title: 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.
authors.affiliation: Department of Pharmaceutical Sciences, University of Ferrara, Ferrara, Italy. sls@unife.it
authors.forename: S
authors.initials: S
authors.lastname: Scalia
authors.forename: M
authors.initials: M
authors.lastname: Mezzena
authors.forename: D
authors.initials: D
authors.lastname: Ramaccini
mesh_terms: D000328:Adult; D000473:Alkanes / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics*; D047188:Chalcones / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics*; D002934:Cinnamates / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics*; D004339:Drug Compounding; D004655:Emulsions / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D008081:Liposomes / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics; D008863:Microspheres; D010316:Particle Size; D011427:Propiophenones; D012867:Skin / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D012869:Skin Absorption / Q000187:drug effects*; D013473:Sunscreening Agents / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics; D014466:Ultraviolet Rays; D055815:Young Adult
chemical_list: D000473:Alkanes; D047188:Chalcones; D002934:Cinnamates; D004655:Emulsions; D008081:Liposomes; D011427:Propiophenones; D013473:Sunscreening Agents; C516303:ethylhexyl methoxycinnamate; C049935:avobenzone