Gemifloxacin, as a member of the fluoroquinolone class, acts by inhibiting bacterial topoisomerase IV and DNA gyrase. These enzymes are required for DNA replication, transcription, repair, and recombination.

Acute Exacerbations of Chronic Bronchitis: Emerging therapies

Despite the large patient populations with respiratory tract infections (RTIs), in recent years, many biopharmaceutical companies have shifted development effort away from RTIs to pursue other disease areas with perceived higher unmet need (e.g., resistant hospital-acquired infections). Likewise, many companies have shifted away from antibacterial drug development in favor of chronic disease markets perceived to have higher return on investment.

Dihydrofolate Reductase Inhibitors

The dihydrofolate reductase (DHFR) inhibitors target bacterial DHFR, an enzyme involved in the folic acid pathway, thereby disrupting bacterial replication. DHFR inhibitors target both gram-positive and gram negative-bacteria and hence could serve as broad-spectrum antibacterials.


Tetracyclines are the prototypical broad-spectrum antibiotic and are occasionally used as first-line agents in some markets (e.g., Germany) for the treatment of mild acute exacerbations of chronic bronchitis, particularly when cost, penicillin hypersensitivity, and β-lactam resistance are of concern. The widespread use of tetracyclines has resulted in a steady increase in the prevalence of resistance to these agents. Therefore, empiric use of tetracyclines is usually restricted to regions where resistance levels remain low or when other appropriate antibiotics are contraindicated.