Anecdotal evidence and voluntary postmarketing studies reported to the US Food and Drug Administration (FDA) have suggested that fluoroquinolones -- and gatifloxacin in particular -- are associated with an increased risk of hypoglycemia in older patients.

To address that question in a prospective manner, researchers led by Mark C. Decerbo, PharmD, assistant professor of pharmacy practice, University of Southern Nevada, Henderson, Nevada, enrolled 196 patients over the age of 65 who were being treated with gatifloxacin or a nonfluoquinolone antibiotic at the hospital.

Of the 77 patients in the gatifloxacin arm, 13% developed hypoglycemia compared with 0.8% of 119 patients on nonfluoroquinolone antibiotic.

Patients with type 2 diabetes were more likely to become hypoglycemic after antibiotic dosing. In the gatifloxacin arm, 32% of 22 patients with diabetes became hypoglycemic compared with 5% of the 55 patients who were not diabetic. Of 41 diabetic patients in the control arm, 2% became hypoglycemic, compared with none of the 78 nondiabetic patients.

"A relationship exists between gatifloxacin therapy and development of hypoglycemia within 48 hours of the initial dose of this antibiotic in patients over 65 years old," concluded Dr. Decerbo, who presented the results here on October 7^th. The presence of diabetes increases that risk significantly, he added.

Other individual fluoroquinolones have been associated with particular adverse effects, which suggests that "not all fluoroquinolones are created equal," Dr. Decerbo said. He said that gatifloxacin is uniquely able to provoke hypoglycemia in elderly patients, which may be a reason to avoid its use in this population.

One caveat, he noted, is that researchers tested blood glucose levels in diabetic patients 4 times daily, but only once per day in nondiabetic individuals, which might have led to undetected cases of hypoglycemia in the nondiabetic population.

Also, the study covered a nonrandomized sample of patients, which could have led to unnoticed confounding variables. However, the groups were well matched in terms of demographic characteristics, Dr. Decerbo said.

Hypoglycemia was detected in patients who were on 200-mg/day gatifloxacin as well as the standard 400-mg dose, he said.


[Presentation title: Rate of Early-Onset Hypoglycemia Associated with Gatifloxacin Versus Non-Fluoroquinolone Antibiotics in Elderly Patients. Abstract 125]

Copyright © 2009 P\S\L Consulting Group Inc. All rights reserved. Republication or redistribution of P\S\L content is expressly prohibited without the prior written consent of P\S\L. P\S\L shall not be liable for any errors, omissions or delays in this content or any other content on its sites, newsletters or other publications, nor for any decisions or actions taken in reliance on such content.