Glipizide and metformin and Lactic acidosis

The use of metformin is contraindicated in patients with renal dysfunction (serum creatinine >= 1.5 mg/dL in males and 1.4 mg/dL in females, or above the upper limit of normal for age); congestive heart failure requiring pharmacologic treatment (especially unstable or acute CHF where there is risk of hypoperfusion and hypoxemia); and any condition associated with hypoxemia (e.g., severe anemia, myocardial infarction, asphyxia, shock), dehydration (e.g., severe diarrhea or vomiting), or sepsis. Patients with these conditions may be at increased risk for the development of lactic acidosis, which is a rare but serious metabolic complication associated with metformin accumulation in plasma usually at levels exceeding 5 mcg/mL. Metformin should also not be administered to patients with acute or chronic metabolic acidosis. In addition, metformin should generally be avoided in alcoholics and patients with clinical or laboratory evidence of hepatic disease, since alcohol potentiates the effects of metformin on lactate metabolism and impaired hepatic function may significantly limit the ability to clear lactate. All patients treated with metformin should have renal function monitored regularly (at least annually or more frequently if necessary) and be advised of the significance of nonspecific symptoms such as malaise, myalgias, respiratory distress, increasing somnolence, and gastrointestinal disturbances that arise after stabilization of metformin dosage. More marked acidosis may be associated with hypothermia, hypotension, and resistant bradyarrhythmias. Immediate medical attention is necessary if these symptoms occur, and metformin therapy withheld until the situation can be clarified. If lactic acidosis is diagnosed, prompt supportive measures and hemodialysis are recommended.