title: Fit of fluxes of sunscreens and other compounds from propylene glycol:water (30:70) through human skin and silicone membrane to the Roberts-Sloan equation: the effect of polar vehicle (or water) solubility.
abstract: It would be useful to develop a surrogate for animal skin, which could be use to predict flux through human skin. The fluxes (and physicochemical properties) of sunscreens and other compounds from propylene glycol (PG):water (AQ), 30:70, through human skin have previously been reported. We measured the fluxes of several of those sunscreens and other compounds from PG:AQ, 30:70, through silicone membrane and fit both sets of data to the Roberts-Sloan (RS) equation to determine any similarities. For both sets of data, the fluxes were directly dependent on their solubilities in a lipid solvent [octanol (OCT), in this case] and in a polar solvent (PG:AQ, 30:70, or AQ in this case) and inversely on their molecular weights. The fit of the experimental (EXP) fluxes through human skin in vivo to RS was excellent: r² = 0.92 if the vehicle (VEH) PG:AQ, 30:70 was the polar solvent (RS¹) or r² = 0.97 if water was the polar solvent (RS²). The fit of the EXP fluxes through silicone membrane to RS was good: r² = 0.80 if the VEH PG:AQ, 30:70, was the polar solvent (RS¹) or r² = 0.81 if water was the polar solvent (RS²). The correlations between their EXP fluxes through human skin in vivo and their EXP fluxes through silicone membrane were good (r² = 0.85). In addition, the correlation between EXP fluxes from PG:AQ, 30:70, through human skin in vivo and their fluxes calculated from the coefficients of the fit of solubilities, molecular weights and fluxes from water through silicone membranes from a previous n = 22 database to RS was even better (r² = 0.94). These results suggest that flux through human skin can be calculated from flux through a silicone membrane.
authors.affiliation: Department of Medicinal Chemistry, University of Florida, Gainesville, FL, USA. sloan@coop.ufl.edu
authors.forename: Kenneth B
authors.initials: KB
authors.lastname: Sloan
authors.forename: Hemamalini
authors.initials: H
authors.lastname: Devarajan-Ketha
authors.forename: Jennifer
authors.initials: J
authors.lastname: Synovec
authors.forename: Susruta
authors.initials: S
authors.lastname: Majumdar
mesh_terms: D006801:Humans; D019946:Propylene Glycol / Q000737:chemistry / Q000493:pharmacokinetics*; D012828:Silicones; D012867:Skin / Q000378:metabolism*; D012995:Solubility; D013473:Sunscreening Agents / Q000493:pharmacokinetics*; D014867:Water / Q000737:chemistry*
chemical_list: D012828:Silicones; D013473:Sunscreening Agents; D014867:Water; D019946:Propylene Glycol