507BIOANALYTICAL METHOD DEVELOPMENT AND VALIDATION OF ESZOPICLONE IN RABBIT PLASMA BY HPLC-MS/MS AND ITS APPLICATION TO PHARMACOKINETIC STUDYAuthors developed a simple, sensitive, selective, rapid, rugged and reproducible liquid chromatography–tandem mass spectrometry method for the quantification of Eszopiclone (EP) in Rabbit plasma using Eszopiclone D8 (EPIS) as an internal standard (IS). Chromatographic separation was performed on Ascentis express CN 50X4.6 mm, 2.7 µm column. Mobile phase composed of 15 mM Ammonium formate: methanol (15:85 v/v), with 0.6 mL/min flow-rate. Drug and IS were extracted by Liquid- liquid extraction. EP and EPIS were detected with proton adducts at m/z 389.1245.2 and 397.1245.2 in multiple reaction monitoring (MRM) positive mode respectively. The method was validated with the correlation coefficients of (r2) ≥ 0.9850 over a linear concentration range of 0.05-210.0 ng/mL. This method demonstrated intra and inter-day precision within 2.12 to 7.07 and 1.50 to 5.73 % and accuracy within 99.29 to 102.00 and 100.00 to 102.21 % for EP. This method is successfully applied in the Pharmacokinetic study of 6 healthy Rabbitsbaluchalla_99@yahoo.comResearch592014Liquid chromatography,Mass spectrometry,Eszopiclone,Rabbit plasma,PharmacokineticsS. Kumar.Moola,Bala Sekhara Reddy.Challa,K.B.ChandrasekharARPL Pvt. Ltd, Bangalore -560099, Karnataka, India,Vagdevi College of Pharmacy, Gurazala -522 415, Andhra Pradesh, India,Jawaharlal Nehru Technological University Anantapur, Anantapur -522001, Andhra Pradesh, India