Global Advanced Research Journal of Medicine and Medical Sciences (ISSN: 2315-5159) Vol. 5(2) pp. 042-052, February, 2016 Available online http://garj.org/garjmms Copyright © 2016 Global Advanced Research Journals Full Length Research Paper Optimized HILIC-MS/MS Method for Simultaneous Determination of two Antiepileptic Drugs with Significant Difference in Binding to Serum Albumin Hassan A. Alhazmi 1* , Mohammed Al Bratty 1 , Gunasekar Manoharan 1 , Hafiz A. Makeen 2 and Adnan A. Kadi 3 1 Jazan University, College of pharmacy, Department of Pharmaceutical Chemistry, P.O. Box 114, Jazan 45142, Saudi Arabia. 2 Jazan University, College of pharmacy, Department of Clinical Pharmacy, P.O. Box 114, Jazan 45142, Saudi Arabia. 3 King Saud University, College of pharmacy, Department of Pharmaceutical Chemistry, P.O. Box 2457, Riyadh 11451, Saudi Arabia. Accepted 04 February, 2016 Different HILIC columns were studied and compared. Each column showed different behaviors regarding to the separation of four antiepileptic drugs and the influence on MS/MS sensitivity through the ionization of the drugs. HILIC Luna was selected since it has been offered good separation and sensitivity. Additionally, a fast, sensitive and selective HILIC-MS/MS method was developed for the detection and quantification of two antiepileptic drugs, carbamazepine (highly bind to serum albumin) and vigabatrin (not significant bind to serum albumin) in human plasma. Samples were purified by two steps, precipitation by methanol and using the supernatant for vigabatrin and liquid–liquid extraction using ethylacetate for carbamazepine. The separation was successfully achieved on a HILIC LUNA 3μm (2× 150 mm) column with a mobile phase consisting acetonitril/ammonium formate (5mM, pH 3.5) (75:25, v/v). A triple quadrupole model G6410A mass spectrometerin the MRM mode was used for detection using electro spray ionisation (ESI). The detections were based on the transition of the protonated molecular ion for carbamazepine at m/z 237 and vigabatrin at m/z 130 to the predominant ions of m/z 194 and 71, respectively. The acceptable mean recoveries were 81% for carbamazepine and 100% for vigabatrin. Furthermore, the calibration curves were linear over the concentration range 250–8000 ng/mL for carbamazepine and 15–960 ng/ml for Vigabatrin. The LODs for carbamazepine and vigabatrin in human plasma were 5.43 ng/mL and 3 ng/mL, respectively. Keywords: HILIC, MS/MS, Carbamazepine, Vigabatrin. INTRODUCTION Therapeutic drug monitoring (TDM) of antiepileptic drugs *Corresponding Author E-Mail: hasalhazmi@gmail.com; Phone: +966 541433344 is always important to optimize the acceptable therapeutic level of the antiepileptic dugs in plasma including carbamazepine (CBZ) and vigabatrin (VGB) (Gross, 1998;Maresova et al., 2008). CBZ is an established drug for the control of grand mal and psychomotor epilepsy and is also effective in the