Transdermal delivery of NAR

NAR ((2S)-5,7-dihydroxy-2-(4-hydroxyphenyl)-2,3-dihydro-4H-chromen-4-one, purity ≥ 98%, lot MKCD1056) was obtained from Sigma-Aldrich (St. Louis, MO, USA). The polymer Parteck^® MXP (PVA, polyvinyl alcohol, lot F1952064) was donated by Merck (Darmstadt, Germany). Klucel^TM EF (HPC, hydroxypropylcellulose, lot 40915) and Soluplus^® (SOL, polyvinyl-caprolactam-polyvinyl-acetate-polyethyleneglycol, lot 844143368EO) were donated by Ashland Specialty Ingredients (Covington, LA, USA) and BASF (Ludwigshafen, Germany), respectively. Glycerin (GLY, lot 58591) and Tween 80 (polysorbate, lot 105896) were obtained from Dinâmica^® (Sao Paulo, Brazil). Skin from porcine ears was obtained from a local slaughterhouse (Via Carnes Indústria e Comércio, Brasilia, Brazil). The whole skin was removed from the outer region of the ear, separated from its underlying layer, and used full thickness.