Soluplus

Griseofulvin (GRI) (Ph. Eur. grade) was purchased from Fagron (Rotterdam, The Netherlands), and itraconazole (ITR) (Ph. Eur. grade) was purchased from Ria International India (Madurai, India). GRI and ITR belong to crystallization tendency class 1 and class 3, respectively [25 (link)]. This means that amorphous GRI crystallized in a DSC experiment during cooling before reaching the glass-transition temperature. In contrast, amorphous ITR neither crystallized during cooling below the glass-transition temperature nor during subsequent reheating to the melting point [25 (link)]. The polymers PVPVA (Plasdone S-630) with a molecular weight of 40,000 and Soluplus^® with a molecular weight of 118,000 g/mol were obtained from Ashland Inc. (Wilmington, DE, USA) and BASF (Ludwigshafen, Germany), respectively. Dichloromethane (purity > 98%) was purchased from VWR (Randor, PA, USA). All substances were used without further purification. Water used for long-term stability tests was filtered and deionized with a Merck Millipore purification system (Darmstadt, Germany). Figure 1 shows the chemical structures of the investigated compounds GRI, ITR, Soluplus^®_, and PVPVA.

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.