_____________________________________________________________________________________________________ *Corresponding author: E-mail: senem.sanli@usak.edu.tr; Journal of Pharmaceutical Research International 33(40B): 261-266, 2021; Article no.JPRI.70681 ISSN: 2456-9119 (Past name: British Journal of Pharmaceutical Research, Past ISSN: 2231-2919, NLM ID: 101631759) A Simple LC-MS/MS Method for Determination of Vemurafenib in Rat Plasma Fed with High Fat Diet Ayşe Özdemir 1 , Senem Şanli 2* and Erten Akbel 3 1 Division of Biochemistry, School of Medicine, Uşak University, Uşak, Turkey. 2 Department of Chemistry, Faculty of Science and Arts, Uşak University, Uşak, Turkey. 3 Department Physiotherapy and Rehabilitation, Faculty of Health Sciences, Uşak University, Uşak, Turkey. Authors’ contributions This work was carried out in collaboration among all authors. All authors read and approved the final manuscript. Article Information DOI: 10.9734/JPRI/2021/v33i40B32285 Editor(s): (1) Dr. Dharmesh Chandra Sharma, G. R. Medical College & J. A. Hospital, India. Reviewers: (1) Hamza Ahmed Pantami, Gombe State University, Nigeria. (2) Zhipeng Li, Guangxi University, China. (3) Younus Khudhur, Kirkuk University, Iraq. Complete Peer review History: https://www.sdiarticle4.com/review-history/70681 Received 25 May 2021 Accepted 30 July 2021 Published 12 August 2021 ABSTRACT In this study, high fat diet was fed to rats and the amount of vemurafenib in rat plasma was determined by the developed liquid chromatography with tandem mass spectrometry. The calibration curve was linear between 0.01 and 0.8 µg mL −1 vemurafenib with 0.999 regression coefficient. The limit of detection and quantification of the method are estimated from the signal to noise ratio 3:1 and 10:1, respectively. These are 1.10 -4 µg mL −1 for LOD and 4. 10 -4 µg mL −1 for LOQ. This method has been found to be reproducible and highly sensitive and provides a combination of faster analysis time and improved limits of detection. Keywords: Vemurafenib; rat plasma; LC-MS/MS; fat diet. 1. INTRODUCTION Vemurafenib (VEM, Fig. 1) is the first selective, potent and orally bioavailable inhibitor of the serine/threonine-protein kinase b-raf protein encoded by the V600E mutated braf gene [1]. Vemurafenib was recently approved by authorized agencies for the treatment of Original Research Article