FDA’s Clinical Trials to Study the Absorption of Sunscreen Active Ingredients | FDA

Shedding More Light on Sunscreen Absorption | FDA

FDA’s Clinical Trials to Study the Absorption of Sunscreen Active Ingredients

Over-the-counter sunscreens are routinely used for the prevention of skin damage and cancer, however little has been known about the systemic absorption of most active ingredients. A human absorption study, also referred to as a maximal usage trial (MUsT), is used to determine the concentration of a topical drug product in plasma after applying it to the skin according to the product labeling. Because MUsTs had not been performed previously for sunscreens, FDA’s Division of Applied Regulatory Science in the Office of Clinical Pharmacology conducted two clinical trials to demonstrate the feasibility of these studies and collect preliminary data that covered seven commercially-available formulations with different combinations of seven sunscreen active ingredients (1, 2). Both studies, published in JAMA, demonstrated that all the studied sunscreen active ingredients were absorbed in appreciable quantities when applied to 75% of body surface area, which is the area outside of normal swimwear. The second study demonstrated that absorption occurred after a single application and that active ingredients can remain in plasma for an extended time after the last application. While these studies demonstrated that sunscreen active ingredients are absorbed, that does not mean they are unsafe. The findings reinforce the need for further testing to determine the safety of those ingredients for repeated use over a lifetime. In a recent podcast and print interview in JAMA (3, 4), Dr. David Strauss, head of FDA’s Division of Applied Regulatory Science, reemphasized that given the recognized public health benefits of sunscreen, FDA strongly advises the continued use of broad-spectrum sunscreen of SPF 15 or higher in conjunction with other sun-protective measures. Additional considerations are discussed in a recent FDA commentary on sunscreen safety that accompanies the American Society of Oncology’s new policy statement on skin cancer prevention. Dr. Strauss and Dr. Theresa Michele, head of FDA’s Office of Nonprescription Drugs, highlight the importance of clinicians in advising patients on proper use of sunscreen and other sun-protective behaviors (5). Additional Information Further information on FDA’s sunscreen studies can be found at https://www.fda.gov/news-events/fda-voices/shedding-more-light-sunscreen-absorption. For information about MUsT and assessment of systemic exposure of over-the-counter monograph topical drug products, click here: https://www.fda.gov/media/140321/download. For more information on how FDA’s Division of Applied Regulatory Science tackles drug development, public health and regulatory questions such as this one, see: https://www.fda.gov/about-fda/center-drug-evaluation-and-research-cder/division-applied-regulatory-science. References Matta MK, Zusterzeel R, Pilli NR, et al. Effect of Sunscreen Application Under Maximal Use Conditions on Plasma Concentration of Sunscreen Active Ingredients: A Randomized Clinical Trial. JAMA. 2019 Jun 4;321(21):2082-2091. https://doi.org/10.1001/jama.2019.5586. Matta MK, Florian J, Zusterzeel R, et al. Effect of Sunscreen Application on Plasma Concentration of Sunscreen Active Ingredients: A Randomized Clinical Trial. JAMA. 2020 Jan 21;323(3):256-267. https://doi.org/10.1001/jama.2019.20747. Podcast: Risk Uncertain From Sunscreen Ingredients in Blood. https://edhub.ama-assn.org/jn-learning/audio-player/18393763 Abbasi J. FDA Trials Find Sunscreen Ingredients in Blood, but Risk Is Uncertain. JAMA. 2020;323(15):1431-1432. https://doi.org/10.1001/jama.2020.0792. Strauss D and Michele TM. Skin Cancer Prevention and Sunscreen Safety: Commentary on American Society of Clinical Oncology Policy Statement on Skin Cancer Prevention. JCO Oncology Practice. https://ascopubs.org/doi/10.1200/OP.20.00425

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