Polymyxins have re-emerged in clinical practice owing to the dry antibiotic development
pipeline and worldwide increasing prevalence of nosocomial infections caused by multidrug-resistant
(MDR) Gram-negative bacteria. Polymyxin B and colistin (polymyxin E) have been ultimately
considered as the last-resort treatment of such infections. Microbiological, pharmacokinetic,
pharmacodynamic and clinical data available for polymyxin B are reviewed in this paper.
Polymyxin B has rapid in vitro bactericidal activity against major MDR Gram-negative
bacteria, such as Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumoniae.
Acquired resistance to this agent is still rare among these pathogens. However, optimized
dosage regimens are not known yet. Good clinical outcomes have been observed in the
majority of the patients treated with intravenous polymyxin B in recent studies. However,
these studies failed to provide definitive conclusions due to limitations of study
design and additional clinical trials are required. Although combination therapy may
be an attractive option based on some currently available in vitro data, clinical
data supporting such recommendations are lacking. Since polymyxins will be increasingly
used for the treatment of infections caused by MDR bacteria, clinical pharmacokinetic,
pharmacodynamic and toxicodynamic studies underpinning the optimal use of these drugs
are urgently required.