Rapid pharmacokinetic screening for the selection of new drug discovery candidates using a generic isocratic liquid chromatography--atmospheric pressure ionization tandem mass spectrometry method

One-step method for plasma determination of ibuprofen by chemiluminescence-coupled ultrafiltration and application in a pharmacokinetic study

A simple one-step method is established for plasma determination of ibuprofen and its pharmacokinetic study. The method involves simple sample pre-treatment by dilution, rapid separation by ultrafiltration (UF) and online sensitive detection by chemiluminescence (CL) based on significant intensity enhancement of ibuprofen on the weak CL of potassium permanganate and sodium sulphite in an acidic system. The calibration curve for ibuprofen is linear in the range 0.1-50.0 µg/mL in rat plasma. Average recoveries of ibuprofen at 0.80, 12.0 and 40.0 µg/mL amounted to 98.0 ± 4.2%, 101.2 ± 3.6% and 99.3 ± 5.4%, respectively. Standard deviations of intra- and inter-day measurement precision and accuracy are within ±10.0%. The detection limit for ibuprofen is 10.0 µg/L in plasma samples. Pharmacokinetic study of ibuprofen by the validated method shows that the mean plasma drug concentration-time course confirms to a classical two-compartment open model with first-order absorption. The proposed method will be an alternative for pre-clinical pharmacokinetic study of ibuprofen and other non-steroidal anti-inflammatory drugs.

Mass spectrometry for the quantification of bioactive peptides in biological fluids

The study of pharmacologically active peptides is central to the understanding of disease and development of novel therapies. It would be advantageous to monitor the fate of bioactive peptides in biological fluids and tissues following their in vivo administration (exogenous administration) or the modulation of endogenous factors (e.g., peptide hormones) affected by the administration of a pharmacological agent. Measurement of administered compounds (small molecules) in plasma is a mature field. However, measurement of pharmacologically active peptides presents particular problems for quantitative mass spectrometry, including challenges from selectivity and sensitivity perspectives. Current approaches towards peptide quantification in biological fluids include immunoassays and mass spectrometric techniques. Immunoassays, although sensitive, lack the necessary selectivity for distinction between peptide and metabolites. Modified molecules induced by metabolic transformations (e.g., N- or C-terminal truncation of the peptide) might not be differentiated by the antibody used in the assay, leading to cross-reactivity. However, although it is generally accepted that mass spectrometry is an ideal technique for the quantification of trace levels of analytes in biological fluids, immunological techniques are still characterized by better limits of peptide detection. In this review article, novel mass spectrometric approaches and strategies on peptide quantification will be described. The current capabilities and prospects for advances in this critical area of research will be examined.

Development of a semi-automated chemical stability system to analyze solution based formulations in support of discovery candidate selection

A semi-automated chemical stability system was developed, validated, and implemented to assess the chemical and physical stability (24 h) of intravenous and oral solution based formulations in support of preliminary in vivo drug discovery studies. The system utilizes a single Agilent 1100 LC and Xterra column with multiple UV wavelength monitoring. Mobile phase selection, either basic or acidic, is selected base upon on the physico-chemical properties of the test compound. The system was validated against 14 new chemical entities across multiple therapeutic areas. The results indicated that drug discovery compounds could be accurately quantified (<2% R.S.D.) in a wide range of formulation vehicles in greater than 90% of the test cases. This method can be used as a quantitative tool for triaging formulation variables and packaging configurations to quickly develop stable solutions for dosing.

Evaluation of the use of LC-MS in supporting stability studies for preclinical study formulations

Assessing the short-term stability of drug development candidates in one or more formulations to be used during their preclinical evaluation is a routine, but important, task. Typically, this is based on data generated by HPLC with ultraviolet detection of the species of interest and using methodology specifically developed and validated for the purpose. This work describes a feasibility study conducted into the use of HPLC with mass spectroscopic detection for work of this type. Experimental details and the results of trials with three different drugs, each in a different vehicle, are given. It was concluded that, by using mass spectroscopic detection, a well-defined strategy could be used to generate stability data, which offered advantages in terms of specificity, speed and sensitivity over that typically used.

Progress in liquid chromatography-mass spectrometry instrumentation and its impact on high-throughput screening

In the past 10 years, liquid chromatography-mass spectrometry (LC-MS) has rapidly matured to become a very powerful and useful analytical tool that is widely applied in many areas of chemistry, pharmaceutical sciences and biochemistry. In this paper, recent instrumental developments in LC-MS-related interfacing, ionization and mass analysis are reviewed from the perspective of the application of LC-MS in high-throughput screening of combinatorial libraries and the related high-throughput quantitative bioanalysis in early drug-discovery studies, such as early adsorption, distribution, metabolism and excretion studies.