Validating Otto: a Franz diffusion cell autosampler to automate in vitro permeation studies

Area of Science:

• Pharmacokinetics and Drug Delivery
• Analytical Chemistry
• Biomedical Engineering

Background:

• The Franz diffusion cell (FDC) is a standard apparatus for in vitro drug permeation studies.
• Traditional FDC methods require manual sampling and refilling, leading to scheduling challenges, time inefficiency, and labor intensity.
• Automation is needed to enhance the reliability and throughput of FDC-based permeation assays.

Purpose of the Study:

• To develop and validate an automated sampling and refilling system, named Otto, for retrofitting generic Franz diffusion cells.
• To assess the performance of the Otto autosampler in terms of volume consistency, accuracy, and unattended operation.
• To evaluate the impact of automated sampling on the quality of in vitro drug permeation data.

Main Methods:

• Development of the Otto autosampler, designed for automated sampling and refilling of FDCs.
• Validation using Methylene Blue (MB) as a model drug to determine sample volume consistency and accuracy.
• Comparison of Otto's performance against manual sampling in terms of sample volume variability and drug recovery.
• Application of Otto in a 24-hour in vitro ibuprofen permeation study, collecting up to 100 samples unattended.

Main Results:

• Otto demonstrated superior sample volume consistency (CV = 3.2%) compared to manual operation (CV = 7.4%).
• The measured amount of Methylene Blue across multiple cycles accurately reflected theoretical and manually determined amounts.
• The autosampler successfully collected numerous samples unattended over 24 hours, integrating with standard analytical workflows.
• Automated, continuous sampling by Otto effectively maintained sink conditions during ibuprofen permeation studies.

Conclusions:

• The Otto autosampler provides a cost-effective, reliable, and high-performance solution for automating Franz diffusion cell permeation studies.
• Automated sampling significantly improves the consistency and quality of in vitro drug permeation data.
• Otto enables unattended, long-term monitoring, enhancing experimental efficiency and data integrity in drug delivery research.