Abstract
Introduction: The use of sunscreens is recommended to reduce skin damage and prevent skin cancer. However, evidence has shown that sunscreen can undergo degradation processes induced by ultraviolet (UV) radiation which can lead to reduction or loss of photoprotective capacity, generation of free radicals and toxic intermediates which react with skin structures generating biological damage. Objective: To evaluate the photostability of four sunscreen formulations with Sun Protection Factor (SPF) 30 added by different chemical and physical UV filters. Material and Methods: Each product was exposed to solar radiation from 10 a.m. to 15 p.m. (UV index: 6.0). The areas under the curves (AUC) of the absorbance spectrum of the formulations before and after radiation exposure were used to calculate the ratio between the AUC before and after the solar radiation (AUCI). Results: Only two formulations, which presented the AUCI higher than 0.8, were considered photostable. Despite having the same SPF 30, formulations showed different absorption spectrum in regions of UVA1, UVA2 and UVB and the photostability of the products tested varied considerably. Conclusion: The development of photostable formulations is critical because degradation products of UV filters can act as photo-oxidants. Furthermore, increased exposure to UV radiation due to the reduction of the photoprotective capacity of unstable products increases the risk of burns and skin cancer.
Highlights
The use of sunscreens is recommended to reduce skin damage and prevent skin cancer
Skin cancer is the main damage resulting from this exposure but this risk factor can be reduced with preventive actions and especially, the use of broad spectrum sunscreens with reapplication.[1,6,7,8]
The inorganic UV filters are called physical, since their mode of protection against solar radiation is associated with physical phenomena, such as scattering and reflection of ultraviolet radiation (UVR).[16,17]
Summary
The use of sunscreens is recommended to reduce skin damage and prevent skin cancer. evidence has shown that sunscreen can undergo degradation processes induced by ultraviolet (UV) radiation which can lead to reduction or loss of photoprotective capacity, generation of free radicals and toxic intermediates which react with skin structures generating biological damage. Skin cancer is the main damage resulting from this exposure but this risk factor can be reduced with preventive actions (sun exposure in periods of lower incidence, use of appropriate clothing and accessories) and especially, the use of broad spectrum sunscreens with reapplication.[1,6,7,8] In this sense, the use of UV-filters incorporated in sunscreen formulations is the most indicated method for preventing skin injury induced by sun over-exposure.[1,9,10,11,12,13]. Sunscreens are photochemical systems containing UV active substances capable of absorbing, reflecting and/or dispersing the radiation that penetrates the skin These substances can be divided into organic and inorganic filters.[14,15] Typically, the organic filters are called chemical filters, as their mode of action is related to chemical changes in their molecules that prevent UV radiation reaching the skin. The inorganic UV filters are called physical, since their mode of protection against solar radiation is associated with physical phenomena, such as scattering and reflection of UVR.[16,17]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call