Simultaneous determination of bendamustine and its active metabolite, gamma-hydroxy-bendamustine in human plasma and urine using HPLC-fluorescence detector: application to a pharmacokinetic study in Chinese cancer patients.

A simple, sensitive and cost-effective assay based on reversed phase high performance liquid chromatography (RP-HPLC) with isocratic mode for simultaneous determination of bendamustine (BM) and its active metabolite, gamma-hydroxy-bendamustine (γ-OH-BM) in human plasma and urine was developed and validated. Sample preparation involved protein precipitation by 10% perchloric acid-methanol solution. The peaks were recorded by using fluorescence detector (excitation wavelength 328 nm and emission wavelength 420 nm). The calibration curves were linear over concentration ranges of 8.192-10,000 ng mL(-1) and 5-1,000 ng mL(-1) for BM in human plasma and urine as well as 10-1,000 ng mL(-1) and 5-1,000 ng mL(-1) for γ-OH-BM in human plasma and urine, respectively. Intra- and inter-run precisions of BM and γ-OH-BM were less than 15% and the bias were within ± 15% for both plasma and urine. This validated method was successfully applied to a pharmacokinetic study enrolling 10 Chinese patients with indolent B-cell non-Hodgkin lymphoma and chronic lymphocytic leukemia administered a single intravenous infusion of 100 mg m(2) bendamustine hydrochloride.