Determination of antimalarial compound, ARB-89 (7β-hydroxy-artemisinin carbamate) in rat serum by UPLC/MS/MS and its application in pharmacokinetics

Among all the antimalarial agents, artemisinin and its semi synthetic family of analogs are the most potent antimalarials available for the treatment of Plasmodium falciparum infections. But these analogs have a few issues such as shorter half-lives and low oral bioavailability values. In order to overcome these inherent problems, novel artemisinin analogs were synthesized from 7β-hydroxy artemisinin by the Department of Medicinal Chemistry, University of Mississippi using a new synthesis mechanism. Out of all the 7β-hydroxy artemisinin analogs synthesized, 7β-hydroxy artemisinin carbamate (ARB-89) was chosen as a lead compound because of its high in vitro and in vivo activity. In this manuscript, a sensitive and rapid ultra-performance liquid chromatography tandem mass spectrometry (UPLC/MS/MS) method was developed and validated for the quantification of ARB-89 in rat serum. The analysis was carried out on an Acquity™ UPLC BEH C18 column (1.7 μm, 2.1 mm × 50 mm) with a flow rate of 0.3 mL/min. The detection was performed on a triple quadrupole tandem mass spectrometer in positive electrospray ionization (ESI) mode. The selected mass-to-charge (m/z) ratio transitions used in the multiple reaction monitoring (MRM) for ARB-89 and artemisinin (internal standard) were m/z 778.4 > 253.4 and m/z 283.4 > 151.1 respectively. The calibration curve was linear from 1.00 ng/mL to 10.0 μg/mL (r2 = 0.999). A simple protein precipitation method was used for extraction. Moreover, the inter-day and intra-day precision values were found to be less than 15%. The recoveries of the method ranged from 94.0% to 96.7% at three concentrations. ARB-89 in rat serum was found to be stable at room temperature for 12 h. This method was successfully used to quantitate the novel antimalarial compound ARB-89 after intravenous and oral administration to rats.