New ReactArray™ ST for Fully Automated Equilibrium Solubility Testing

Exhaustive drug solubility screening early in the development process has become an important focus for pharmaceutical scientists.

Low solubility can hamper a drug's bioavailability and make ADME assays more difficult. Solubility assays are also vital for development scientists who need to select amongst salt or crystalline forms, evaluate formulation excipients and determine minimum absorbable dose. The unique new ReactArray™ ST Automated Equilibrium Solubility Testing Workstation now enables faster, more convenient and efficient gathering of this critical data under completely controlled conditions.

ReactArray ST, based on the proven ReactArray 215SW platform is fitted with a ten position Reactivate rack with individual temperature (-30^oC to 150^oC) and stirring control. A new design study vessel (patent applied for) includes a spring loaded filter. During sampling, the workstation probe presses the test device down into the slurry at equilibrium; the probe is then able to take a quantitative filtered sample for subsequent HPLC analysis. The test device has been shown to deliver excellent data across a wide range of solvents and temperatures.

The system brings many advantages over traditional manual studies where temperature controlled centrifuges are used to spin down slurries at equilibrium prior to sampling with a heated needle. Alternatively, manual samples can be taken through a filter device. These approaches deliver poor reproducibility and suffer from material crashing out of solution and being lost within the sampling device. ReactArray ST allows samples to be taken automatically, with complete safety, even at elevated temperatures. These samples can then be automatically diluted and transferred to the HPLC system for analysis.

ReactArray ST is calibrated so that concentrations can be plotted as a bar graph (single temperature studies), or as a solubility curve (multiple temperature studies). ReactArray ST provides equilibrium solubility values that are widely recognized as the true solubility data and of greatest use in establishing in-process parameters and bioavailability.

ReactArray ST software is even able to deal with the wide analyte concentration range which would normally create HPLC quantitation errors.

In tests performed at leading pharmaceutical companies, equilibrium solubility data obtained by ReactArray ST showed good agreement with published data... ReactArray ST also increases the probability of development success by increasing the breadth of solvent, solvent mixtures and various pH buffers that can be practically studied.

ReactArray workstations have been developed through collaboration between Anachem and chemists within the pharmaceutical industry to provide a proven and robust concept that meets the demand for high throughput reaction screening and optimization. Today there are over 200 systems in use worldwide. Anachem is a leading supplier of laboratory equipment and services, established for over thirty five years with key expertise in liquid handling, chromatography, automation and process optimization solutions.