# Stability-indicating UPLC assay coupled with mass spectrometry for the analysis of vilanterol degradation products in human urine

## TL;DR

This study developed a method to analyze vilanterol and its breakdown products in human urine using advanced chromatography and mass spectrometry techniques.

## Contribution

A stability-indicating UPLC-MS method was developed for vilanterol degradation products in urine, crucial for anti-doping purposes.

## Key findings

- Vilanterol degrades under acidic, basic, and oxidative stress but remains stable under photolytic and thermal stress.
- Degradation followed first-order kinetics, with calculated K, t1/2, and t90 values.
- The method accurately quantified vilanterol and its metabolites in human urine within a relevant concentration range.

## Abstract

Vilanterol is a once-daily dose inhaler prescribed for asthma and chronic obstructive pulmonary disease. This study involved an investigation of vilanterol stability under acidic, basic, oxidative, thermal, and photolytic stress conditions. UPLC method was developed and validated for the analysis of vilanterol with its degradants. The drug was stable under photolytic and thermal stress conditions and degraded under acidic, basic, and oxidative stress conditions. Degradation kinetics was performed for acidic, basic and oxidative stress conditions. Kinetics parameters, K, half-life time (t1/2) and shelf-life time (t90) were assessed, and the degradation followed first order reaction. The method was linear from 0.10 to 100.00 µg mL−1 with accuracy, inter-day and intra-day precision from 99.45 to 100.02%, 0.391–0.694 and 0.041–0.345, respectively. Mass spectrometry was employed to elucidate the structure of the degradants, and the results revealed that certain degradation products were comparable to vilanterol metabolites. The World Anti-Doping Agency has prohibited the presence of vilanterol and its metabolites in athletes’ urine except for exercise bronchoconstriction with limited dose. So, quantification of vilanterol in the presence of its degradants was performed in human urine. The results revealed that the method was linear in range of 1.00 to 100.00 µg mL−1. Samples collection and experimental protocol was performed according to the guidelines of the Research Ethics Committee of the Faculty of Pharmacy, the British University in Egypt with approval No. CH-2305.