Development and Validation of a High-Performance Liquid Chromatography with Tandem Mass Spectrometry (HPLC-MS/MS) Method for Quantification of Major Molnupiravir Metabolite (β-D-N4-hydroxycytidine) in Human Plasma.

Molnupiravir is an antiviral drug against viral RNA polymerase activity approved by the FDA for the treatment of COVID-19, which is metabolized to β-D-N4-hydroxycytidine (NHC) in human blood plasma. A novel method was developed and validated for quantifying NHC in human plasma within the analytical range of 10-10,000 ng/mL using high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) to support pharmacokinetics studies. For sample preparation, the method of protein precipitation by acetonitrile was used, with promethazine as an internal standard.

[Chromogranin A in diagnosis of pheochromocytoma (comparative analysis)].

Aim: To study the prognostic value of determining Chromogranin A blood level in the diagnosis of PHEO.

Materials And Methods: We conducted a comparative analytical study of 157 patients with suspected PHEO, statistical analysis of 24-hour urinary metanephrine and normetanephrine excretion test was performed, as well as a blood test for CrA, in groups that included patients without PHEO, with primary tumor or its recurrence, confirmed according to MSCT and/or scintigraphy with MIBG and/or the clonidine suppression test.

Results: The parameters of efficiency of these methods were calculated by groups and it was noted that the lowest sensitivity of the CrA determination method was observed in the group with recurrence of PHEO (43.