A repurposed FDA-approved drug shows promise in killing antibiotic resistant bacteria

A new study from Emory University addresses the growing global crisis of antibiotic-resistant infections. Many of these drug-resistant bacteria are spread through hospitals, and there are few antibiotics available for treatment.

The study, published in PNAS, looks at a particular bacterium called Acinetobacter baumannii, which is highly infectious, spread mostly in hospitals and typically infects immunocompromised patients. The researchers employed an entirely new strategy to identify weaknesses specific to resistant bacteria and then target these weaknesses with an alternate drug. They found that fendiline, a drug that acts as a calcium channel blocker and formerly used to treat heart arrhythmia kills the bacterium by targeting the essential lipoprotein trafficking pathway, which is weakened in antibiotic resistant bacteria.

What the researchers say

“it’s critical that we find more and better therapeutics that can target these antibiotic-resistant infections which affect patients on ventilators, those with deep soft tissue infections, and the immunocompromised,” says Philip Rather, PhD, corresponding author on the paper and professor in the Emory University School of Medicine.

“This novel finding repurposes an existing drug, exploits a newly identified vulnerability in an antibiotic-resistant bacterium, and opens doors for developing new antibiotics targeting similar pathways,” says Jennifer Colquhoun, PhD, first author and research scientist at Emory University.

Why it matters

• The discovery that fendiline can selectively kill drug-resistant bacteria suggests a fast-track potential for treating infections that are currently difficult or impossible to manage with existing antibiotics.
• Since fendiline is already FDA-approved, there is potential for quicker clinical trials and deployment in treating serious hospital-acquired infections, particularly in immunocompromised patients.
• The drug selectively targets the specific bacterium, leaving the healthy bacteria in a patients gut flora intact.

Citation: Colquhoun et al., “Repurposing a drug to punish carbapenem-resistant Acinetobacter baumannii,” Proceeding of the National Academy of Sciences (PNAS). June 10, 2025. doi.org/10.1073/pnas.2423650122