Liquid chromatography-electrospray quadrupole linear ion trap mass spectrometry method for the quantitation of palonosetron in human plasma and urine: Application to a pharmacokinetic study.

The new analytical method for the determination of palonosetron in human plasma and urine has been developed based on liquid chromatography-mass spectrometry. The method utilized tramadol as the internal standard (IS). Separation was carried out on a Zorbax Eclipse TC-C(18) column using methanol-1mM ammonium formate in water (containing 0.1% formic acid, v/v, pH=2.8) as mobile phase for gradient elution. Detection is carried out by multiple reaction monitoring (MRM) on 3200 Qtrap mass spectrometry. The method has a chromatographic run time of 5.5 min and is linear within the concentration range 0.01-5.00 ng/mL for plasma and 0.10-30.00 ng/mL for urine both with a LOD of 0.003 ng/mL. Intra- and inter-day RSD of the concentration was 3.66-6.60%, 1.29-7.71% for plasma and 2.39-5.76%, 2.06-7.13% for urine. The relative error (RE) was -4.58% to 3.26% for plasma and -1.47% to 2.53% for urine. The recovery rates of palonosetron and IS both for plasma and urine were more than 90%. Palonosetron was stable under all the conditions tested. The method was successfully used to analyze palonosetron in human plasma and urine over a period of 168 h after intravenously pumping a single dose of 0.25mg to volunteers. No significant differences were found between the pharmacokinetic parameters and urine accumulated excretory rate for male and female volunteers (P>0.05). A two-compartment model was obtained after administrations. Palonosetron was eliminated at a slow rate in volunteers. The mean urine accumulated excretory rate was 25.97 ± 12.87%. Inter-individual differences could not be neglected due to the high coefficient of variety in several pharmacokinetic parameters and the urine accumulated excretion.