New rifamycins for the treatment of bacterial infections

This review summarizes patent disclosures from the period 2003-2006 that claim novel rifamycin derivatives for antibacterial, antimicrobial or other chemotherapeutic uses. Modification of the rifamycin skeleton has led to several series of new derivatives with the potential to expand the clinical utility of rifamycins beyond the treatment of mycobacterial infections. The key liabilities of the existing approved rifamycins are drug-drug interactions mediated through their activity as inducers of cytochrome P450 enzymes, and the relatively high rate of resistance development that arises during clinical use. Several patents describe compounds that seem to have addressed one or both of these liabilities.