title: Influence of lipid microparticle encapsulation on in vitro efficacy, photostability and water resistance of the sunscreen agents, octyl methoxycinnamate and butyl methoxydibenzoylmethane.
abstract: BACKGROUND
  Essential requirements for the efficacy of sunscreen agents are optimal UV absorption, high photostability and resistance against water removal.
  
  
  OBJECTIVE
  Aim of this study was to investigate the effect of encapsulation in lipid microparticles (LMs) on the overall performance of the two most commonly used sunscreen agents, octyl methoxycinnamate (OMC) and butyl methoxydibenzoylmethane (BMDBM).
  
  
  METHODS
  LMs loaded with OMC and BMDBM were prepared by melt emulsification and characterized by optical microscopy, UV filter content and release studies. The LMs incorporating OMC and BMDBM or the nonencapsulated sunscreen agents were introduced into a model cream (oil-in-water emulsion).
  
  
  RESULTS
  No significant differences were observed between the sun protection factor (SPF) of the formulations containing the free (SPF, 9.4 ± 1.9) or microencapsulated (SPF, 9.6 ± 1.3) UV filters. Irradiation of the creams with a solar simulator demonstrated that the photodecomposition of OMC and BMDBM was significantly decreased by encapsulation in LMs from 55.7 ± 5.3% to 46.1 ± 5.1% and 36.3 ± 3.9% to 20.1 ± 4.7%, respectively. However, in vitro water-resistance studies showed that entrapment in the LMs significantly enhanced the sunscreen agent removal caused by watering (the losses for OMC and BMDBM were 45.1 ± 6.3% and 49.2 ± 8.4%, respectively), as compared to the formulation with the nonencapsulated sunscreen agents (the losses for OMC and BMDBM were 26.7 ± 6.1% and 28.0 ± 6.7%, respectively).
  
  
  CONCLUSIONS
  Incorporation in LMs can have controversial effects on UV filter efficacy. In particular, the water-resistance properties of sun-care formulations containing sunscreens loaded in LMs should be verified to assure that the photoprotective activity is maintained during usage.
authors.affiliation: Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Ferrara , Ferrara , Italy and.
authors.forename: Valentina
authors.initials: V
authors.lastname: Trotta
authors.forename: Filipa
authors.initials: F
authors.lastname: Goios
authors.forename: Helena
authors.initials: H
authors.lastname: Monteiro
authors.forename: Isabel F
authors.initials: IF
authors.lastname: Almeida
authors.forename: Santo
authors.initials: S
authors.lastname: Scalia
mesh_terms: D000473:Alkanes / Q000737:chemistry*; D047188:Chalcones / Q000737:chemistry*; D002626:Chemistry, Pharmaceutical / Q000379:methods; D002934:Cinnamates / Q000737:chemistry*; D004339:Drug Compounding / Q000379:methods; D004355:Drug Stability; D004655:Emulsions / Q000737:chemistry; D008055:Lipids / Q000737:chemistry*; D011427:Propiophenones; D059405:Sun Protection Factor / Q000379:methods; D013473:Sunscreening Agents / Q000737:chemistry*; D014466:Ultraviolet Rays / Q000009:adverse effects; D014867:Water / Q000737:chemistry*
chemical_list: D000473:Alkanes; D047188:Chalcones; D002934:Cinnamates; D004655:Emulsions; D008055:Lipids; D011427:Propiophenones; D013473:Sunscreening Agents; D014867:Water; C118580:octylmethoxycinnamate; C049935:avobenzone
keywords: Emulsion; UV filters; in vitro sun protection factor; microencapsulation; photodegradation; water exposure