Raman spectroscopy as a tool to accelerate development of complex medicinal products

Regulatory approval of complex generic drug products that are applied topically to treat skin disease can be challenging because a standard method to assess cutaneous pharmacokinetics in vivo is not available. As a result, expensive and prolonged clinical trials are often necessary, and this has proved to be a significant disincentive to generic product development and restrictive of patient access to more affordable medicines. Here, the proof-of-concept of a regulatory science tool using Raman spectroscopy is demonstrated to enable an objective and more efficient assessment of complex (topical) generic drug products and to show bioequivalence with a reference-listed formulation. Raman spectroscopy is demonstrated to be able to quantify the relative spatiotemporal disposition of metronidazole (a drug used to treat rosacea) within the skin and proximal to its site of pharmacological action. Analysis of the data permits pharmacokinetic metrics to be extracted and compared between different gel and solution formulations with the potential to establish bioequivalence and enable more efficient complex generic drug product development.