One of the most widely used diabetes drugs may be incorrectly prescribed to one-fourth of the patients taking it, causing potentially life-threatening complications, a new study warns.
The drug, metformin (Glucophage), can trigger a buildup of lactic acid in the blood of patients with poor kidney function or congestive heart failure. The condition, called lactic acidosis, is fatal in nearly half of cases.
Researchers from the University of North Carolina at Chapel Hill, who studied the prescriptions of 100 diabetic patients, found that nearly one in four people who took metformin had either limited kidney function or congestive heart failure. "We were surprised the numbers were so high," said Dr. Russell Rothman, a study co-author and a health researcher at the university.
The findings were reported in last week's Journal of the American Medical Assn.
More than 25 million prescriptions were written for metformin in 2000; the drug helps lower the blood's sugar level.
The drug's package insert carries a warning alerting doctors to this potential complication. "Most physicians don't bother to read the package inserts," says Rothman. "We prescribe thousands of drugs so it's very hard to keep up with all the contraindications."
Lactic acidosis triggered by metformin is quite rare, however, and occurs in only one in 10,000 cases. Consequently, "patients shouldn't blow this out of proportion," says Dr. Christopher D. Saudek, president of the American Diabetes Assn. and professor of medicine at Johns Hopkins University in Baltimore. "They should talk to their doctors before making any changes in their medications."