BOXED WARNING Metformin Hydrochloride Lactic acidosis: Lactic acidosis is a rare, but serious, metabolic complication that can occur due to metformin accumulation during treatment with Glipizide and Metformin HCl Tablets; when it occurs, it is fatal in approximately 50% of cases. Lactic acidosis may also occur in association with a number of pathophysiologic conditions, including diabetes mellitus, and whenever there is significant tissue hypoperfusion and hypoxemia. Lactic acidosis is characterized by elevated blood lactate levels (>5 mmol/L), decreased blood pH, electrolyte disturbances with an increased anion gap, and an increased lactate/pyruvate ratio. When metformin is implicated as the cause of lactic acidosis, metformin plasma levels >5 μg/mL are generally found. The reported incidence of lactic acidosis in patients receiving Metformin hydrochloride is very low (approximately 0.03 cases/1000 patient-years, with approximately 0.015 fatal cases/1000 patient-years). In more than 20,000 patient-years exposure to metformin in clinical trials, there were no reports of lactic acidosis. Reported cases have occurred primarily in diabetic patients with significant renal insufficiency, including both intrinsic renal disease and renal hypoperfusion, often in the setting of multiple concomitant medical/surgical problems and multiple concomitant medications. Patients with congestive heart failure requiring pharmacologic management, in particular those with unstable or acute congestive heart failure who are at risk of hypoperfusion and hypoxemia, are at increased risk of lactic acidosis. The risk of lactic acidosis increases with the degree of renal dysfunction and the patient's age. The risk of lactic acidosis may, therefore, be significantly decreased by regular monitoring of renal function in patients taking metformin and by use of the minimum effective dose of metformin. In particular, treatment of the elderly should be accompanied by careful monitoring of renal function. Glipizide and Metformin HCl Tablets treatment should not be initiated in patients ≥80 years of age unless measurement of creatinine clearance demonstrates that renal function is not reduced, as these patients are more susceptible to developing lactic acidosis. In addition, Glipizide and Metformin HCl Tablets should be promptly withheld in the presence of any condition associated with hypoxemia, dehydration, or sepsis. Because impaired hepatic function may significantly limit the ability to clear lactate, Glipizide and Metformin HCl Tablets should generally be avoided in patients with clinical or laboratory evidence of hepatic disease. Patients should be cautioned against excessive alcohol intake, either acute or chronic, when taking Glipizide and Metformin HCl Tablets, since alcohol potentiates the effects of metformin hydrochloride on lactate metabolism. In addition, Glipizide and Metformin HCl Tablets should be temporarily discontinued prior to any intravascular radiocontrast study and for any surgical procedure (see also PRECAUTIONS). The onset of lactic acidosis often is subtle, and accompanied only by nonspecific symptoms such as malaise, myalgias, respiratory distress, increasing somnolence, and nonspecific abdominal distress. There may be associated hypothermia, hypotension, and resistant bradyarrhythmias with more marked acidosis. The patient and the patient's physician must be aware of the possible importance of such symptoms and the patient should be instructed to notify the physician immediately if they occur (see also PRECAUTIONS). Glipizide and Metformin HCl Tablets should be withdrawn until the situation is clarified. Serum electrolytes, ketones, blood glucose, and if indicated, blood pH, lactate levels, and even blood metformin levels may be useful. Once a patient is stabilized on any dose level of Glipizide and Metformin HCl Tablets, gastrointestinal symptoms, which are common during initiation of therapy with metformin, are unlikely to be drug related. Later occurrence of gastrointestinal symptoms could be due to lactic acidosis or other serious disease. Levels of fasting venous plasma lactate above the upper limit of normal but less than 5 mmol/L in patients taking Glipizide and Metformin HCl Tablets do not necessarily indicate impending lactic acidosis and may be explainable by other mechanisms, such as poorly controlled diabetes or obesity, vigorous physical activity, or technical problems in sample handling. (See also PRECAUTIONS.) Lactic acidosis should be suspected in any diabetic patient with metabolic acidosis lacking evidence of ketoacidosis (ketonuria and ketonemia). Lactic acidosis is a medical emergency that must be treated in a hospital setting. In a patient with lactic acidosis who is taking Glipizide and Metformin HCl Tablets, the drug should be discontinued immediately and general supportive measures promptly instituted. Because metformin hydrochloride is dialyzable (with a clearance of up to 170 mL/min under good hemodynamic conditions), prompt hemodialysis is recommended to correct the acidosis and remove the accumulated metformin. Such management often results in prompt reversal of symptoms and recovery. ( See also CONTRAINDICATIONS and PRECAUTIONS .)
ADVERSE REACTIONS Glipizide and Metformin HCl Tablets In a double-blind 24-week clinical trial involving Glipizide and Metformin HCl Tablets as initial therapy, a total of 172 patients received Glipizide and Metformin HCl Tablets 2.5 mg/250 mg, 173 received Glipizide and Metformin HCl Tablets 2.5 mg/500 mg, 170 received glipizide, and 177 received metformin. The most common clinical adverse events in these treatment groups are listed in Table 4 . Table 4: Clinical Adverse Events >5% in any Treatment Group, by Primary Term, in Initial Therapy Study Adverse Event Number (%) of Patients Glipizide Metformin Glipizide and Glipizide and 5 mg 500 mg Metformin HCl Metformin tablets tablets 2.5 mg/250 mg HCl N=170 N=177 tablets 2.5 mg/500 mg N=172 tablets N=173 Upper respiratory infection 12 (7.1) 15 (8.5) 17 (9.9) 14 (8.1) Diarrhea 8 (4.7) 15 (8.5) 4 (2.3) 9 (5.2) Dizziness 9 (5.3) 2 (1.1) 3 (1.7) 9 (5.2) Hypertension 17 (10.0) 10 (5.6) 5 (2.9) 6 (3.5) Nausea/vomiting 6 (3.5) 9 (5.1) 1 (0.6) 3 (1.7) In a double-blind 18-week clinical trial involving Glipizide and Metformin HCl Tablets as second-line therapy, a total of 87 patients received Glipizide and Metformin HCl Tablets, 84 received glipizide, and 75 received metformin. The most common clinical adverse events in this clinical trial are listed in Table 5 . Table 5: Clinical Adverse Events >5% in any Treatment Group, by Primary Term, in Second-Line Therapy Study Adverse Event Number (%) of Patients Glipizide Metformin Glipizide and 5 mg 500 mg Metformin HCl tablets a tablets a 5 mg/500 mg N=84 N=75 tablets a N=84 N=75 N=87 Diarrhea 11 (13.1) 13 (17.3) 16 (18.4) Headache 5 (6.0) 4 (5.3) 11 (12.6) Upper respiratory infection 11 (13.1) 8 (10.7) 9 (10.3) Musculoskeletal pain 6 (7.1) 5 (6.7) 7 (8.0) Nausea/vomiting 5 (6.0) 6 (8.0) 7 (8.0) Abdominal pain 7 (8.3) 5 (6.7) 5 (5.7) UTI 4 (4.8) 6 (8.0) 1 (1.1) Hypoglycemia In a controlled initial therapy trial of Glipizide and Metformin HCl Tablets 2.5 mg/250 mg and 2.5 mg/500 mg the numbers of patients with hypoglycemia documented by symptoms (such as dizziness, shakiness, sweating, and hunger) and a fingerstick blood glucose measurement ≤50 mg/dL were 5 (2.9%) for glipizide, 0 (0%) for metformin, 13 (7.6%) for Glipizide and Metformin HCl Tablets 2.5 mg/250 mg, and 16 (9.3%) for Glipizide and Metformin HCl Tablets 2.5 mg/500 mg. Among patients taking either Glipizide and Metformin HCl Tablets.2.5 mg/250 mg or Glipizide and Metformin HCl Tablets 2.5 mg/500 mg, 9 (2.6%) patients discontinued Glipizide and Metformin HCl Tablets due to hypoglycemic symptoms and one required medical intervention due to hypoglycemia. In a controlled second-line therapy trial of Glipizide and Metformin HCl Tablets 5 mg/500 mg, the numbers of patients with hypoglycemia documented by symptoms and a fingerstick blood glucose measurement ≤50 mg/dL were 0 (0%) for Glipizide, 1 (1.3%) for metformin, and 11 (12.6%) for Glipizide and Metformin HCl Tablets. One (1.1%) patient discontinued Glipizide and Metformin HCl Tablets therapy due to hypoglycemic symptoms and none required medical intervention due to hypoglycemia. (See PRECAUTIONS .) Gastrointestinal Reactions Among the most common clinical adverse events in the initial therapy trial were diarrhea and nausea/vomiting; the incidences of these events were lower with both Glipizide and Metformin HCl Tablets dosage strengths than with metformin therapy. There were 4 (1.2%) patients in the initial therapy trial who discontinued Glipizide and Metformin HCl Tablets therapy due to Gastrointestinal (GI) adverse events. Gastrointestinal symptoms of diarrhea, nausea/vomiting, and abdominal pain were comparable among Glipizide and Metformin HCl Tablets, glipizide and metformin in the second-line therapy trial. There were 4 (4.6%) patients in the second-line therapy trial who discontinued Glipizide and Metformin HCl Tablets therapy due to GI adverse events.