September 17, 2014
Patients on Sulfonylureas Frequently Prescribed
Inappropriate Antimicrobials 

Galveston, TX—Pharmacists should keep a close watch on which antimicrobial drugs are prescribed to older diabetics also using a glipizide or glyburide.

A new retrospective cohort study of Texas Medicare claims, published ahead of print recently by JAMA Internal Medicine, found that inappropriate medications were prescribed more than a quarter of the time, despite the risk of those drugs interacting with sulfonylureas and increasing the risk of hypoglycemia.

“Prescription of interacting antimicrobial drugs to patients on sulfonylureas is very common, and is associated with substantial morbidity and increased costs,” write the authors from the University of Texas Medical Branch in Galveston.

To determine the risk of hypoglycemia and associated costs, the researchers reviewed claims from 2006 to 2009 for patients 66 years or older who were prescribed glipizide or glyburide and who also filled a prescription for one of the 16 antimicrobials most commonly prescribed for this population. Noninteracting antimicrobials were used as a comparison, with the primary outcomes being any hospitalization or emergency department visit owing to hypoglycemia within 14 days of antimicrobial exposure.

In multivariable analyses controlling for patient characteristics and indication for antimicrobial drug use, higher rates of hypoglycemia were found with clarithromycin (odds ratio [OR] of 3.96), levofloxacin (OR of 2.60), sulfamethoxazole-trimethoprim (OR of 2.56), metronidazole (OR of 2.11), and ciprofloxacin (OR of 1.62) compared with noninteracting antimicrobials.

According to the results, the number needed to harm ranged from 71 for clarithromycin to 334 for ciprofloxacin.

Hypoglycemia was especially common in older females who were black or Hispanic and had more comorbidities as well as prior episodes of low blood sugar.

The study points out that in 2009, 28.3% of patients prescribed a sulfonylurea also filled a prescription for one of those five antimicrobials, which were associated with 13.2% of all hypoglycemia events in patients taking sulfonylureas.

In addition to creating life-threatening events for patients, the practice also has a steep monetary cost. The authors point out that treatment of subsequent hypoglycemia added $30.54 in additional Medicare costs to each prescription of one of those five antimicrobials given to patients taking sulfonylureas.

U.S. Pharmacist Social Connect