title: In vivo and in vitro evaluation of octyl methoxycinnamate liposomes.
abstract: Solar radiation causes damage to human skin, and photoprotection is the main way to prevent these harmful effects. The development of sunscreen formulations containing nanosystems is of great interest in the pharmaceutical and cosmetic industries because of the many potential benefits. This study aimed to develop and evaluate an octyl methoxycinnamate (OMC) liposomal nanosystem (liposome/OMC) to obtain a sunscreen formulation with improved safety and efficacy by retaining OMC for longer on the stratum corneum.
  
  
  METHODS
  The liposome/OMC nanostructure obtained was tested for enzymatic hydrolysis with lipase from Rhizomucor miehei and biodistribution with liposomes labeled with technetium-99m. The liposome/OMC formulation was then incorporated in a gel formulation and tested for ocular irritation using the hen's egg test-chorio-allantoic membrane (HET-CAM) assay, in vitro and in vivo sun protection factor, in vitro release profile, skin biometrics, and in vivo tape stripping.
  
  
  RESULTS
  The liposome/OMC nanosystem was not hydrolyzed from R. miehei by lipase. In the biodistribution assay, the liposome/OMC formulation labeled with technetium-99m had mainly deposited in the skin, while for OMC the main organ was the liver, showing that the liposome had higher affinity for the skin than OMC. The liposome/OMC formulation was classified as nonirritating in the HET-CAM test, indicating good histocompatibility. The formulation containing liposome/OMC had a higher in vivo solar photoprotection factor, but did not show increased water resistance. Inclusion in liposomes was able to slow down the release of OMC from the formulation, with a lower steady-state flux (3.9 ± 0.33 μg/cm(2)/hour) compared with the conventional formulation (6.3 ± 1.21 μg/cm(2)/hour). The stripping method showed increased uptake of OMC in the stratum corneum, giving an amount of 22.64 ± 7.55 μg/cm(2) of OMC, which was higher than the amount found for the conventional formulation (14.57 ± 2.30 μg/cm(2)).
  
  
  CONCLUSIONS
  These results indicate that liposomes are superior carriers for OMC, and confer greater safety and efficacy to sunscreen formulations.
authors.affiliation: Faculty of Pharmacy, Federal University of Rio de Janeiro.
authors.forename: Aline de Carvalho Varjão
authors.initials: Ade C
authors.lastname: Mota
authors.affiliation: Faculty of Pharmacy, Federal University of Rio de Janeiro.
authors.forename: Zaida Maria Faria
authors.initials: ZM
authors.lastname: de Freitas
authors.affiliation: Faculty of Pharmacy, Federal University of Rio de Janeiro.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Ricci Júnior
authors.affiliation: Faculty of Pharmacy, Federal University of Rio de Janeiro.
authors.forename: Gisela Maria
authors.initials: GM
authors.lastname: Dellamora-Ortiz
authors.affiliation: Nuclear Engineering Institute, National Nuclear Energy Commission.
authors.forename: Ralph
authors.initials: R
authors.lastname: Santos-Oliveira
authors.affiliation: Allergisa Dermatocosmetic Research, University of Campinas, São Paulo.
authors.forename: Rafael Antonio
authors.initials: RA
authors.lastname: Ozzetti
authors.affiliation: Allergisa Dermatocosmetic Research, University of Campinas, São Paulo.
authors.forename: André Luiz
authors.initials: AL
authors.lastname: Vergnanini
authors.affiliation: Pharmacology and Toxicology Department, National Insitute of Quality Control in Health, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil.
authors.forename: Vanessa Lira
authors.initials: VL
authors.lastname: Ribeiro
authors.affiliation: Pharmacology and Toxicology Department, National Insitute of Quality Control in Health, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil.
authors.forename: Ronald Santos
authors.initials: RS
authors.lastname: Silva
authors.affiliation: Faculty of Pharmacy, Federal University of Rio de Janeiro.
authors.forename: Elisabete Pereira
authors.initials: EP
authors.lastname: dos Santos
mesh_terms: D000328:Adult; D000818:Animals; D002934:Cinnamates / Q000737:chemistry / Q000493:pharmacokinetics*; D005260:Female; D006801:Humans; D006868:Hydrolysis; D008081:Liposomes / Q000737:chemistry / Q000493:pharmacokinetics*; D008875:Middle Aged; D015609:Organotechnetium Compounds / Q000737:chemistry / Q000493:pharmacokinetics*; D051381:Rats; D017208:Rats, Wistar; D012867:Skin / Q000737:chemistry; D013473:Sunscreening Agents / Q000737:chemistry / Q000493:pharmacokinetics*; D053832:Surgical Tape; D014018:Tissue Distribution; D055815:Young Adult
chemical_list: D002934:Cinnamates; D008081:Liposomes; D015609:Organotechnetium Compounds; D013473:Sunscreening Agents; C118580:octylmethoxycinnamate
keywords: lipase; liposome; sunscreen; tape stripping; technetium-99-m