Development and Validation of an HPLC-UV Detection Assay for the Determination of Clonidine in Mouse Plasma and Its Application to a Pharmacokinetic Study.

An accurate and simple HPLC-UV method has been developed for the determination of clonidine in mouse plasma. A reversed phase C18 Nova Pack ^® column (125 mm × 4.6 mm i.d., × 3 μm particle size) was used as stationary phase. The mobile phase composition was a mixture of 0.1% diethylamine/acetonitrile (70:30, v / v ) at pH 8 in an isocratic mode at flow rate was 1.0 mL/min. Detection was set at 210 nm. Tizanidine was used as an internal standard. The clonidine and tizanidine were extracted from plasma matrix using the deproteinization technique. The developed method exhibited a linear calibration range 100.0-2000 ng/mL and the lower limit of detection (LOD) and quantification (LOQ) were 31.0 and 91.9 ng/mL, respectively. The intra-day and inter-day accuracy and precision of the method were within 8.0% and 3.0%, respectively, relative to the nominal concentration. The developed method was validated with respect to linearity, accuracy, precision, and selectivity according to the US Food and drug guideline. Minimal degradation was demonstrated during the determination of clonidine under different stability conditions. The suggested method has been successfully applied during a pharmacokinetic study of clonidine in mouse plasma.