Poster: A 3D Printed Fluidic Device, Amenable to Automated Instrumentation, for Optimization of Pharmacokinetic Studies
Poster presentation at SLAS2014.
Sarah Y. Lockwood, B.S. in Chemisty
Graduate Student, Michigan State University
In vitro pharmacokinetic (PK) models offer an appealing, viable option to increase efficiency of the drug development process when working in tandem with animal models. Enhancing efficiency has received increasing attention in recent years due to the climbing cost of bring a drug to market, which is rapidly reaching one billion dollars.
Static, in vitro models used in the drug discovery industry are ideal for monitoring pharmacodynamic profiling, but the inability to manipulate drug concentrations challenges the ability to generate PK information. Dynamic, in vitro models (DIVM) offer more flexibility with regards to varying drug concentrations, but the integrity of the sample (cells or bacteria) can be compromised due to dilution methods. The sample is conserved in a diffusion-based DIVM by separating direct flow from the sample through the use of a membrane filter, which allows for fresh nutrients, drugs, and oxygen to diffuse to the sample, while simultaneously removing created waste. Industry-established diffusion-based DIVM, such as the hollow fiber chamber reactor (HFCR), successfully mimic PK profiles obtained using animal models. Unfortunately, the HFCR consumes large volumes of drug, thus placing strain on synthetic chemists. Furthermore, the HFCR setup makes it difficult to recover samples (e.g., the drug-affected cells) for post-exposure analysis, nor are these measurements amenable to automation.
Traditional microfluidic technologies can alleviate some challenges associated with the HFCR, i.e., volume and sample recovery, but the lack of automation potential, present in current pharmaceutical infrastructures, would hinder such devices being used in industry. Fluidic devices created by 3D printing offer a rigid, reusable platform applicable for automated infrastructure present in industry that is based on microwell plates. Clearance and loading profiles of fluorescein and linezolid (an antibiotic), obtained using either a fluorescence plate reader or mass spectrometer, mimic those observed in conventional PK profiles. Using the diffusion based DIVM, a well, (cell culture insert) containing sample was administered a single micromolar dose of linezolid or fluorescein by diffusion across a membrane. This membrane allows for the separation of the well from a channel containing initial concentrations of linezolid (5 ?M) and fluorescein (10 ?M) which were flowed at 10 ?L/min. Every 30 min, 5 ?L was sampled from each well, further diluted and analyzed. Half lives of less than 45 minutes for both compounds were achieved and could be manipulated depending upon flow rate, pore size, and initial loading dose. Importantly, due to the features of the printed device, specifically the cell culture insert, this device can be re-used or operated for hours without leaking, enabling for dosing regimens. Other key advantages of 3D-printed devices are the absence of laboratory steps during creation of the device and electronic file sharing of the device design with other laboratories.