In Vitro Testing of Sunscreens for Dermal Absorption: A Platform for Product Selection for Maximal Usage Clinical...

Area of Science:

• Dermatology
• Cosmetic Science
• Pharmacokinetics

Background:

• Sunscreen products utilize UV filters for skin protection against ultraviolet radiation (UVR).
• The US FDA requires additional safety data, including dermal absorption, for UV filters.
• In vitro skin permeation tests (IVPTs) are recommended by the FDA to predict in vivo absorption and guide clinical trial formulation selection.

Purpose of the Study:

• To report in vitro methodologies for selecting sunscreen products for an FDA-sponsored clinical trial.
• To determine the skin absorption potential of common UV filters in commercially available sunscreen products using IVPT.
• To identify formulation properties that may indicate UV filter dermal absorption.

Main Methods:

• Development of an in vitro skin permeation test (IVPT) method utilizing human cadaver skin.
• Testing of commercially available sunscreen products to evaluate UV filter skin absorption.
• Characterization of sunscreen formulation properties, including globule size in emulsions.

Main Results:

• All tested sunscreen products exhibited some degree of UV filter dermal absorption via IVPT.
• A rank order of sunscreen product absorption potential was established.
• Globule size in sunscreen emulsions was identified as a potential indicator for the absorption rank order.

Conclusions:

• In vitro skin permeation tests (IVPTs) are valuable for assessing UV filter absorption and selecting sunscreen formulations for clinical studies.
• Sunscreen formulation properties, such as globule size, can influence UV filter dermal absorption.
• This methodology aids in understanding systemic exposure of UV filters and supports FDA safety data requirements.