Abstract

DEVELOPMENT AND VALIDATION OF A LC-MS/MS METHOD FOR THE DETERMINATION OF LETERMOVIR IN SPRAGUE DAWLEY RAT PLASMA AND ITS APPLICATION TO PHARMACOKINETIC STUDY

K. N. Rajanikanth, Dr. V. Kiran Kumar, Dr. VVSS. Appala Raju, Dr. Macharla Venkata Ramana, Dr. T. Shyam and Dr. N. Appala Raju*

ABSTRACT

During the preclinical study of the new antiviral drug, Letermovir, a sensitive liquid chromatography tandem mass spectrometry method was newly developed to study the pharmacokinetics of Letermovir in rat plasma and subcutaneous tissue samples. Although Letermovir was unstable in the rat plasma and subcutaneous tissue samples, pretreatment with EDTA and phosphoric acid (4 %) inhibited its degradation. The lower limits of quantification (LLOQ) for Letermovir were fully validated as 5 ng/ml in plasma and 5 ng/g in tissue with acceptable linearity, intra- and inter-assay precisions, and accuracy. Measurement of Letermovir concentration in plasma after intravenous injection via LC-MS/MS yields plasma concentration-time curves (AUC 0-∞) with areas of 667 ng•min/ml and an elimination half-life (t1/2) of 4.8 min. The concentration of Letermovir in the subcutaneous tissue samples was 13.1 μg/gm tissues at 30 minutes after a single dermal application (1 mg/ml, 50 μl) to a full-thickness excisional wound. Here, a highly sensitive and specific LC-MS/MS assay with a lower limit of quantification of 5 ng/ml was developed and validated to quantify Letermovir in rat plasma. This method is useful for pharmacokinetic studies of the peptide drugs in rats.

Keywords: LC-MS/MS, Pharmacokinetics, Plasma, Quantitation, Subcutaneous Tissue.