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Stripping method to quantify absorption of two sunscreens in human
C Couteau1, N Perez Cullel, A E Connan
1Laboratory of Industrial Pharmacy, School of Pharmacy, University of Nantes, rue du Moulin de la Rousseliere-CP 4301-44805 cedex, Saint Herbiam, France.
International Journal of Pharmaceutics
|June 19, 2001
Summary
Benzophenone 4 shows better skin retention than PEG-25 PABA. Incorporating sunscreens into oil-in-water emulsions enhances their penetration, especially for benzophenone 4.
Area of Science:
- Cosmetic Science
- Dermatology
- Analytical Chemistry
Background:
- Sunscreens are crucial for photoprotection.
- Understanding sunscreen remanence on skin is vital for efficacy.
- PEG-25 PABA and benzophenone are common UV filters.
Purpose of the Study:
- To evaluate the skin remanence of PEG-25 PABA and benzophenone.
- To compare the retention of these filters in aqueous solutions versus oil-in-water (O/W) emulsions.
- To assess the influence of formulation on sunscreen penetration.
Main Methods:
- 21 women applied aqueous solutions and O/W emulsions containing PEG-25 PABA and benzophenone.
- Stratum corneum samples were collected via serial skin stripping (6 strippings).
- Sunscreen agent quantification was performed using High-Performance Liquid Chromatography (HPLC).
Main Results:
- Benzophenone 4 demonstrated superior remanence on the skin compared to PEG-25 PABA.
- Incorporation into O/W emulsions significantly promoted the penetration of both filters.
- Benzophenone 4 showed enhanced penetration when formulated in O/W emulsions.
Conclusions:
- Benzophenone 4 offers better and longer-lasting photoprotection due to its superior skin remanence.
- Oil-in-water emulsion formulations enhance sunscreen penetration, particularly for benzophenone 4.
- Formulation plays a key role in optimizing sunscreen delivery and efficacy.