Original Article STABILITY INDICATING LC–ESI-MS/MS METHOD DEVELOPMENT AND VALIDATION FOR THE QUANTITATION OF LURBINECTEDIN IN BIOLOGICAL MATRICES MANTRAVADI ANUSHA, RAMREDDY GODELA * , KUMAR SHIVA GUBBIYAPPA Department of Pharmaceutical Analysis, GITAM School of Pharmacy, GITAM Deemed to be Univeristy, Rudraram, Patancheru, Telangana, India * Corresponding author: Ramreddy Godela; * Email: rgodela@gitam.edu Received: 24 Dec 2024, Revised and Accepted: 11 Jun 2025 ABSTRACT Objective: A new and validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and used for the quantitative analysis of the anticancer drug Lurbinectedin in plasma samples. Methods: Liquid-liquid extraction method was used to extract the Lurbinectedin from plasma, and Ledipasvir was used as an internal standard (IS), Chromatographic separation of Lurbinectedin was accomplished with Zorbax SB-C18 column (250 mm×4.6 mm, 5 μm) using a mobile phase comprises of 0.1% v/v formic acid and acetonitrile (10:90, v/v) pumped at a flow rate of 0.80 ml/min. The total run time for Lurbinectedin and internal standard elution was 3.5 min. The linearity was attained for a concentration range of 1.50–5000 ng/ml with a correlation coefficient (r²) of 0.9994 by the optimized method. The lower limit of quantification (LLOQ) was established at 1.50 ng/ml, which resembles the sensitivity of the method toward Lurbinectedin. Results: The method showed high accuracy, ranging from 95.31% to 104.06% of nominal values, with intra-and inter-day precision within a 4.32% coefficient of variance (%CV). Matrix effects at the low-quality control (LQC) level varied between 94.25% and 104.85% (%CV: 4.61), while at the high-quality control (HQC) level, they ranged from 94.62% to 103.88% (%CV: 4.02). The mean recovery across all control standards was 95.58%. Conclusion: Stability assessments confirmed the robustness of the method. The developed LC-MS/MS approach is reliable for routine bioanalytical applications, including quality control, pharmacokinetic studies, and bioequivalence assessments of Lurbinectedin in biological matrices. Keywords: Lurbinectedin, LC-ESI-MS/MS, Bioanalytical method, Precision, Sensitivity, Zorbax SB-C18 column © 2025 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license (https://creativecommons.org/licenses/by/4.0/) DOI: https://dx.doi.org/10.22159/ijap.2025v17i5.53562 Journal homepage: https://innovareacademics.in/journals/index.php/ijap INTRODUCTION A DNA alkylating medication known as Lurbinectedin has been investigated for potential use in treating many cancers, including CLL (fig. 1), mesothelioma, breast cancer, and SCLC. The anticancer chemical Ecteinascidin (trabectedin) is derived from the marine tunicate Ecteinascidia turbinata. The primary change is that Lurbinectedin is more effective against tumors than trabectedin due to the substitution of a tetrahydro β‐carboline for tetrahydroisoquinoline [1]. As it binds to guanine residues in the DNA's minor groove, it generates adducts that cause the DNA helix to bend toward the major groove. A cascade of events begins at this step, altering the function of transcription factors and decreasing the efficacy of DNA repair pathways. Ultimately, this leads to cell death by breaking double-stranded DNA. It also inhibits RNA-polymerase-II activity, nucleotide transfer inhibits EWS-FL11 protein expression, and inhibits human monocyte activity and macrophage entrance into tumor tissue, among other mechanisms [2]. Strong DNA attachment is the mechanism by which Lurbinectedin exerts its chemotherapeutic action, causing DNA strand breakage and cell death [3]. Because Lurbinectedin has been associated with myelosuppression, patients using this medication should have cytopenias monitored carefully. Verify that the platelet count is more than 100,000/mm3 and the neutrophil count is greater than 1,500 cells/mm3 prior to beginning therapy. If the neutrophil count falls below 500 cells/mm3, it may be prudent to consider administering granulocyte colony-stimulating factor (G-CSF). Lurbinectedin has also been associated with liver damage. During and after therapy, it is important to monitor liver function tests. Delaying, reducing, or discontinuing treatment entirely may be necessary depending on the severity of the hepatotoxicity [4-6]. There are just two published protocols on LCMS/MS in the literature on Lurbinectedin [7, 8]. Nicholas et al. developed a method having a calibration curves displayed good linearity over 0.1 to 50 ng/ml for lurbinectedin and 0.5 to 20 ng/ml for the metabolites. This method has poor recovery results with a 12.9% error [7]. Andel et al. developed a method having linearity up to 100 ng/ml [8]. The method was linear over 0.1–100 ng/ml and 1–1000 ng/ml in plasma and urine, respectively, with accuracies and precisions within ±15% (20% for LLOQ) and below 15% (20% for LLOQ), respectively. The fields of pharmacodynamics, forensics, and pharmacokinetics studies require specific methods with good recovery values. Hence, there is a need for an LC-MS/MS approach to studying human K2 EDTA plasma. Fig. 1: Chemical structure of lurbinectedin MATERIALS AND METHODS Reagent chemicals Hetero Pharmaceuticals of Hyderabad, India, supplied the Ledipasvir (with a purity level of 99.52 percent). The drug Lurbinectedin was sourced from Selleck Chemicals in Houston, Texas, USA. Plasma from the Vivekananda Blood Bank in Hyderabad, India, which is devoid of drugs and contains the anticoagulant K2-EDTA, was obtained. The International Journal of Applied Pharmaceutics ISSN- 0975-7058 Vol 17, Issue 5, 2025