Encapsulation of the UV Filters Ethylhexyl Methoxycinnamate and Butyl Methoxydibenzoylmethane in Lipid Microparticles: Effect on in vivo Human Skin Permeation

Abstract

Background: Lipid microparticles loaded with the UVB filter ethylhexyl methoxycinnamate (EHMC) and the UVA filter butyl methoxydibenzoylmethane (BMDBM) were evaluated for their effect on the sunscreen agent’s percutaneous penetration. Methods: Microparticles loaded with EHMC or BMDBM were prepared by the melt emulsification technique using stearic acid or glyceryl behenate as lipidic material, respectively, and hydrogenate phosphatidylcholine as the surfactant. Nonencapsulated BMDBM and EHMC in conjunction with blank microparticles or equivalent amounts of the 2 UV filters loaded in the lipid microparticles were introduced into oil-in-water emulsions and applied to human volunteers. Skin penetration was investigated in vivo by the tape-stripping technique. Results: For the cream with the nonencapsulated sunscreen agents, the percentages of the applied dose diffused into the stratum corneum were 32.4 ± 4.1% and 30.3 ± 3.3% for EHMC and BMDBM, respectively. A statistically significant reduction in the in vivo skin penetration to 25.3 ± 5.5% for EHMC and 22.7 ± 5.4% for BMDBM was achieved by the cream containing the microencapsulated UV filters. The inhibiting effect on permeation attained by the lipid microparticles was more marked (45–56.3% reduction) in the deeper stratum corneum layers. Conclusions: The reduced percutaneous penetration of BMDBM and EHMC achieved by the lipid microparticles should preserve the UV filter efficacy and limit potential toxicological risks.

Comparative Evaluation of the Effect of Permeation Enhancers, Lipid Nanoparticles and Colloidal Silica on in vivo Human Skin Penetration of Quercetin

“…An emulsion with 10% water instead of DGME served as control formulation. The penetration of quercetin into human skin was studied in vivo using the tape stripping technique, based on the progressive removal of the stratum corneum outer layers by sequential stripping with adhesive tapes [29,30,36]. The amount of quercetin transferred to the individual tape strips following topical application of the tested formulations was quantified to provide the in vivo stratum corneum penetration profile of the flavonoid.…”

“…The creams were homogeneously distributed using rubber gloves. After an application time of 60 min [30], the remaining preparation was removed from the treated area by a cotton swab, and then the stratum corneum was sequentially stripped 15 times with Scotch transparent adhesive tapes [30,36,37]. The tapes were applied to the skin with a constant pressure by a 500 g stainless steel roller (30 mm diameter).…”

“…In order to overcome this problem, in this study the skin penetration of the flavonoid was assessed in vivo on human volunteers using a noninvasive procedure, namely the tape-stripping technique, based on the progressive removal of the outer stratum corneum layers with adhesive tapes [29,30]. The effect of different topical vehicles on the in vivo percutaneous permeation of quercetin was investigated.…”

Analysing the Skin Barrier from Down Under

“…Mike's group also showed that sunscreen products designed and marketed for application to children did not reduce sunscreen permeation compared to general-purpose sunscreen formulations [44]. These reports led to increased interest in the reformulation of sunscreen products to optimize activity at the skin surface and minimize skin penetration and systemic absorption both by Mike's group [45,46,47,48] and others [48,49,50,51]. …”

Drug Delivery with Topically Applied Nanoparticles: Science Fiction or Reality?

“…Likewise for solid nanoparticles, the penetration pathways are still a topic of intensive investigation. In intact skin, it was demonstrated that topically applied solid nanoparticles are located only on the skin surface or within the upper lipid layers of the stratum corneum [15,16]. From here, the nanoparticles can be rapidly removed by washing processes, by textile contact or by desquamation [17].…”