Clinical Bioanalysis Research Articles

Efficient and practical syntheses of a stable labelled form of the non‐narcotic analgesic, bicifadine and its metabolites

AbstractAn efficient and practical synthesis of deuterium‐labelled bicifadine, together with 3 deuterium‐labelled bicifadine metabolites, was developed. The levels of deuterium incorporation are high, and the products were used as internal standards in bioanalytical method development and clinical bioanalysis. Copyright © 2007 John Wiley & Sons, Ltd.

Recent advances in use of LC/MS/MS for quantitative high-throughput bioanalytical support of drug discovery.

LC/MS/MS based bioanalysis using atmospheric pressure ionization (API)-style interfaces has now been applied for over a decade. This technology, which initially found application for clinical bioanalysis, is now firmly established as the primary bioanalytical tool for ADME studies related to drug discovery and lead optimization (LO). This review focuses on recent advances in LC/MS/MS based bioanalysis in support of drug discovery and LO. The initial part of the article reviews the principal components of LC/MS/MS bioanalysis: sample preparation, chromatography, ionization and mass analysis. In each section, factors affecting high throughput bioanalysis are addressed. Because of the importance of on-line column switching methods to discovery bioanalysis, the section on sample preparation is divided into off-line and on-line approaches. In addition, the discussion of chromatography is limited to reversed phase liquid chromatography with emphasis given to the trend towards high-flow gradient elution techniques. The latter part of the review focuses on considerations for experimental design. In this section, pooling methods such as cassette dosing are discussed along with more highly integrated strategies linking bioanalysis with protocol generation and sample collection. The article concludes by briefly reviewing factors, which affect bioanalytical precision and accuracy, such as ion suppression, analyte stability and metabolite interference.

Statistical Methods for Assessing Stability of Compounds in Whole Blood for Clinical Bioanalysis

The objective of a blood stability study is to assess the stability of a compound in whole blood after storage in collection vessels at room temperature for two to four hours for samples drawn in the clinic, and for six to eight hours for samples drawn elsewhere and transported to the clinic, in order to develop proper sample handling recommendations for clinical studies. Common practice is to transfer blood from a spiked whole blood pool into collection vessels at 24, 3, and 0 hours prior to analysis. A loss of 15% for a specific proportion of replicates, or for the observed mean, compared to the 0 hour control mean, is often used to decide whether there is any clinically relevant instability at 3 and 24 hours. This procedure is easy to implement, and meets Food and Drug Administration requirements, but it has unknown and uncontrolled risks of incorrect decisions (failing to detect a truly unstable compound, or falsely concluding instability). Investigations were conducted to evaluate various data analysis and decision procedures that control these risks of incorrect decisions, and to optimize the study design and sample size. The recommended data analysis procedure is a linear regression analysis, with an equivalence test for comparing predicted mean concentrations at time = x hours versus the zero hour control, with ±15% specification limits. A study design with n = 9 replicates at 0, 3, 6, and 24 hours yields sufficient power for demonstrating stability.

Reactive oxygen species, cell signaling, and cell injury

Oxidative stress has traditionally been viewed as a stochastic process of cell damage resulting from aerobic metabolism, and antioxidants have been viewed simply as free radical scavengers. Only recently has it been recognized that reactive oxygen species (ROS) are widely used as second messengers to propagate proinflammatory or growth-stimulatory signals. With this knowledge has come the corollary realization that oxidative stress and chronic inflammation are related, perhaps inseparable phenomena. New pharmacological strategies aimed at supplementing antioxidant defense systems while antagonizing redox-sensitive signal transduction may allow improved clinical management of chronic inflammatory or degenerative conditions, including Alzheimer’s disease. Introduction of antioxidant therapies into mainstream medicine is possible and promising, but will require significant advances in basic cell biology, pharmacology, and clinical bioanalysis.