In the development of Azelaic Advanced, optimizing concentration for efficacy and safety was critical. Cell viability assays determined that a 10% concentration of our industry-first solubilized Azelaic acid provided optimal results, as higher concentrations (12% and 14%) demonstrated cytotoxicity. While higher concentrations, such as 15%, are often preferred by consumers due to older and more established prescription products, the cytotoxic results necessitated launching Azelaic Advanced at 10%. Anticipating comparisons to the popular 15% Finacea gel, we initiated penetration studies to demonstrate the bioavailability of our formulation. This article provides detailed insights into the preliminary penetration study and outlines future plans for advanced assessments using a Franz Diffusion test.
Background
The Franz Diffusion test is a widely accepted method for evaluating skin penetration. It involves the use of an apparatus that holds ex-vivo skin samples or skin equivalents over a receptor fluid, which collects substances that penetrate the skin. For Azelaic Advanced, we plan to conduct an advanced Franz Diffusion test using the Relego machine, a cutting-edge device capable of maintaining ex-vivo skin viability for up to 54 days. This collaboration with Relego and a Toronto academic institution will allow for more comprehensive data to be published in a peer-reviewed journal.
However, for this initial study, we utilized the Differential Stripping method developed by Teichmann et al. (2005) to assess penetration into both the stratum corneum and the nucleated layers of live skin. This method was enhanced by incorporating recent extraction techniques from Kadam et al. (2023), ensuring accuracy and reproducibility in quantifying Azelaic acid penetration.
Methods
Test Subjects and Preparation
The study involved six participants who refrained from applying any topical products to their forearms for three days prior to testing. Four 1-inch circular sites were marked on each forearm, and 10 mg of either Azelaic Advanced (10%) or Finacea (15%) gel was applied to each site, resulting in two application sites per product on each forearm. Participants were instructed to avoid washing or applying anything to the test area for 24 hours.
Tape Stripping Procedure
After 24 hours, tape stripping was performed using D-squames, a pressure tool, and forceps. The first five layers were discarded to eliminate surface contamination. Layers 6–35 were designated as the stratum corneum and pooled into a single beaker, while layers 36–60 were classified as nucleated layers and pooled separately.
Extraction and Analysis
The tape strips were soaked in ethanol, and Azelaic acid was extracted using an ultrasonic device. Three aliquots were taken from each pooled sample and analyzed using UV-Vis spectrophotometry at 204 nm. Ethanol with unused D-squames served as the blank.
Results
The data revealed a significant improvement in penetration with Azelaic Advanced compared to Finacea 15% Gel.
The pooled layers 6-35 correspond to the Stratum Corneum layers. The results show that 49.2% ± 4.5% of the applied Azelaic acid penetrated the Stratum Corneum layers for Azelaic Advanced, while
The pooled layers 36-60 represent the nucleated layers of the epidermis corresponding to the Stratum Granulosum and potentially some of the Stratum Lucidum. The results show that 16.2%
The total percentage of Azelaic acid that were detected in the stripped layers was 65.4% for Azelaic Advanced and 13.7% for Finacea 15% Gel.
Discussion
The superior penetration of Azelaic Advanced can be attributed to its innovative formulation. Unlike Finacea, which is a suspension containing micronized crystals (~1 μm), Azelaic Advanced contains fully solubilized Azelaic Acid. In addition, the formulation features a crystal clear microemulsion, with droplet sizes of 50-100 nm, facilitating enhanced skin penetration by improving the bioavailability of Azelaic acid and promoting deeper layer absorption.
Future Directions
The initial findings validate the enhanced penetration capabilities of Azelaic Advanced. To substantiate these results further, we are collaborating with Relego and an academic institution for a Franz Diffusion test using viable ex-vivo skin. This study will provide more comprehensive insights into the pharmacokinetics of Azelaic Advanced, supporting its clinical and consumer benefits. Furthermore, the future study will address some limitations in this current study such as 1) The amount that stayed on top of the skin cannot be measured in this study 2) The amount that penetrated past the epidermis cannot be measured 3) Environmental effects impacting skin penetration.
Conclusion
The Differential Stripping study demonstrates that Azelaic Advanced delivers significantly higher levels of Azelaic acid into the skin compared to Finacea, despite its lower concentration. This highlights the importance of formulation science in skincare product development and underscores the potential of Azelaic Advanced as a game-changing treatment in dermatological care.
References
Kadam, T. V., & Darekar, A. B. (2023). Spectrophotometric Method for Determination of Azelaic Acid: Development and Validation Approach. Advanced Concepts in Pharmaceutical Research Vol. 3, 207–214. https://doi.org/10.9734/bpi/acpr/v3/6663C
Teichmann, A., Jacobi, U., Ossadnik, M., Richter, H., Koch, S., Sterry, W., & Lademann, J. (2005). Differential stripping: determination of the amount of topically applied substances penetrated into the hair follicles. The Journal of investigative dermatology, 125(2), 264–269. https://doi.org/10.1111/j.0022-202X.2005.23779.x