Millipore, Caliper, validate protocols to aid drug discovery

Showcasing the methods for 96-well solubility, PAMPA and permeability assays at the Lab Automation Show in London, the integrated solutions are developed using Millipore's Multiscreen assay systems and Caliper's Sciclone ALH 3000 Liquid Handling Workstation.

Millipore's MultiScreen Solubility Assay System, MultiScreen Permeability filter plate, and MultiScreen filter plate for PAMPA are part of a family of ADME (absorption, distribution, metabolism and excretion) assays. They are primarily developed for screening drug compounds in the early stages of discovery.

The collaboration between the two companies sees Millipore offering the reagents and consumables while Caliper is to offer the pre-validated automated solution for processing the Millipore reagents and consumables for solubility and permeability analysis.

Suitable for high-throughput solubility or permeability analysis for compound characterization, the assays are an attempt to fill a gap in the market where determining aqueous compound solubility in the early stages of the drug discovery process is becoming increasingly crucial.

Solubility of a compound is important in the Biopharmaceutics Classification System (BCS). BCS classifies compounds based on their solubility and permeability. Low solubility can lead to unreliable results during in-vitro testing. Insoluble precipitates have been shown to cause false positives in bioassays, wasting valuable time and resources.

These issues add significant cost to drug research projects. In addition to these factors, the standard shake-flask method used to evaluate drug solubility is inherently low throughput, labor intensive and not amenable to automation.

Joe Fredette, Caliper's product manager for automated liquid handling products told DrugResearcher.com​: "Early compound characterization is increasingly looked at as a pre-screening approach to cleaning up compound libraries by weeding out those compounds that lack critical properties to be a drug-like compound."​

The permeability assay is a non-cell based assay designed to predict passive, transcellular permeability of drugs in early drug discovery. The assay can also measure the ability of compounds to diffuse from a donor to an acceptor compartment separated by a hexadecane liquid layer on a polycarbonate membrane support.

The Parallel Artificial Membrane Permeability Assay (PAMPA) uses a lipid filled membrane to simulate the lipid bilayer of various cell types, including intestinal epithelium. These non-cell based permeability assays are automation compatible, relatively fast (4-24 hours), inexpensive, and straightforward.

They are being used with increasing frequency to determine the passive, transcellular permeability properties of potential drug compounds. The permeability assays that measure passive transport through lipophilic barriers correlate with human drug absorption values from published methods.

The 96-well solubility assay is an automated method for determining drug solubility. The assay provides a means to estimate the aqueous solubility of hundreds of compounds per day improved drug recovery for reliable determination of soluble compound concentration. It has the benefit of insoluble particle retention reducing the chance of false positive readings.

Fredette added: "These three distinct methods were tested, optimised, and validated in about 6 months with the aim of focussing this product to the biopharmaceutical and life science discovery markets."​