Comprehensive Nursing Pharmacology Q 28

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Which of the following adverse effects is specific to the biguanide diabetic drug metformin (Glucophage) therapy?

  

     A. Hypoglycemia

     B. Lactic acidosis

     C. GI distress

     D. Somnolence

    

    

Correct Answer: B . Lactic acidosis

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Lactic acidosis is the most dangerous adverse effect of metformin administration with death resulting in approximately 50 percent of individuals who develop lactic acidosis while on this drug. Metformin has a black box warning for lactic acidosis. This side effect is rare but serious and has an incident rate of 1/30,000 patients. Lactate builds up in the body and cannot be eliminated easily, which leads to metabolic acidosis. This lowering of pH in the blood can cause nonspecific signs and symptoms, which include malaise, respiratory distress, elevated lactate levels, and anion gap acidosis.

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Option A: Metformin does not induce insulin production; thus, the administration does not result in hypoglycemic events. Metformin is a biguanide drug that reduces blood glucose levels by decreasing the production of glucose in the liver, decreasing intestinal absorption, and increasing insulin sensitivity. Metformin decreases both basal and postprandial blood glucose.

Option C: Some nausea, vomiting, and diarrhea may develop but is usually not severe. Gastrointestinal side effects, including diarrhea, nausea, and vomiting, are very common and typically occur in up to 30% of patients taking metformin.

Option D: Metformin does not induce sleepiness. Occurring less frequently, some patients experience chest discomfort, headache, diaphoresis, hypoglycemia, weakness, and rhinitis. Decreased vitamin B12 levels are associated with long-term metformin and should be monitored, particularly in anemic or peripheral neuropathy patients. Supplementation of vitamin B12 may be necessary.

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