Development and validation of a simple, sensitive and accurate LC‐MS/MS method for the determination of guanfacine, a selective α_2A‐adrenergicreceptor agonist, in plasma and its application to a pharmacokinetic study

Abstract

A simple, practical, accurate and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and fully validated for the quantitation of guanfacine in beagle dog plasma. After protein precipitation by acetonitrile, the analytes were separated on a C18 chromatographic column by methanol and water containing 0.1% (v/v) formic acid with a gradient elution. The subsequent detection utilized a mass spectrometry under positive ion mode with multiple reaction monitoring of guanfacine and enalaprilat (internal standard) at m/z 246.2 → 159.0 and m/z 349.2 → 205.9, respectively. Good linearity was obtained over the concentration range of 0.1-20 ng/mL for guanfacine in dog plasma and the lower limit of quantification of this method was 0.1 ng/mL. The intra- and inter-day precisions were <10.8% relative standard deviation with an accuracy of 92.9-108.4%. The matrix effects ranged from 89.4 to 100.7% and extraction recoveries were >90%. Stability studies showed that both analytes were stable during sample preparation and analysis. The established method was successfully applied to an in vivo pharmacokinetic study in beagle dogs after a single oral dose of 4 mg guanfacine extended-release tablets.

Determination of Guanfacine in Oral Fluid and Serum of Children and Adolescents with Attention-Deficit/Hyperactivity Disorder: A Short Communication

“…After thawing, oral fluid and serum samples were deproteinized and guanfacine was analyzed using a modified liquid chromatography-tandem mass spectrometry (LC-MS/ MS) method as previously reported in detail. 19 To simplify sample preparation and reduce the processing time for routine use, the following modifications were applied to the sample treatment.…”