A liquid chromatography-tandem mass spectrometry method development for the quantification of favipiravir drug and its related impurities in rat plasma and its application to pharmacokinetic studies.

Favipiravir is an antiviral drug used for the treatment of virus-based diseases such as influenza. In this context, the development of a reliable liquid chromatography-tandem mass spectrometry method for the quantification of the drug and its impurities is necessary, particularly following the COVID-19 pandemic. Chromatographic separation was achieved on an inertial ODS column using gradient elution with a buffer containing triethylamine in high-performance liquid chromatography water and adjusting its pH with formic acid. The mixture of buffer and acetonitrile was used as a mobile phase with a flow rate of 1 ml/min at ambient temperature. The separation of favipiravir and its related impurities from remdesivir as an internal standard was achieved. The results indicated that all the variables, like precision, accuracy, linearity, matrix effect and stability, were successfully achieved within the limits of US Food and Drug Administration guidelines. This study could provide a new protocol for the development of new analytical methods for the detection of favipiravir and its impurities.

Development of an efficient stability-indicating LC-MS/MS method for the analysis of selexipag and characterization of its degradation products.

A new RP-HPLC method with a quick, sensitive and stable indication for the quantitative measurement of selexipag and its associated substances was developed and validated in the present study. In this new method, using the impurity-spiked solution, the chromatographic approach was optimized. Similarly, using the X-bridge phenyl column with isocratic elution of mobile phase containing acetonitrile and formic acid, selexipag and its impurities were separated. Recovery experiments obtained were satisfactory, and also the calibration graphs plotted for selexipag and its five impurities were found to be linear. The system validation parameters such as specificity, linearity, precision, accuracy and robustness were determined successfully. The obtained results indicated that the developed method was found to be useful for analyzing selexipag from its impurities. Further, using stress tests against acid, alkali, peroxide, reduction, thermal, hydrolysis and UV conditions, the present established method of HPLC was assessed and validated as per ICH Q2(R1) guidelines.