Method development and validation of Guanfacine in rat plasma by liquid chromatographyâtandem mass spectrometry: Application to a pharmacokinetic study

A selective, sensitive and high-throughput liquid chromatographyâtandem mass spectrometry (LCâESI-MS/MS) method has been developed and validated for the quantitation of Guanfacine in rat plasma. Sample clean-up involved liquidâliquid extraction (LLE) and 100 μL of rat plasma was used. YMC BASIC column (50 mmÃ2.0 mm, 3.5 µm) was used. Mobile phase used was 10 mM ammonium formate (pH 4.0):acetonitrile (70:30, v/v) at a flow rate of 0.3 mL/min. The parentâproduct ion transitions for the drug (m/z 246.0â159.0) and IS (m/z 252.0â161.1) were monitored on a triple quadrupole mass spectrometer, operating in the multiple reaction monitoring (MRM) and positive ion mode. The method was validated over the concentration range of 50.00â10,000.00 pg/mL for Guanfacine. The method was successfully applied into a pharmacokinetic study in rat plasma. Keywords: Guanfacine, LCâESI-MS/MS, Rat plasma, Liquidâliquid extraction, Pharmacokinetic study