Lactic acidosis is a rare, but serious, metabolic complication that can occur due to metformin accumulation during treatment with METAGLIP; 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. METAGLIP 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, METAGLIP 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, METAGLIP 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 METAGLIP, since alcohol potentiates the effects of metformin hydrochloride on lactate metabolism. In addition, METAGLIP 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). METAGLIP 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 METAGLIP, 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 METAGLIP 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 METAGLIP, 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.)
Published Studies Related to Metaglip (Glipizide / Metformin)
Effect on glycemic control of the addition of 2.5 mg glipizide GITS to metformin in patients with T2DM. [2005.05]
AIMS: This study evaluated the effects on glycemic control of the addition of 2.5 mg glipizide GITS to metformin in patients with mild-to-moderate, but suboptimally controlled type 2 diabetes... CONCLUSIONS: This study showed that the addition of 2.5 mg glipizide GITS to metformin significantly improved glucose control in patients with type 2 diabetes inadequately controlled by metformin monotherapy.
Multicenter, randomized, double-masked, parallel-group assessment of simultaneous glipizide/metformin as second-line pharmacologic treatment for patients with type 2 diabetes mellitus that is inadequately controlled by a sulfonylurea. [2003.03]
BACKGROUND: Many patients with type 2 diabetes mellitus (DM) with inadequate long-term blood glucose control with sulfonylurea or metformin monotherapy require additional treatment. The synergistic effects of combining glipizide with metformin on glucose control may be realized by treating the primary effects of type 2 DM, impaired insulin secretion, and insulin resistance. OBJECTIVE: This study assessed therapy with glipizide/metformin combination tablets in patients with type 2 DM that is uncontrolled by at least half the maximum labeled daily dose of a sulfonylurea... CONCLUSIONS: Glipizide/metformin tablets were more effective than either glipizide or metformin monotherapy in controlling HbA1c and in reducing FPG compared with baseline in patients with blood glucose that was uncontrolled with previous sulfonylurea treatment. In addition, patients receiving glipizide/ metformin were more likely to achieve an HbA1c level < 7.0%. These results were consistent with the synergistic effects on insulin resistance and beta cell dysfunction. Glipizide/metformin was well tolerated, with a low incidence of hypoglycemia.
Effect of combination glipizide GITS/metformin on fibrinolytic and metabolic parameters in poorly controlled type 2 diabetic subjects. [2002.12]
CONCLUSIONS: When hyperglycemia is profound, increases in PAI-1 are also profound. Control of hyperglycemia with either glipizide GITS, an insulin secretagogue, or metformin as monotherapy comparably ameliorates elevated PAI-1.
One year comparative trial of metformin and glipizide in type 2 diabetes mellitus. [1994.07]
Forty-eight diabetic subjects with diet-failed Type 2 mellitus, aged 40-69 years, were randomised to metformin (24 patients) or glipizide (24 patients) therapy, and followed prospectively for 12 months. Most subjects were obese... In conclusion, metformin gave better glycaemic control than glipizide, with weight loss rather than weight gain in obese Type 2 patients.
Glipizide. A review of the pharmacoeconomic implications of the extended-release formulation in type 2 diabetes mellitus. [2000.09]
CONCLUSIONS: Glipizide GITS produced better cost outcomes than metformin and acarbose in a model of 3 years' treatment of type 2 diabetes mellitus. Glipizide GITS had pharmacoeconomic and quality of life advantages over diet alone in the short term, but more clinically relevant comparisons with other antidiabetic agents are needed. There are limitations to the present data, but the available pharmacoeconomic data have been favourable for glipizide GITS.