ABSTRACT
An improved LC-MS/MS method for the quantitation of indapamide in human whole blood was developed and validated. Indapamide-d3 was used as internal standard (IS) and liquid-liquid extraction was employed for sample preparation. LC separation was performed on Synergi Polar RP-column (50 × 4.6 mm i.d.; 4 µm) and mobile phase composed of methanol and 5 mm aqueous ammonium acetate containing 1 mm formic acid (60:40), at flow rate of 1 mL/min. The run time was 3.0 min and the injection volume was 20 µL. Mass spectrometric detection was performed using electrospray ion source in negative ionization mode, using the transitions m/z 364.0 â m/z 188.9 and m/z 367.0 â m/z 188.9 for indapamide and IS, respectively. Calibration curve was constructed over the range 0.25-50 ng/mL. The method was precise and accurate, and provided recovery rates >80% for indapamide and IS. The method was applied to determine blood concentrations of indapamide in a bioequivalence study with two sustained release tablet formulations. The 90% confidence interval for the geometric mean ratios for maximum concentration was 95.78% and for the area under the concentration-time curve it was 97.91%. The tested indapamide tablets (Eurofarma Laboratórios S.A.) were bioequivalent to Natrilix®, according to the rate and extent of absorption.
Subject(s)
Chromatography, Liquid/methods , Indapamide/blood , Indapamide/pharmacokinetics , Tandem Mass Spectrometry/methods , Adolescent , Adult , Humans , Indapamide/chemistry , Male , Middle Aged , Reproducibility of Results , Sensitivity and Specificity , Spectrometry, Mass, Electrospray Ionization , Therapeutic Equivalency , Young AdultABSTRACT
A liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) method for the simultaneous quantitation of artemether and lumefantrine in human plasma was developed and validated. Artesunate was used as an internal standard (IS). The analytes were extracted by a protein precipitation procedure and separated on a reversed-phase Zorbax SB-Ciano column with a mobile phase composed of methanol and 10mM aqueous ammonium acetate containing 0.2% (v/v) acetic acid and 0.1% (v/v) formic acid. Multiple reaction monitoring was performed using the transitions m/z 316 â m/z 267, m/z 530 â m/z 348 and m/z 402 â m/z 267 to quantify artemether, lumefantrine and artesunate, respectively. Calibration curves were constructed over the range of 10-1000 ng/mL for artemether and 10-18,000 ng/mL for lumefantrine. The lower limit of quantitation was 10 ng/mL for both drugs. The mean R.S.D. values for the intra-run precision were 2.6% and 3.0% and for the inter-run precision were 3.6% and 4.6% for artemether and lumefantrine, respectively. The mean accuracy values were 102.0% and 101.2% for artemether and lumefantrine, respectively. No matrix effect was detected in the samples. The validated method was successfully applied to determine the plasma concentrations of artemether and lumefantrine in healthy volunteers, in a one-dose pharmacokinetic study, over the course of 11 days.
