A review of bioanalytical methods for the therapeutic drug monitoring of ß-lactam antibiotics in critically ill patients: Evaluation of the approaches used to develop and validate quality attributes.

Due to their broad spectrum of activity and wide therapeutic index, ß-lactam antibiotics (ß-LA) are commonly used to treat severe sepsis in critically ill patients in intensive care units. This group of patients experiences important physiological changes that alter their pharmacokinetics, and thus, therapeutic drug monitoring (TDM) of ß-LA is increasingly used to improve personalized medicine by optimizing doses and minimizing the emergence of drug-resistant bacterial strains. Reliable and high-quality bioanalytical methods are needed in clinical practice. This review principally focuses on evaluating the development and validation of state-of-the-art analytical methods for the determination of ß-LA in biological samples from critically ill patients. When mentioned, method optimization was performed using a univariate strategy, the currently used analytical quality by design (AQbD) tools were not used for method optimization in any study. Liquid chromatography methods coupled with UV or MS detectors were the main techniques used, and the pretreatment procedures were still considerably complex for a hospital laboratory setting. Given the poly-medication status of many patients, the selectivity of the procedure must be specifically analyzed to avoid possible interference from other drugs. However, this aspect has been assessed in very few studies. We also identified inconsistencies in analytical ranges selected in many published methods, since they are not centered in the therapeutic concentrations of the antibiotics. The precision, accuracy and linearity were mainly evaluated using diverse bioanalytical validation guidelines; however, more detailed information could have been provided about the calibration strategy used for routine laboratory assessments.

Acyl migration incidence on accuracy of a triacylglycerol regioanalysis--a theoretical evaluation.

We will consider the Grignard chemical deacylation to study the regioanalysis of triacylglycerols (TAGs). Using a given TAG structure, a cross-contamination model is developed and used for evaluating the incidence of the acyl migration and its influence on the accuracy of a regiospecific analysis of the molecule. Despite unavoidable isomerization, the newly formed alpha,beta-diacylglycerols are considered as most representative of the original TAG composition. In this paper, we present evidence that in conditions of limited acyl migration, the regiospecific distribution could more accurately be determined from the alpha-monoacylglycerol rather than through calculations based on the alpha,beta-diacylglycerols fraction.

A direct method for regiospecific analysis of TAG using alpha-MAG.

An analytical procedure was developed for regiodistribution analysis of TAG using alpha-MAG prepared by an ethyl magnesium bromide deacylation. In the present communication, the deacylation procedure is shown to lead to representative alpha-MAG, allowing the composition of the native TAG in the alpha-position to be determined directly. The composition in the beta-position can then be estimated from the composition of the alpha-MAG and TAG according to the formula 3 x TAG - 2 x alpha-MAG. The estimates are superior to those obtained using the alpha,beta-DAG and Brockerhoff calculations as they come closer to the theoretical value and have smaller SD. The present procedure, first demonstrated on a synthetic TAG, was then successfully applied to the analysis of borage oil, milkfat, and tuna oil.