An update on repurposed medications for the treatment of drug-resistant tuberculosis.

INTRODUCTION: Drug-resistant forms of tuberculosis are a major public health problem with a serious global impact. Although there have recently been two new drugs introduced for the treatment of drug-resistant TB (bedaquiline and delamanid), the current therapeutic armamentarium is limited. Because treatment of drug-resistant TB requires the use of a multidrug-regimen, there has been growing interest in the use of antibiotics developed for other infectious pathogens but that have shown efficacy in the treatment of TB. Areas covered: This paper will review these 're-purposed' agents - including the beta-lactams, clarithromycin, clofazimine, the fluoroquinolones, and linezolid - with a focus on their efficacy, safety, and pharmacokinetic properties. Expert commentary: There is growing evidence on the efficacy and safety of repurposed drugs for the treatment of drug-resistant TB, supporting their program-wide inclusion in treatment regimens as recommended in revised WHO guidelines. However, additional work is needed to define optimum dosing as well as describe their role in regimen optimization.