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Avobenzone

Also known as: Avobenzone, Parsol 1789, Butyl Methoxydibenzoylmethane, 1-(4-Methoxyphenyl)-3-(4-tert-butylphenyl)propane-1,3-dione

Overview

Avobenzone is a synthetic, oil-soluble chemical compound widely used in sunscreen products as a UVA filter. It protects the skin by absorbing UVA radiation, which is responsible for premature aging and increases the risk of skin cancer. Avobenzone exists in both enol and keto forms, with the enol form being more stable in solution. A key challenge with avobenzone is its photoinstability; upon exposure to sunlight, it degrades and loses its effectiveness. To mitigate this, it is often combined with other UV filters like octocrylene or formulated with photostabilizers. Avobenzone is not naturally derived and is exclusively produced synthetically. It is available in various sunscreen formulations, including creams, lotions, and sprays. Research on avobenzone is extensive, focusing on improving its stability and assessing its systemic absorption.

Benefits

Avobenzone's primary benefit is its ability to protect the skin from UVA radiation, thereby reducing the risk of photoaging and skin cancer. It is effective in preventing sunburn and long-term skin damage caused by UVA rays. Avobenzone is often combined with other UV filters to provide broad-spectrum protection against both UVA and UVB radiation. Studies have shown that consistent use of sunscreens containing avobenzone can significantly reduce the incidence of melanoma and other skin cancers, particularly in fair-skinned individuals. The effectiveness of avobenzone depends on its concentration in the sunscreen formulation and the frequency of application. While beneficial, its photoinstability requires it to be paired with stabilizing agents for optimal performance.

How it works

Avobenzone functions as a chemical UV filter by absorbing high-energy UVA radiation and converting it into lower-energy radiation (heat), which is then released from the skin. This process prevents the harmful UVA rays from penetrating deeper into the skin layers and causing damage to cells and DNA. Avobenzone does not target specific molecular pathways but acts as a physical barrier against UV radiation. While primarily interacting with the skin, studies have shown that avobenzone can be absorbed systemically, although the extent and implications of this absorption are still under investigation. Its effectiveness relies on its ability to maintain stability upon exposure to sunlight, which is often achieved through combination with other stabilizing compounds.

Side effects

Avobenzone is generally considered safe for topical use in sunscreens, but some potential side effects and safety considerations exist. Skin irritation or allergic contact dermatitis are rare but possible, particularly in individuals with sensitive skin. Systemic absorption of avobenzone has been documented in several studies, raising concerns about potential endocrine disruption, although the clinical significance of this absorption remains unclear. No significant drug interactions have been reported with topical avobenzone use. It is contraindicated in individuals with known hypersensitivity to avobenzone or any of its related compounds. Pregnant and breastfeeding women should consult with a healthcare provider before using products containing avobenzone due to the potential for systemic absorption. While avobenzone is considered safe when used as directed, excessive or prolonged use should be avoided.

Dosage

Avobenzone is typically used in concentrations ranging from 2% to 5% in sunscreen formulations. The optimal dosage depends on the desired Sun Protection Factor (SPF) and the specific formulation of the sunscreen. It should be applied liberally to all exposed skin 15-30 minutes before sun exposure. Reapplication is recommended every two hours, or immediately after swimming or sweating. There is no established maximum safe dose for topical use, but it is advisable to avoid excessive application. The absorption of avobenzone can be affected by the formulation of the sunscreen, with some formulations enhancing absorption more than others. No specific cofactors are required for its effectiveness.

FAQs

How often should I reapply sunscreen with avobenzone?

Reapply sunscreen containing avobenzone every two hours, or immediately after swimming or sweating, to maintain optimal protection. Consistent reapplication is crucial due to avobenzone's potential for degradation upon sun exposure.

Is avobenzone safe for pregnant women?

Pregnant women should consult with a healthcare provider before using products containing avobenzone due to potential systemic absorption. While generally considered safe, it's best to seek medical advice.

Can avobenzone cause skin irritation?

Skin irritation or allergic contact dermatitis is rare but possible, particularly in individuals with sensitive skin. Discontinue use if irritation occurs and consult a dermatologist.

Why is avobenzone often combined with other ingredients in sunscreen?

Avobenzone is often combined with other UV filters and stabilizers to enhance its photostability and provide broad-spectrum protection against both UVA and UVB radiation.

Is systemic absorption of avobenzone harmful?

Systemic absorption of avobenzone has been documented, but the clinical significance is unclear. It is generally considered safe when used as directed, but further research is needed to fully understand its long-term effects.

Research Sources

https://pmc.ncbi.nlm.nih.gov/articles/PMC10059943/ – This article discusses the importance of sunscreen for preventing skin cancer and photoaging. It highlights the need for further research on the long-term effects of sunscreen ingredients, including avobenzone, due to their systemic absorption.
https://pmc.ncbi.nlm.nih.gov/articles/PMC7759112/ – This study investigated the systemic absorption of sunscreen ingredients, including avobenzone, under maximal use conditions. The findings indicated that avobenzone and other ingredients were absorbed systemically, exceeding FDA guidelines, suggesting a need for further safety evaluations.
https://www.scivisionpub.com/pdfs/sunscreens-percutaneous-absorption-and-ingredients-concentration-in-human-plasma-and-urine-a-systematic-review-2366.pdf – This systematic review examines the percutaneous absorption of sunscreen ingredients, including avobenzone, and their concentration in human plasma and urine. The review highlights the variability in absorption rates and the need for standardized testing methodologies to assess the safety of sunscreen ingredients.
https://pubs.acs.org/doi/10.1021/acs.langmuir.4c04108 – This research explores the use of β-cyclodextrin to enhance the photostability of avobenzone. The study demonstrates that incorporating avobenzone into β-cyclodextrin complexes can improve its stability and effectiveness as a UV filter in sunscreen formulations.
https://pubs.acs.org/doi/10.1021/acssuschemeng.0c02735 – This study investigates the use of sustainable materials to stabilize avobenzone in sunscreen formulations. The research focuses on developing environmentally friendly approaches to enhance the photostability and efficacy of avobenzone as a UV filter.