To help clinicians weigh the benefits and risks of the diabetes drug Byetta (exenatide), FDA is requiring that information about the risk of renal impairment be added to the drug’s labeling.

From April 2005 to October 2008, FDA received 78 reports of altered kidney function in patients treated with Byetta. Some of the patients had pre-existing kidney disease and other risk factors for developing kidney problems. Acute renal failure occurred in 62 patients and renal insufficiency in 16 patients.

More than 6.6 million Byetta prescriptions were dispensed during this same time period, so these cases represent a small percentage of the total number of patients treated with the drug.

Here’s what the drug’s labeling says. Byetta should not be used in patients with severe renal impairment or end-stage renal disease. For patients with moderate renal impairment, use caution when starting Byetta or increasing the dose from 5 mcg to 10 mcg.

Monitor patients for signs and symptoms of altered kidney function, including increased serum creatinine, changes in urination, unexplained swelling, increases in blood pressure, lethargy, or dull ache in the mid to lower back. Consider discontinuing the drug if a patient’s kidney function worsens while using it.

Patients receiving Byetta should be told to watch for the signs and symptoms of altered kidney function and report these to their healthcare professional. Patients should also report nausea and vomiting, because these could lead to dehydration and increase the risk of impaired kidney function.