Avoid use of glyburide and metformin hydrochloride in patients with G6PD deficiency. In postmarketing reports, hemolytic anemia has also been reported in patients who did not have known G6PD deficiency.

5.5 Vitamin B 12 Deficiency In clinical studies of 29-week duration with metformin HCl tablets, a decrease to subnormal levels of previously normal serum vitamin B 12 levels, was observed in approximately 7% of patients. Such decrease, possibly due to interference with B 12 absorption from the B 12 -intrinsic factor complex, may be associated with anemia but appears to be rapidly reversible with discontinuation of metformin or vitamin B 12 supplementation. Certain individuals (those with inadequate vitamin B 12 or calcium intake or absorption) appear to be predisposed to developing subnormal vitamin B 12 levels. Measure hematologic parameters on an annual basis and vitamin B 12 at 2 to 3 year intervals in patients on glyburide and metformin hydrochloride and manage any abnormalities <span class="opacity-50 text-xs">[see Adverse Reactions ( 6.1 ) ]</span>.

5.6 Macrovascular Outcomes There have been no clinical studies establishing conclusive evidence of macrovascular risk reduction with glyburide and metformin hydrochloride.

PRECAUTIONS Glyburide and Metformin Hydrochloride Lactic Acidosis 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 increased 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 glyburide and metformin hydrochloride. In glyburide and metformin hydrochloride 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 glyburide and metformin hydrochloride 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 Impairment - The 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 glyburide and metformin hydrochloride, obtain an estimated glomerular filtration rate (eGFR). Glyburide and metformin hydrochloride is contraindicated in patients with an eGFR less than 30 mL/min/1.73 m 2 (see CONTRAINDICATIONS ). Initiation of glyburide and metformin hydrochloride is not recommended in patients with eGFR between 30 to 45 mL/min/1.73 m 2 . Obtain an eGFR at least annually in all patient taking glyburide and metformin hydrochloride. In patients at risk for the development of renal impairment (e.g., the elderly), renal function should be assessed more frequently. In patients taking glyburide and metformin hydrochloride whose eGFR falls below 45 mL/min/1.73 m 2 , assess the benefit and risk of continuing therapy. Drug interactions - The concomitant use of glyburide and metformin hydrochloride 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 Greater - The 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 contrast - Administration 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 glyburide and metformin hydrochloride 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 m 2 ; 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 glyburide and metformin hydrochloride if renal function is stable. Surgery and other procedures - Withholding of food and fluids during surgical or other procedures may increase the risk for volume depletion, hypotension, and renal impairment. Glyburide and metformin hydrochloride should be temporarily discontinued while patients have restricted food and fluid intake. Hypoxic states - Several 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 glyburide and metformin hydrochloride.

Excessive

Alcohol intake - Alcohol 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 glyburide and metformin hydrochloride. Hepatic impairment - Patients 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 glyburide and metformin hydrochloride in patients with clinical or laboratory evidence of hepatic disease.

Hypoglycemia

Glyburide and metformin hydrochloride 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 glyburide and metformin hydrochloride 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 B 12 levels In controlled clinical trials with metformin of 29 weeks duration, a decrease to subnormal levels of previously normal serum vitamin B 12 , without clinical manifestations, was observed in approximately 7% of patients. Such decrease, possibly due to interference with B 12 absorption from the B 12 -intrinsic factor complex is, however, very rarely associated with anemia and appears to be rapidly reversible with discontinuation of metformin or vitamin B 12 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 B 12 or calcium intake or absorption) appear to be predisposed to developing subnormal vitamin B 12 levels. In these patients, routine serum vitamin B 12 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 glyburide and metformin hydrochloride or any other antidiabetic drug. Addition of Thiazolidinediones to Glyburide and Metformin Hydrochloride Therapy Hypoglycemia Patients receiving glyburide and metformin hydrochloride in combination with a thiazolidinedione may be at risk for hypoglycemia. Weight gain Weight gain was seen with the addition of rosiglitazone to glyburide and metformin hydrochloride, similar to that reported for thiazolidinedione therapy alone. Hepatic effects When a thiazolidinedione is used in combination with glyburide and metformin hydrochloride, periodic monitoring of liver function tests should be performed in compliance with the labeled recommendations for the thiazolidinedione. Information for Patients Glyburide and Metformin Hydrochloride Patients should be informed of the potential risks and benefits of glyburide and metformin hydrochloride 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 glyburide and metformin hydrochloride 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 glyburide and metformin hydrochloride, 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 glyburide and metformin hydrochloride. (See Patient Information printed below.)

Laboratory Tests

Periodic fasting blood glucose (FBG) and HbA 1c 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 B 12 deficiency should be excluded. Instruct patients to inform their doctor that they are taking glyburide and metformin hydrochloride prior to any surgical or radiological procedure, as temporary discontinuation of glyburide and metformin hydrochloride may be required until renal function has been confirmed to be normal (see PRECAUTIONS ).

Drug Interactions

Glyburide and Metformin Hydrochloride 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 glyburide and metformin hydrochloride, the patient should be closely observed for loss of blood glucose control. When such drugs are withdrawn from a patient receiving glyburide and metformin hydrochloride, 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 glyburide and metformin hydrochloride, the patient should be observed closely for hypoglycemia. When such drugs are withdrawn from a patient receiving glyburide and metformin hydrochloride, 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 glyburide and metformin hydrochloride 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 C max of 32% and 47%, respectively. The reductions in glyburide AUC and C max 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 C max by 22% and blood AUC by 15%, without any significant change in metformin renal clearance. When administered with metformin, the C max 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 C max and AUC by 20% and 9%, respectively, and increased the amount excreted in the urine. T max 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 glyburide and metformin hydrochloride 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 glyburide and metformin hydrochloride. Carcinogenesis, Mutagenesis, Impairment of Fertility No animal studies have been conducted with the combined products in glyburide and metformin hydrochloride. 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 glyburide and metformin hydrochloride 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 glyburide and metformin hydrochloride 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 glyburide and metformin hydrochloride based on body surface area comparisons.

Pregnancy Teratogenic Effects Pregnancy

Category B 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, glyburide and metformin hydrochloride should not be used during pregnancy unless clearly needed. (See below.) There are no adequate and well-controlled studies in pregnant women with glyburide and metformin hydrochloride or its individual components. No animal studies have been conducted with the combined products in glyburide and metformin hydrochloride. 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 glyburide and metformin hydrochloride 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 glyburide and metformin hydrochloride 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 to 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 glyburide and metformin hydrochloride be used during pregnancy. However, if it is used, glyburide and metformin hydrochloride 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 glyburide and metformin hydrochloride, taking into account the importance of the drug to the mother. If glyburide and metformin hydrochloride is discontinued, and if diet alone is inadequate for controlling blood glucose, insulin therapy should be considered.

Pediatric Use

The safety and efficacy of glyburide and metformin hydrochloride were evaluated in an active-controlled, double-blind, 26-week randomized trial involving a total of 167 pediatric patients (ranging from 9 to 16 years of age) with type 2 diabetes. Glyburide and metformin hydrochloride was not shown statistically to be superior to either metformin or glyburide with respect to reducing HbA 1c from baseline (see Table 5 ). No unexpected safety findings were associated with glyburide and metformin hydrochloride in this trial.

Table

5: HbA 1c (Percent)

Change From

Baseline at 26 Weeks: Pediatric Study Glyburide 2.5 mg Tablets Metformin 500 mg Tablets Glyburide and Metformin Hydrochloride 1.25 mg/250 mg Tablets Mean Final Dose 6.5 mg 1500 mg 3.1 mg/623 mg Hemoglobin A 1c N=49 N=54 N=57 Baseline Mean (%) 7.7 7.99

7.85 Mean Change from Baseline -0.96 -0.48 -0.8 Difference from Metformin Difference from Glyburide -0.32 +0.16 Geriatric Use Of the 642 patients who received glyburide and metformin hydrochloride in double-blind clinical studies, 23.8% were 65 and older while 2.8% were 75 and older. Of the 1302 patients who received glyburide and metformin hydrochloride 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) .

Drug Interactions 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 glyburide tablets, the patient should be observed closely for hypoglycemia. When such drugs are withdrawn from a patient receiving glyburide tablets, the patient should be observed closely for loss of control. An increased risk of liver enzyme elevations was observed in patients receiving glyburide concomitantly with bosentan. Therefore, concomitant administration of glyburide tablets and bosentan is contraindicated. Certain drugs tend to produce hyperglycemia and may lead to loss of control. These drugs include the 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 glyburide tablets, the patient should be closely observed for loss of control. When such drugs are withdrawn from a patient receiving glyburide tablets, the patient should be observed closely for hypoglycemia. 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. Metformin : In a single-dose interaction study in NIDDM subjects, decreases in glyburide AUC and C max were observed, but were highly variable. The single-dose nature of this study and the lack of correlation between glyburide blood levels and pharmacodynamic effects, makes the clinical significance of this interaction uncertain. Coadministration of glyburide and metformin did not result in any changes in either metformin pharmacokinetics or pharmacodynamics. Colesevelam : Concomitant administration of colesevelam and glyburide resulted in reductions in glyburide AUC and C max of 32% and 47%, respectively. The reductions in glyburide AUC and C max were 20% and 15%, respectively when administered 1 hour before, and not significantly changed (-7% and 4%, respectively) when administered 4 hours before colesevelam. Topiramate : A drug-drug interaction study conducted in patients with type 2 diabetes evaluated the steady-state pharmacokinetics of glyburide (5 mg/day) alone and concomitantly with topiramate (150 mg/day). There was a 22% decrease in C max and a 25% reduction in AUC24 for glyburide during topiramate administration. Systemic exposure (AUC) of the active metabolites, 4-trans-hydroxy-glyburide (M1) and 3-cis hydroxyglyburide (M2), was also reduced by 13% and 15%, and C max was reduced by 18% and 25%, respectively. The steady-state pharmacokinetics of topiramate were unaffected by concomitant administration of glyburide. Carcinogenesis, Mutagenesis, and Impairment of Fertility Studies in rats at doses up to 300 mg/kg/day for 18 months showed no carcinogenic effects. Glyburide is nonmutagenic when studied in the Salmonella microsome test (Ames test) and in the DNA damage/alkaline elution assay. No drug related effects were noted in any of the criteria evaluated in the two year oncogenicity study of glyburide in mice.

Pregnancy Teratogenic

Effects: Pregnancy Category B Reproduction studies have been performed in rats and rabbits at doses up to 500 times the human dose and have revealed no evidence of impaired fertility or harm to the fetus due to glyburide. There are, however, no adequate and well controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed. Because recent information suggests that abnormal blood glucose levels during pregnancy are associated with a higher incidence of congenital abnormalities, many experts recommend that insulin be used during pregnancy to maintain blood glucose as close to normal as possible.

Nonteratogenic

Effects: Prolonged severe hypoglycemia (4 to 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. If glyburide tablets is used during pregnancy, it should be discontinued at least two weeks before the expected delivery date.

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. Because the potential for hypoglycemia in nursing infants may exist, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother. If the drug is discontinued, and if diet alone is inadequate for controlling blood glucose, insulin therapy should be considered.

Pediatric Use

Safety and effectiveness in pediatric patients have not been established.

Geriatric Use

Elderly patients are particularly susceptible to the hypoglycemic action of glucose lowering drugs. Hypoglycemia may be difficult to recognize in the elderly (see PRECAUTIONS ). The initial and maintenance dosing should be conservative to avoid hypoglycemic reactions (see DOSAGE AND ADMINISTRATION ). Elderly patients are prone to develop renal insufficiency, which may put them at risk of hypoglycemia. Dose selection should include assessment of renal function.