Precision and Accuracy in the Quantitative Analysis of Biological Samples by Accelerator Mass Spectrometry: Application in Microdose Absolute Bioavailability Studies

Abstract

Determination of the pharmacokinetics and absolute bioavailability of an experimental compound, SCH 900518, following a 89.7 nCi (100 μg) intravenous (iv) dose of 14C-SCH 900518 2 h post 200 mg oral administration of nonradiolabeled SCH 900518 to six healthy male subjects has been described. The plasma concentration of SCH 900518 was measured using a validated LC–MS/MS system, and accelerator mass spectrometry (AMS) was used for quantitative plasma 14C-SCH 900518 concentration determination. Calibration standards and quality controls were included for every batch of sample analysis by AMS to ensure acceptable quality of the assay. Plasma 14C-SCH 900518 concentrations were derived from the regression function established from the calibration standards, rather than directly from isotopic ratios from AMS measurement. The precision and accuracy of quality controls and calibration standards met the requirements of bioanalytical guidance (U.S. Department of Health and Human Services, Food and Drug Administration, Center for Drug Evaluation and Research, Center for Veterinary Medicine. Guidance for Industry: Bioanalytical Method Validation (ucm070107), May 2001. ). The AMS measurement had a linear response range from 0.0159 to 9.07 dpm/mL for plasma 14C-SCH 900158 concentrations. The CV and accuracy were 3.4–8.5% and 94–108% (82–119% for the lower limit of quantitation (LLOQ)), respectively, with a correlation coefficient of 0.9998. The absolute bioavailability was calculated from the dose-normalized area under the curve of iv and oral doses after the plasma concentrations were plotted vs the sampling time post oral dose. The mean absolute bioavailability of SCH 900518 was 40.8% (range 16.8–60.6%). The typical accuracy and standard deviation in AMS quantitative analysis of drugs from human plasma samples have been reported for the first time, and the impact of these parameters on quantitative analysis was further assessed using the Z factor. The use of the lowest achievable LLOQ Z =0 derived from statistical analysis of the control and low-concentration standards for AMS measurements is proposed in future studies.

Optimization and Validation of a Reverse-Phase High Performance Liquid Chromatography Assay with Ultra-Violet Detection for Measuring Total L-Ascorbic Acid in Food and Beverage Products

“…The results show that all parameters evaluated fell within their respective limits. The precision, expressed as the coefficient of variation (COV) of the retention time (0.018) was less than 1% and is in keeping with the FDA's acceptance limit [21]. The precision of the response (COV=1.470) fell within 2% and is in compliance with the United States Pharmacopeia (USP) requirements [46].…”

“…Parallel lines are constructed at 95% and 105% of the horizontal relative response line and the intersection points illustrate where the method is nonlinear [13]. In the latter approach, the peak absorbance areas were plotted against the L-AA concentrations (µg/mL) and the results were assessed using least squares linear regression [21]. Subsequently five samples (camu powder extract, dragonfruit flavoured vitamin water, orange flavoured vitamin water, pressed berry and tropical juices) were appropriately diluted at four different concentrations within the linear standard calibration range.…”

“…The precision of the assay was evaluated by intermediate precision, intra-assay precision and repeatability of injection [21]. Intermediate precision was performed by assaying three L-AA standards (10, 50 and 125 µg/mL) in triplicate over three separate days.…”

“…System suitability parameters such as capacity factor, number of theoretical plates, resolution, peak asymmetry factor and selectivity were determined in accordance with the FDA: Reviewer Guidance [21]. A tomato extract sample (3 µg/mL L-AA) was injected five times and the results were evaluated for system suitability according the acceptance criteria set out in the FDA/CDER: Reviewer Guidance.…”

Quantification of Antifungal Drug Voriconazole in Serum and Plasma by HPLC-UV

“…The validated linearity up to 10 µg/mL for the method described here makes this method applicable across the wide range of serum concentrations found for patients receiving voriconazole. The current method validation was based on the Guidance for Industry Bioanalytical Method Validation [46] published by the Food and Drug Administration. The current method met all the requirements for developing a calibration curve.…”