NXL101

NXL101 is a novel small molecule nonfluoroquinolone antibiotic that was developed by Novexel, a company spun out from Sanofi-Aventis. It belongs to the quinoline class and functions by inhibiting bacterial type II topoisomerases, specifically DNA gyrase and topoisomerase IV, which are critical for bacterial DNA replication. The drug was primarily investigated for the treatment of serious Gram-positive infections, including methicillin-resistant *Staphylococcus aureus* (MRSA) and fluoroquinolone-resistant strains. NXL101 was designed for both intravenous and oral administration. However, its development was terminated in 2008 during early clinical trials after healthy subjects exhibited QT interval prolongation, a potential precursor to serious cardiac arrhythmias.