ABSTRACT
BACKGROUND: Lenalidomide (LND) is a new potent drug used for treatment of multiple myeloma. For its pharmacokinetic studies and therapeutic monitoring, a proper analytical method was required. RESULTS: In this study, a non extractive and simple pre-column derivatization procedures have been proposed, for the for trace determination of lenalidomide (LND) in human plasma by HPLC with fluorescence detection. Plasma samples were treated with acetonitrile for protein precipitation then treated with copper acetate to form stable complexes with the biogenic amines and mask their interference with the derivatization reaction of LND. Treated plasma samples containing LND was derivatized with fluorescamine (FLC) in aqueous media at ambient temperature. Separation of the derivatized LND was performed on Hypersil BDS C18 column (250 × 4.6 mm, 5 µm particle size) using a mobile phase consisting of phosphate buffer (pH 4):methanol: tetrahydrofuran (70:10:20, v/v) at a flow rate of 1.0 mL/min. The derivatized samples were monitored at an emission wavelength of 495 nm after excitation at a wavelength of 382 nm. Under the optimum chromatographic conditions, a linear relationship with good correlation coefficient (r = 0.9997, n = 9) was found between the peak area and LND concentrations in the range of 2-100 ng/mL. The limits of detection and quantitation were 0.8 and 2.30 ng/mL, respectively. The intra- and inter-assay precisions were satisfactory and the accuracy of the method was proved. The recovery of LND from the spiked human plasma was 99.30 ± 2.88. CONCLUSIONS: The proposed method had high throughput as the analysis involved simple sample pre-treatment procedure and a relatively short run-time (< 15 min). The results demonstrated that the method would have a great value when it is applied in the therapeutic monitoring and pharmacokinetic studies for LND.
ABSTRACT
Generic simple and sensitive universal enzyme immunoassay approach for the determination of small analytes has been developed to avert the problems associated with small molecule immobilization onto solid phases. The developed assay employed a heterogeneous non-competitive binding format. The assay used anti-analyte antibody coupled to polyacrylamide beads as a solid-phase and beta-d-galactosidase enzyme-labeled analyte as a label. In this assay, the analyte in a sample was firstly incubated to react with an excess of the antibody-coupled beads, and then the unoccupied antibody binding sites were allowed to react with the enzyme-labeled analyte. Analyte bound to the antibody-coupled beads was separated by centrifugation, and the enzyme activity of the supernatant was measured spectrophotometrically at 420nm, after reaction with 4-nitrophenyl-beta-d-galactopyranoside as a substrate for the enzyme. The signal was directly proportional to the concentration of analyte in the sample. The optimum conditions for the developed assay were established and applied to the determination of tobramycin, as a representative example of the small analytes, in serum samples. The assay limit of detection was 10ngmL(-1) and the effective working range at relative standard deviation of
ABSTRACT
The anodic polarographic behaviour of josamycin (a macrolide antibiotic) has been studied using direct current (DC(t)) polarography and differential pulse polarography (DPP). In Britton-Robinson buffers (BRb) josamycin exhibited well-defined anodic polarographic waves in the pH range 2-8. In BRb of pH 6, the diffusion-current constant was 1.62 microA mmol(-1) (n = 6). The current-concentration plots are rectilinear over the range 10-50 and 5-40 microg/ml using the DC(t) and DPP modes, respectively, with a detection limit of 4.83 x 10(-6) M adopting the DPP mode. The method was applied to commercial tablets adopting both DC(t) and DPP modes, the recoveries % were 99.13 +/- 2.22 (n = 10) and 99.82 +/- 1.82 (n = 7), respectively. The method was further extended to the in vitro determination of josamycin in human urine, the recovery % (n = 6) was 100.06 +/- 2.84. The number of electrons involved in the electrode process could be accomplished and a proposal of electrode reaction was presented.
