Total Drug Analysis for Pharmacokinetic Studies

MultiScreen® Deep Well and MultiScreen Solvinert Filter Plates

Determining the concentration of drug in plasma or serum at various time points after administration is necessary to calculate the pharmacokinetics (PK) of a drug. PK, in turn, is an important component in the absorption, distribution, metabolism, and excretion (ADME) profile. Precise knowledge of ADME properties enables accurate determination of the proper drug dosage to maintain therapeutic drug levels without risking toxicity.

MultiScreen Deep Well Solvinert and MultiScreen Solvinert filter plates are pre-validated for in-plate precipitation of proteins from plasma or serum for total drug analysis. The plates enable fast, discreet and complete filtrate transfer to provide an automation-compatible platform for sample preparation prior to total drug analysis. Filtration with the Solvinert family of filter plates provides protein-free filtrate that is compatible with HPLC-MS or HPLC-UV analysis.

The MultiScreen Deep Well and MultiScreen Solvinert filter plates are robust and reliable platforms that generate reproducible results. Samples isolated from serum by protein precipitation and filtration through these plates are essentially protein-free and show high compound recovery and no interference from extractables.

Automation-compatible MultiScreen Deep Well Solvinert Filter Plates Yield Reproducible Results for Total Drug Determination

Warfarin was spiked into bovine serum followed by protein precipitation and filtration through MultiScreen Deep Well Solvinert filter plates. The assay was carried out manually and with complete automation. Drug concentrations in the filtrates were analyzed by LC-MS/MS and are compared. The linearity of results for both automated and manual methods (R₂ values= .999) demonstrates that drug samples in serum can be reliably prepared manually or automated by precipitation and filtration in a MultiScreen Deep Well Solvinert filter plate. The high degree of linearity indicates that filtrates generated following this procedure allow accurate LC-MS/MS analysis across a wide concentration range.

High Performance Plate Designs

Automation-compatible MultiScreen Solvinert filter plates are available in 96-well deep well (2 mL) and standard (500 µL) formats. The one-piece plate designs incorporate rigid sidewalls to facilitate use with robotic gripper arms and provide space for barcode labels.

All MultiScreen Solvinert plate materials are selected for broad chemical compatibility and enable extended in-plate incubations with no leaking.

Optimized for Drug Discovery and HPLC Sample Preparation

MultiScreen Solvinert filter plates – both deep well and standard – are optimized for drug discovery applications including total drug analysis, NCE cleavage from solid phase libraries, and sample preparation prior to HPLC or LC/MS/MS. The plates and membranes demonstrate low binding, low extractables and high recoveries. For chromatography separations, the MultiScreen Column Loader accessory can be used to create 96 minicolumns per plate.

MultiScreen Deep Well with hydrophobic membrane and prefilter is also well suited for total drug analysis in plasma by protein precipitation.

Hydrophilic and Hydrophobic PTFE Membranes Available

MultiScreen Solvinert filter plates are available with chemically-resistant hydrophilic and hydrophobic membranes to accommodate aqueous and non-aqueous samples. MultiScreen Deep Well Solvinert filter plates are also available with an optional pre-filter to use with highly particulate media. Both membranes are highly retentive (>99% retention of acid precipitated BSA).

For the broadest chemical resistance, hydrophobic PTFE membrane is recommended. Designed for extended sample incubation times and the lowest extractables, hydrophobic PTFE membrane is ideal for NCE cleavage and cleanup. It is also suitable for in-plate protein precipitation and sample recovery following in-plate compound cleavage from solids or beads. The plates are also used for peptide synthesis.

Hydrophilic PTFE membrane is optimized for low drug and protein binding with excellent throughput in typical aqueous and solvent sample preparation. High sample recoveries and low extractables provide for optimum analysis by HPLC and LC/MS/MS. The membrane is suitable for applications including natural product screening, aqueous solubility testing and total drug analysis.

Performance

High Recovery of Drug in Solvent-based Preparations

Seven drugs were tested for percent recovery by acetonitrile plasma precipitation. Plasma stock samples (5 mL) were spiked with drug (100 µM stock and tritiated) to a final 5 µM drug concentration followed by 1-hour incubation. Protein was precipitated by the addition of acetonitrile (15 mL) and the solution was vortexed vigorously. For each drug a 300 µL aliquot of the supernatant was added to 8 wells per plate. The samples were filtered by vacuum filtration (12" Hg) and filtrates were collected. Percent recovery was determined by comparing an aliquot (100 µL) of filtrate to an aliquot of the precipitated stock (cpm filtrate/cpm precipitated stock). Results show superior drug recovery (>90%) for both hydrophilic and hydrophobic MultiScreen Solvinert plates. (The sample was pre-precipitated by the addition of CACN followed by vigorous mixing.) Equivalent results are seen with MultiScreen Deep Well Solvinert filter plates.

Note: The storage lid does not have the same solvent resistance properties as the filter plate and can be damaged by exposure to some solvent vapors.
*Dioxane, Hexane and Benzene are not recommended for use in Deep Well plates

The data presented in this chart are a compilation of testing by Millipore with certain chemicals and manufacturers' compatibility recommendations. These data are intended to provide expected results when filtration devices are exposed to chemicals for 48 hours at 25 °C (77 °F), unless otherwise noted.

Table 2. MultiScreen Solvinert Filter Plates are designed to support extended incubations. This solvent compatibility table shows results reported for 200 µL of liquid with 24 hours incubation at room temperature.

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