A high throughput solubility assay for drug discovery using microscale shake-flask and rapid UHPLC-UV-CLND quantification.

The rapid determination of key physical properties of lead compounds is essential to the drug discovery process. Solubility is one of the most important properties since good solubility is needed not only for obtaining reliable in vitro and in vivo assay results in early discovery but also to ensure sufficient concentration of the drug being in circulation to get the desired therapeutic exposure at the target of interest. In order for medicinal chemists to tune solubility of lead compounds, a rapid assay is needed to provide solubility data that is accurate and predictive so that it can be reliably used for designing the next generation of compounds with improved properties. To ensure speed and data quality, we developed a high throughput solubility assay that utilizes a single calibration UHPLC-UV-CLND method and a 24h shake-flask format for rapid quantification. A set of 46 model compounds was used to demonstrate that the method is accurate, reproducible and predictive. Here we present development of the assay, including evaluation of quantification method, filtration membranes, equilibrium times, DMSO concentrations, and buffer conditions. A comparison of thermodynamic solubility results to our high throughput 24h shake-flask solubility assay results is also discussed.

A charged aerosol detector/chemiluminescent nitrogen detector/liquid chromatography/mass spectrometry system for regular and fragment compound analysis in drug discovery.

In this paper, we introduce a high throughput LCMS/UV/CAD/CLND system that improves upon previously reported systems by increasing both the quantitation accuracy and the range of compounds amenable to testing, in particular, low molecular weight "fragment" compounds. This system consists of a charged aerosol detector (CAD) and chemiluminescent nitrogen detector (CLND) added to a LCMS/UV system. Our results show that the addition of CAD and CLND to LCMS/UV is more reliable for concentration determination for a wider range of compounds than either detector alone. Our setup also allows for the parallel analysis of each sample by all four detectors and so does not significantly increase run time per sample.

A novel method for high throughput lipophilicity determination by microscale shake flask and liquid chromatography tandem mass spectrometry.

Modern small molecule drug design requires the optimization of not only the binding characteristics of the molecule but also its physicochemical properties for ADMET performance. A key physical property is lipophilicity and medicinal chemists need rapid access to high quality data in order to drive their decision making. Traditionally lipophilicity (log D) measurements are performed with a shake flask method and UV determination. This method suffers from low sensitivity and is not easily converted to a high throughput format. Over the past decade, several groups have taken different approaches to improve this assay, including replacing the shake flask method with one that utilizes reverse phase HPLC. Here we describe a new microscale shake flask method that utilizes UPLC-MS/MS to achieve increased throughput, sensitivity and accuracy. Approaches for assessing data quality are also described. This platform technology only requires micrograms of compound and is routinely used by most small molecule drug discovery project teams at Genentech.