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Glyburide and Metformin

Medically reviewed by Drugs.com. Last updated on Aug 7, 2020.

Pronunciation

(GLYE byoor ide & met FOR min)

Index Terms

  • Glyburide and Metformin Hydrochloride
  • Glyburide/Metformin
  • Metformin and Glyburide

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product

Tablet, Oral:

Glucovance: Glyburide 5 mg and metformin hydrochloride 500 mg [DSC], Glyburide 2.5 mg and metformin hydrochloride 500 mg [DSC]

Generic: Glyburide 1.25 mg and metformin hydrochloride 250 mg, Glyburide 2.5 mg and metformin hydrochloride 500 mg, Glyburide 5 mg and metformin hydrochloride 500 mg

Brand Names: U.S.

  • Glucovance [DSC]

Pharmacologic Category

  • Antidiabetic Agent, Biguanide
  • Antidiabetic Agent, Sulfonylurea

Pharmacology

The combination of glyburide and metformin is used to improve glycemic control in patients with type 2 diabetes mellitus by using two different, but complementary, mechanisms of action:

Glyburide: Stimulates insulin release from the pancreatic beta cells; reduces glucose output from the liver; insulin sensitivity is increased at peripheral target sites

Metformin: Decreases hepatic glucose production, decreasing intestinal absorption of glucose and improves insulin sensitivity (increases peripheral glucose uptake and utilization)

Time to Peak

Glucovance: 2.75 hours when taken with food

Use: Labeled Indications

Diabetes mellitus, type 2: As an adjunct to diet and exercise, to improve glycemic control in adults with type 2 diabetes

Contraindications

Hypersensitivity to metformin, glyburide, or any component of the formulation; severe renal impairment (eGFR <30 mL/minute/1.73 m2); acute or chronic metabolic acidosis, including diabetic ketoacidosis, with or without coma; concomitant administration of bosentan

Documentation of allergenic cross-reactivity for sulfonylureas is limited. However, because of similarities in chemical structure and/or pharmacologic actions, the possibility of cross-sensitivity cannot be ruled out with certainty.

Dosing: Adult

Diabetes mellitus, type 2: Oral:

Initial:

Patients with inadequate glycemic control on diet and exercise alone: Glyburide 1.25 mg/metformin 250 mg once or twice daily with meals.

Patients with inadequate glycemic control on metformin or glyburide (or another sulfonylurea) monotherapy: Glyburide 2.5 mg/metformin 500 mg or glyburide 5 mg/metformin 500 mg twice daily with meals.

Patients already receiving a combination of metformin and glyburide (or another sulfonylurea) as individual components: Do not exceed the daily dose of metformin and glyburide (or equivalent dose of other sulfonylurea) being taken.

Dosage adjustments: Increase dose gradually per glycemic control and tolerability up to a maximum dose of glyburide 20 mg/metformin 2 g per day.

Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.

Dosing: Geriatric

Use of glyburide is not recommended due to an increased risk of severe prolonged hypoglycemia (ADA 2020; Beers Criteria [AGS 2019]).

Administration

Oral: All doses should be administered with a meal. Twice-daily dosing should be administered with the morning and evening meals. Patients that are NPO or require decreased caloric intake may need doses held to avoid hypoglycemia.

Dietary Considerations

May cause GI upset; take with food to decrease GI upset. Individualized medical nutrition therapy (MNT) based on ADA recommendations is an integral part of therapy. Monitor for signs and symptoms of vitamin B12 and folic acid deficiency; supplementation may be required.

Storage

Store at ≤25°C (≤77°F). Protect from light.

Drug Interactions

Abemaciclib: May increase the serum concentration of MetFORMIN. Monitor therapy

Ajmaline: Sulfonamides may enhance the adverse/toxic effect of Ajmaline. Specifically, the risk for cholestasis may be increased. Monitor therapy

Alcohol (Ethyl): May enhance the adverse/toxic effect of MetFORMIN. Specifically, alcohol may potentiate the risk of lactic acidosis Avoid combination

Alpelisib: May decrease the serum concentration of CYP2C9 Substrates (High risk with Inducers). Monitor therapy

Alpha-Glucosidase Inhibitors: May enhance the hypoglycemic effect of Sulfonylureas. Management: Consider a decrease in sulfonylurea dose when initiating therapy with an alpha-glucosidase inhibitor and monitor patients for hypoglycemia. Consider therapy modification

Alpha-Lipoic Acid: May enhance the hypoglycemic effect of Antidiabetic Agents. Monitor therapy

Aminolevulinic Acid (Systemic): Photosensitizing Agents may enhance the photosensitizing effect of Aminolevulinic Acid (Systemic). Avoid combination

Aminolevulinic Acid (Topical): Photosensitizing Agents may enhance the photosensitizing effect of Aminolevulinic Acid (Topical). Monitor therapy

Androgens: May enhance the hypoglycemic effect of Agents with Blood Glucose Lowering Effects. Monitor therapy

Antidiabetic Agents: May enhance the hypoglycemic effect of Hypoglycemia-Associated Agents. Monitor therapy

Beta-Blockers: May enhance the hypoglycemic effect of Sulfonylureas. Cardioselective beta-blockers (eg, acebutolol, atenolol, metoprolol, and penbutolol) may be safer than nonselective beta-blockers. All beta-blockers appear to mask tachycardia as an initial symptom of hypoglycemia. Ophthalmic beta-blockers are probably associated with lower risk than systemic agents. Monitor therapy

Bictegravir: May increase the serum concentration of MetFORMIN. Monitor therapy

Bosentan: GlyBURIDE may enhance the hepatotoxic effect of Bosentan. GlyBURIDE may decrease the serum concentration of Bosentan. Bosentan may decrease the serum concentration of GlyBURIDE. Avoid combination

Carbocisteine: Sulfonylureas may enhance the adverse/toxic effect of Carbocisteine. Specifically, sulfonylureas may enhance adverse effects of alcohol that is present in liquid formulations of carbocisteine-containing products. Monitor therapy

Carbonic Anhydrase Inhibitors: May enhance the adverse/toxic effect of MetFORMIN. Specifically, the risk of developing lactic acidosis may be increased. Monitor therapy

Cephalexin: May increase the serum concentration of MetFORMIN. Monitor therapy

Chloramphenicol (Systemic): May increase the serum concentration of Sulfonylureas. Monitor therapy

Cimetidine: May increase the serum concentration of MetFORMIN. Management: Consider alternatives to cimetidine in patients receiving metformin due to a potential for increased metformin concentrations and toxicity (including lactic acidosis). Consider therapy modification

Clarithromycin: May increase the serum concentration of GlyBURIDE. Monitor therapy

Colesevelam: May decrease the serum concentration of GlyBURIDE. Management: Administer glyburide at least 4 hours prior to colesevelam. Consider therapy modification

Cyclic Antidepressants: May enhance the hypoglycemic effect of Sulfonylureas. Monitor therapy

CycloSPORINE (Systemic): May diminish the therapeutic effect of GlyBURIDE. GlyBURIDE may increase the serum concentration of CycloSPORINE (Systemic). Monitor therapy

CYP2C9 Inducers (Moderate): May decrease the serum concentration of Sulfonylureas. Monitor therapy

CYP2C9 Inhibitors (Moderate): May increase the serum concentration of Sulfonylureas. Monitor therapy

Dalfampridine: MetFORMIN may increase the serum concentration of Dalfampridine. Dalfampridine may increase the serum concentration of MetFORMIN. Monitor therapy

Dexketoprofen: May enhance the adverse/toxic effect of Sulfonamides. Monitor therapy

Dipeptidyl Peptidase-IV Inhibitors: May enhance the hypoglycemic effect of Sulfonylureas. Management: Consider a decrease in sulfonylurea dose when initiating therapy with a dipeptidyl peptidase-IV inhibitor and monitor patients for hypoglycemia. Consider therapy modification

Direct Acting Antiviral Agents (HCV): May enhance the hypoglycemic effect of Antidiabetic Agents. Monitor therapy

Dofetilide: MetFORMIN may increase the serum concentration of Dofetilide. Monitor therapy

Dolutegravir: May increase the serum concentration of MetFORMIN. Management: Consider alternatives to this combination or use of lower metformin doses. Carefully weigh the risk of metformin toxicities (including lactic acidosis) against the benefit of combining dolutegravir with metformin. Consider therapy modification

Erdafitinib: May increase the serum concentration of OCT2 Substrates. Monitor therapy

Fibric Acid Derivatives: May enhance the hypoglycemic effect of Sulfonylureas. Monitor therapy

Glucagon-Like Peptide-1 Agonists: May enhance the hypoglycemic effect of Sulfonylureas. Management: Consider sulfonylurea dose reductions when used in combination with glucagon-like peptide-1 agonists. Consider therapy modification

Glycopyrrolate (Systemic): May increase the serum concentration of MetFORMIN. Monitor therapy

Guanethidine: May enhance the hypoglycemic effect of Antidiabetic Agents. Monitor therapy

Herbs (Hypoglycemic Properties): May enhance the hypoglycemic effect of Hypoglycemia-Associated Agents. Monitor therapy

Hyperglycemia-Associated Agents: May diminish the therapeutic effect of Antidiabetic Agents. Monitor therapy

Hypoglycemia-Associated Agents: May enhance the hypoglycemic effect of other Hypoglycemia-Associated Agents. Monitor therapy

Hypoglycemia-Associated Agents: Antidiabetic Agents may enhance the hypoglycemic effect of Hypoglycemia-Associated Agents. Monitor therapy

Iodinated Contrast Agents: May enhance the adverse/toxic effect of MetFORMIN. Renal dysfunction that may be caused by iodinated contrast agents may lead to metformin-associated lactic acidosis. Management: Management advice varies. Refer to the full drug interaction monograph content for details. Consider therapy modification

Isavuconazonium Sulfate: May increase the serum concentration of MetFORMIN. Monitor therapy

LamoTRIgine: May increase the serum concentration of MetFORMIN. Management: The lamotrigine Canadian product monograph states that coadministration of these drugs is not recommended. Monitor therapy

Letermovir: May increase the serum concentration of GlyBURIDE. Monitor therapy

Lumacaftor and Ivacaftor: May decrease the serum concentration of CYP2C9 Substrates (High Risk with Inhibitors or Inducers). Lumacaftor and Ivacaftor may increase the serum concentration of CYP2C9 Substrates (High Risk with Inhibitors or Inducers). Monitor therapy

Maitake: May enhance the hypoglycemic effect of Agents with Blood Glucose Lowering Effects. Monitor therapy

Mecamylamine: Sulfonamides may enhance the adverse/toxic effect of Mecamylamine. Avoid combination

Metreleptin: May enhance the hypoglycemic effect of Sulfonylureas. Management: Sulfonylurea dosage adjustments (including potentially large decreases) may be required to minimize the risk for hypoglycemia with concurrent use of metreleptin. Monitor closely for signs or symptoms of hypoglycemia. Consider therapy modification

Miconazole (Oral): May enhance the hypoglycemic effect of Sulfonylureas. Miconazole (Oral) may increase the serum concentration of Sulfonylureas. Monitor therapy

Mitiglinide: May enhance the adverse/toxic effect of Sulfonylureas. Avoid combination

Monoamine Oxidase Inhibitors: May enhance the hypoglycemic effect of Agents with Blood Glucose Lowering Effects. Monitor therapy

Nonsteroidal Anti-Inflammatory Agents: May enhance the adverse/toxic effect of MetFORMIN. Monitor therapy

Ombitasvir, Paritaprevir, and Ritonavir: May enhance the adverse/toxic effect of MetFORMIN. Specifically, the risk for lactic acidosis may be increased. Monitor therapy

Ombitasvir, Paritaprevir, Ritonavir, and Dasabuvir: May enhance the adverse/toxic effect of MetFORMIN. Specifically, the risk for lactic acidosis may be increased. Monitor therapy

Ondansetron: May increase the serum concentration of MetFORMIN. Monitor therapy

Patiromer: May decrease the serum concentration of MetFORMIN. Management: Administer metformin at least 3 hours before or 3 hours after patiromer. Consider therapy modification

Pegvisomant: May enhance the hypoglycemic effect of Agents with Blood Glucose Lowering Effects. Monitor therapy

Porfimer: Photosensitizing Agents may enhance the photosensitizing effect of Porfimer. Monitor therapy

Probenecid: May decrease the protein binding of Sulfonylureas. Probenecid may increase the serum concentration of Sulfonylureas. Monitor therapy

Prothionamide: May enhance the hypoglycemic effect of Agents with Blood Glucose Lowering Effects. Monitor therapy

Quinolones: May enhance the hypoglycemic effect of Agents with Blood Glucose Lowering Effects. Quinolones may diminish the therapeutic effect of Agents with Blood Glucose Lowering Effects. Specifically, if an agent is being used to treat diabetes, loss of blood sugar control may occur with quinolone use. Monitor therapy

RaNITIdine (Withdrawn from US Market): May enhance the hypoglycemic effect of GlyBURIDE. Monitor therapy

Ranolazine: May increase the serum concentration of MetFORMIN. Management: Limit the metformin dose to a maximum of 1,700 mg per day when used together with ranolazine 1,000 mg twice daily. Monitor patients for metformin toxicities, including lactic acidosis and carefully weigh the risks and benefits of this combination. Consider therapy modification

Rifapentine: May decrease the serum concentration of CYP2C9 Substrates (High risk with Inducers). Monitor therapy

Risdiplam: May increase the serum concentration of MATE1 Substrates. Management: Avoid use of risdiplam with MATE substrates if possible. If the combination cannot be avoided, monitor closely for adverse effects. Consider a reduced dose of the MATE substrate according to that substrate's labeling if appropriate. Consider therapy modification

Ritodrine: May diminish the therapeutic effect of Antidiabetic Agents. Monitor therapy

Salicylates: May enhance the hypoglycemic effect of Agents with Blood Glucose Lowering Effects. Monitor therapy

Selective Serotonin Reuptake Inhibitors: May enhance the hypoglycemic effect of Agents with Blood Glucose Lowering Effects. Monitor therapy

Sodium-Glucose Cotransporter 2 (SGLT2) Inhibitors: May enhance the hypoglycemic effect of Sulfonylureas. Management: Consider a decrease in sulfonylurea dose when initiating therapy with a sodium-glucose cotransporter 2 inhibitor and monitor patients for hypoglycemia. Consider therapy modification

SORAfenib: May enhance the hypoglycemic effect of GlyBURIDE. Monitor therapy

Sulfonamide Antibiotics: May enhance the hypoglycemic effect of Sulfonylureas. Monitor therapy

Tafenoquine: May increase the serum concentration of MATE1 Substrates. Management: Avoid use of MATE substrates with tafenoquine, and if the combination cannot be avoided, monitor closely for evidence of toxicity of the MATE substrate and consider a reduced dose of the MATE substrate according to that substrate's labeling. Consider therapy modification

Tafenoquine: May increase the serum concentration of OCT2 Substrates. Management: Avoid use of OCT2 substrates with tafenoquine, and if the combination cannot be avoided, monitor closely for evidence of toxicity of the OCT2 substrate and consider a reduced dose of the OCT2 substrate according to that substrate's labeling. Consider therapy modification

Thiazide and Thiazide-Like Diuretics: May diminish the therapeutic effect of Antidiabetic Agents. Monitor therapy

Thiazolidinediones: May enhance the hypoglycemic effect of Sulfonylureas. Management: Consider sulfonylurea dose adjustments in patients taking thiazolidinediones and monitor for hypoglycemia. Consider therapy modification

Tolvaptan: May increase the serum concentration of GlyBURIDE. Management: Avoid concomitant use of the Jynarque brand of tolvaptan and OATP1B1/1B3 and OAT3 substrates. Glyburide is listed in labeling as an example of such a substrate, though the impact of these transporters on glyburide disposition in vivo is unclear. Consider therapy modification

Topiramate: May enhance the adverse/toxic effect of MetFORMIN. Monitor therapy

Trimethoprim: May increase the serum concentration of MetFORMIN. Monitor therapy

Trospium: MetFORMIN may decrease the serum concentration of Trospium. Monitor therapy

Vandetanib: May increase the serum concentration of MetFORMIN. Monitor therapy

Verapamil: May diminish the therapeutic effect of MetFORMIN. Monitor therapy

Verteporfin: Photosensitizing Agents may enhance the photosensitizing effect of Verteporfin. Monitor therapy

Vitamin K Antagonists (eg, warfarin): MetFORMIN may diminish the anticoagulant effect of Vitamin K Antagonists. Vitamin K Antagonists may enhance the hypoglycemic effect of MetFORMIN. Monitor therapy

Voriconazole: May increase the serum concentration of Sulfonylureas. Monitor therapy

Adverse Reactions

The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.

Also see individual agents.

>10%:

Endocrine & metabolic: Hypoglycemia (11% to 38%, effects higher when increased doses were used as initial therapy)

Gastrointestinal: Gastrointestinal symptoms (38%; combined GI effects increased to 38% in patients taking high doses as initial therapy), diarrhea (17%)

Respiratory: Upper respiratory infection (17%)

1% to 10%:

Central nervous system: Headache (9%), dizziness (6%)

Gastrointestinal: Nausea (8%), vomiting (8%), abdominal pain (7%)

<1%, postmarketing, and/or case reports: Cholestatic jaundice, hepatitis

ALERT: U.S. Boxed Warning

Lactic acidosis:

Post-marketing cases of metformin-associated lactic acidosis have resulted in death, hypothermia, hypotension, and resistant bradyarrhythmias. The onset of metformin-associated lactic acidosis is often subtle, accompanied only by nonspecific symptoms such as malaise, myalgias, respiratory distress, somnolence, and abdominal pain. Metformin-associated lactic acidosis was characterized by elevated blood lactate levels (greater than 5 mmol/L), anion gap acidosis (without evidence of ketonuria or ketonemia), an increased lactate:pyruvate ratio; and metformin plasma levels generally greater than 5 mcg/mL.

Risk factors for metformin-associated lactic acidosis include renal impairment, concomitant use of certain drugs (eg, carbonic anhydrase inhibitors such as topiramate), age 65 years or greater, having a radiological study with contrast, surgery and other procedures, hypoxic states (eg, acute heart failure), excessive alcohol intake, and hepatic impairment.

Steps to reduce the risk of and manage metformin-associated lactic acidosis in these high risk groups are provided in the full prescribing information.

If metformin-associated lactic acidosis is suspected, immediately discontinue glyburide/metformin and institute general supportive measures in a hospital setting. Prompt hemodialysis is recommended.

Warnings/Precautions

Concerns related to adverse effects:

• Cardiovascular mortality: Product labeling states oral hypoglycemic drugs may be associated with an increased cardiovascular mortality as compared to treatment with diet alone or diet plus insulin. Data to support this association are limited, and several studies, including a large prospective trial (UKPDS 1998), have not supported an association. Metformin does not appear to share this risk. In patients with established atherosclerotic cardiovascular disease (ASCVD), agents other than sulfonylureas are preferred (ADA 2020).

• Hypoglycemia: All sulfonylurea drugs are capable of producing severe hypoglycemia. Hypoglycemia is more likely to occur when caloric intake is deficient, after severe or prolonged exercise, when ethanol is ingested, or when more than one glucose-lowering drug is used. It is also more likely in elderly patients, malnourished or debilitated patients, and in patients with impaired renal, hepatic, adrenal, and/or pituitary function; use with caution.

• Lactic acidosis: [US Boxed Warning]: Postmarketing cases of metformin-associated lactic acidosis have resulted in death, hypothermia, hypotension, and resistant bradyarrhythmias. The onset is often subtle, accompanied by nonspecific symptoms (eg, malaise, myalgias, respiratory distress, somnolence, abdominal pain); elevated blood lactate levels (>5 mmol/L); anion gap acidosis (without evidence of ketonuria or ketonemia); increased lactate:pyruvate ratio; metformin plasma levels generally >5 mcg/mL. Risk factors for lactic acidosis include patients with renal impairment, concomitant use of certain drugs (eg, carbonic anhydrase inhibitors such as topiramate), ≥65 years, having a radiologic study with contrast, surgery and other procedures, hypoxic states (eg, acute heart failure), excessive alcohol intake, and hepatic impairment. Discontinue immediately if lactic acidosis is suspected; prompt hemodialysis is recommended. Lactic acidosis should be suspected in any patient with diabetes receiving metformin with evidence of acidosis but without evidence of ketoacidosis. Discontinue metformin in patients with conditions associated with dehydration, sepsis, or hypoxemia. The risk of accumulation and lactic acidosis increases with the degree of impairment of renal function and the patient's age.

• Sulfonamide (“sulfa”) allergy: The FDA-approved product labeling for many medications containing a sulfonamide chemical group includes a broad contraindication in patients with a prior allergic reaction to sulfonamides. There is a potential for cross-reactivity between members of a specific class (eg, two antibiotic sulfonamides). However, concerns for cross-reactivity have previously extended to all compounds containing the sulfonamide structure (SO2NH2). An expanded understanding of allergic mechanisms indicates cross-reactivity between antibiotic sulfonamides and nonantibiotic sulfonamides may not occur or at the very least this potential is extremely low (Brackett 2004; Johnson 2005; Slatore 2004; Tornero 2004). In particular, mechanisms of cross-reaction due to antibody production (anaphylaxis) are unlikely to occur with nonantibiotic sulfonamides. T-cell-mediated (type IV) reactions (eg, maculopapular rash) are less well understood and it is not possible to completely exclude this potential based on current insights. In cases where prior reactions were severe (Stevens-Johnson syndrome/TEN), some clinicians choose to avoid exposure to these classes.

• Vitamin B12 concentrations: Long-term metformin use is associated with vitamin B12 deficiency; monitor vitamin B12 serum concentrations periodically with long-term therapy. Monitoring of B12 serum concentrations should be considered in all patients receiving metformin and in particular those with peripheral neuropathy or anemia (ADA 2020).

Disease-related concerns:

• Bariatric surgery:

– Altered absorption: Use IR formulations after surgery to minimize the potential effects of bypassing stomach and proximal small bowel with gastric bypass or more rapid gastric emptying and proximal small bowel transit with sleeve gastrectomy (Apovian 2015). ER tablets may have a reduced effect due to these procedures (Mechanick 2013; Melissas 2013). After gastric bypass (Roux-en-Y gastric bypass [RYGB]), administration of IR tablets led to increased absorption (AUC0- increased by 21%) and bioavailability (increased by 50%) (Padwal 2011). ER formulations may have altered release and absorption patterns after gastric bypass or sleeve gastrectomy (but not gastric band). Compared to control, Tmax in a gastric bypass cohort administered tolbutamide was significantly shorter (1.4 ± 1.8 vs 5.1 ± 1.7 hours; P < 0.001), while Cmax and AUC0- were not altered (Tandra2013). Lactate levels decrease after gastric bypass (RYGB)-induced weight loss irrespective of the use of metformin. Routinely lowering metformin dose after gastric bypass is not necessary as long as normal renal function is preserved (Deden 2018).

– Hypoglycemia: Use an antidiabetic agent without the potential for hypoglycemia if possible; hypoglycemia may occur after gastric bypass, sleeve gastrectomy, and gastric band (Mechanick 2013). Insulin secretion and sensitivity may be partially or completely restored after these procedures (gastric bypass is most effective, followed by sleeve and finally band) (Korner 2009; Peterli 2012). First-phase insulin secretion and hepatic insulin sensitivity have been shown to be significantly improved in the immediate days after gastric bypass and sleeve gastrectomy. The restorative effects of these procedures on peripheral insulin sensitivity may occur later in the 3- to 12-month period postsurgery (Mingrone 2016).

– Weight gain: Evaluate risk vs benefit and consider alternative therapy after gastric bypass, sleeve gastrectomy, and gastric banding; weight gain may occur (Apovian 2015).

• Glucose-6-phosphate dehydrogenase (G6PD) deficiency: Patients with G6PD deficiency may be at an increased risk of sulfonylurea-induced hemolytic anemia; however, cases have also been described in patients without G6PD deficiency during postmarketing surveillance. Avoid use in patients with G6PD deficiency.

• Heart failure: Metformin may be used in patients with stable heart failure (HF); avoid use in unstable or hospitalized patients with HF (ADA 2020). Risk of lactic acidosis may be increased secondary to hypoperfusion. In a scientific statement from the American Heart Association, metformin has been determined to be an agent that may exacerbate underlying myocardial dysfunction (magnitude: major) (AHA [Page 2016]). Use of metformin in patients with HF may be associated with reduced mortality and reduction in hospital readmission for HF (Crowley 2017; Eurich 2013).

• Hepatic impairment: The metabolism and excretion of glyburide may be slowed in patients with hepatic impairment; if hypoglycemia should occur in such patients, it may be prolonged. The manufacturer recommends to avoid metformin use in patients with hepatic impairment due to potential for lactic acidosis. However, continued use of metformin in patients with diabetes with liver dysfunction, including cirrhosis, may be associated with a survival benefit in carefully selected patients (Brackett 2010; Crowley 2017; Zhang 2014).

• Renal impairment: The metabolism and excretion of glyburide may be slowed in patients with renal impairment and its active metabolites may accumulate in advanced renal insufficiency (Snyder 2004). If hypoglycemia should occur, it may be prolonged. Use of glyburide is generally not recommended in chronic kidney disease (ADA [Tuttle 2014]]; Alsahli 2015; KDOQI [Nelson 2012]). Metformin is substantially excreted by the kidney and use is contraindicated in patients with eGFR <30 mL/minute/1.73 m2. Use of concomitant medications that may affect renal function (ie, affect tubular secretion) may also affect metformin disposition. Metformin should be withheld in patients with dehydration and/or prerenal azotemia.

• Stress-related states: It may be necessary to discontinue therapy and administer insulin if the patient is exposed to stress (fever, trauma, infection, surgery).

Special populations:

• Elderly: Use of glyburide is not recommended in elderly patients due to an increased risk of severe prolonged hypoglycemia (ADA 2020; Beers Criteria [AGS 2019]). Use metformin with caution; risk of metformin-associated lactic acidosis increases with age.

Other warnings/precautions:

• Appropriate use: Not indicated for use in patients with type 1 diabetes mellitus or with diabetic ketoacidosis (DKA).

• Ethanol use: Instruct patients to avoid excessive acute or chronic ethanol use; ethanol may potentiate metformin's effect on lactate metabolism.

• Iodinated contrast: According to the manufacturer, it is recommended to temporarily discontinue metformin at the time of or before iodinated contrast imaging procedures in patients with an eGFR 30 to 60 mL/minute/1.73 m2; or with a history of hepatic disease, alcoholism, or heart failure; or in patients who will receive intra-arterial iodinated contrast. Reevaluate eGFR 48 hours after imaging procedure; restart if renal function is stable. Alternatively, the American College of Radiology (ACR) guidelines recommend that metformin may be used prior to or following administration of iodinated contrast media in patients with no evidence of acute kidney injury (AKI) and with an eGFR ≥30 mL/minute/1.73 m2; ACR guidelines recommend temporary discontinuation of metformin in patients with known AKI or severe chronic kidney disease ([stage IV or V [ie, eGFR <30 mL/minute/1.73 m2]) or who are undergoing arterial catheter studies (ACR 2017).

• Surgical procedures: Metformin-containing products should be withheld the day of surgery; restart after renal function is stable (ADA 2020).

Monitoring Parameters

Signs and symptoms of hypoglycemia, blood glucose, HbA1c (at least twice yearly in patients who have stable glycemic control and are meeting treatment goals; quarterly in patients not meeting treatment goals or with therapy change [ADA 2020]). Renal function (eGFR) should be performed prior to initiation of therapy and at least annually (more often in patients at risk of developing renal impairment; every 3 to 6 months if eGFR 45 to <60 mL/minute/1.73 m2; every 3 months if eGFR 30 to <45 mL/minute/1.73 m2 [Lipska 2011]). Initial and periodic monitoring of hematologic parameters (eg, hemoglobin/hematocrit and red blood cell indices) and hepatic function should be performed; monitor at least annually once patient is on maintenance therapy. Monitor vitamin B12 concentrations (at 2- to 3-year intervals) and folate (if megaloblastic anemia is suspected).

Reproductive Considerations

Based on the metformin component, ovulation rates may increase in some anovulatory females; contraception should be discussed for women who do not wish to conceive (ACOG 194 2018).

Pregnancy Considerations

If exposure during pregnancy occurs, discontinue at least 2 weeks prior to expected delivery. Refer to individual monographs for additional information.

Patient Education

What is this drug used for?

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

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Headache

• Abdominal pain

• Nausea

• Vomiting

• Diarrhea

• Common cold symptoms

• Dizziness

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Lactic acidosis like fast breathing, fast heartbeat, abnormal heartbeat, vomiting, fatigue, shortness of breath, severe loss of strength and energy, severe dizziness, feeling cold, or muscle pain or cramps

• Liver problems like dark urine, fatigue, lack of appetite, nausea, abdominal pain, light-colored stools, vomiting, or yellow skin

• Low blood sugar like dizziness, headache, fatigue, feeling weak, shaking, fast heartbeat, confusion, increased hunger, or sweating

• Severe loss of strength and energy

• Vision changes

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.

Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.

Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine 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 limited summary of general information about the medicine's uses from the patient education leaflet and is not intended to be comprehensive. This limited summary does NOT include all information available about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not intended to provide medical advice, diagnosis or treatment and does not replace information you receive from the healthcare provider. For a more detailed summary of information about the risks and benefits of using this medicine, please speak with your healthcare provider and review the entire patient education leaflet.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.