B-191 Development of a Simple, Robust, and Accurate LC-MS/MS Method for the Quantification of 17 Therapeutic Drugs: Initial Validation Results

Abstract

Abstract Background Therapeutic Drug Monitoring (TDM) of Zonisamide (ZON), Felbamate (FELB), Lamotrigine (LMTR), 10-Hydroxycarbamazipine (OXCARB), Carbamazepine Epoxide (CARBEP), and Pentobarbital (PENTO) is essential in developing the regimen to produce the best clinical outcomes while monitoring for possible toxicity. Historically, both HPLC-UV and LC-MS/MS have been used for the quantification of these types of drugs. HPLC-UV is often subject to interferences and extended run times. Because of this, there has been a shift to LC-MS/MS methods which are often simple, fast, robust, and suffer from less interferences. Our objective was to develop a simple, robust, and accurate LC-MS/MS method to replace the HPLC-UV methodology. Method Serum (50 µL) and IS solution (100 µL; Zonisamide-13C6, Lamotrigine-13C,15N4, (±)-10,11-Dihydro-10-hychoxycarbamazepine-13C6, Carbamazepine-10,11-epoxide-13C6, Felbamate-D4, Pentobarbital-D5 in methanol with 0.5% acetic acid) were vortex mixed and centrifuged. Supernatant (50 µL) was mixed with 950 µL of water and vortexed mixed. Extract was injected on a Thermo Accucore C18 column. A quantifier and qualifier transition was monitored for all analytes. Multiple Reaction Monitoring (MRM) was performed in positive mode for all analytes except for PENTO (negative). Total chromatographic time for the 17 analytes is 7.31 min. Results No ion suppression, differential matrix effect, or interferences were observed. Analytical Measurement Range (AMR) data for the initial 6 analytes is presented in Table 1. The coefficient of variation (%CV) was <2.8% for ZON, <4.3% for FELB, <7.3% for LMTR, <3.8% for OXCARB, <3.0% for CARBEP, and <3.5% for PENTO. Method comparison with a previously validated method were acceptable (Table 1). Conclusion This simple, robust, and accurate LC-MS/MS method has been validated for the initial 6 anlytes and has been determined to be acceptable for clinical use. Validation of the remaining 11 analytes is ongoing (Pregabalin, Gabapentin, Levetiracetam, Ethosuximide, Lacosamide, Rufinamide, Primidone, Lamotrigine, Topiramate, Brivaracetam, and Perampanel).