# Study of Bitespiramycin Distribution in Rats and Cerebrospinal Fluid of Patients by a Sensitive LC-MS/MS Method with Rapid Sample Preparation

## TL;DR

A new method tracks where the drug bitespiramycin goes in rat bodies and human cerebrospinal fluid, showing it reaches the brain and other organs.

## Contribution

A sensitive and rapid UPLC–MS/MS method was developed for the first-time quantification of bitespiramycin in rat tissues and human cerebrospinal fluid.

## Key findings

- Bitespiramycin and its metabolites were detected in rat brain, testis, bladder, and prostate.
- The drug was also identified in human cerebrospinal fluid for the first time.
- The method avoids time-consuming steps and improves upon existing analytical techniques.

## Abstract

Bitespiramycin, has been shown to have a therapeutic effect against respiratory tract inflammation, including a potential effect against COVID-19. A current clinical trial in China showed that bitespiramycin was an effective treatment for severe pneumonia and intracranial infection. However, there is lack of an analytical method to elucidate the distribution of bitespiramycin. In this study, a highly sensitive, rapid and reliable UPLC–MS/MS method was developed to comprehensively characterize the bitespiramycin distribution in various bio-samples, which is significantly improved upon the published work. A rapid sample preparation method was developed by using n-butanol as the solvent to extract bitespiramycin from different bio-samples. The extract was then directly analyzed by UPLC–MS/MS coupled with an alkaline-resistant column after centrifugation which avoids the time-consuming concentration process under nitrogen and redissolution. The method was employed to accurately quantify bitespiramycin and its metabolites in rat plasma, tissues, and human cerebrospinal fluid. Notably, the presence of bitespiramycin and its metabolites was identified for the first time in various rat organs including brain, testis, bladder and prostate as well as in human cerebrospinal fluid. This newly developed approach shows great promise for drug distribution assays including other antibiotics and can help elucidate the ADME of bitespiramycin.