The surrogate scaffold method for quantifying molecular release kinetics from drug delivery systems

The accurate determination of kinetics of therapeutic release from drug delivery vehicles is an essential step in the optimized design of such systems for biomedical and pharmaceutical applications. Most methods in current use for quantifying therapeutic release rates are developed to provide consistency, reproducibility, and ease of usage in a laboratory setting. These methods, however, do not necessarily mirror the release conditions when the drug delivery system comes into contact with the target tissue environment during application. As a result, the findings from these studies provide only comparative guidelines about the drug delivery rates and duration. Successful optimization of a drug delivery system requires complete, and accurate, knowledge about the release profile over an extended period of time to determine the initial release rate—including burst release if present, the rate of change of the release kinetics, and the maximum duration of delivery at a minimum therapeutic concentration level. We have developed an indirect method for the quantification of release kinetics suitable for nanoparticle-based drug delivery systems that utilizes a hydrogel scaffold as a tissue surrogate to better emulate therapeutic delivery into a target tissue environment. Details of the method and its application to the release of an angiogenic peptide from a nanoparticle emulsion are provided in this communication.