title: Thiolated polymers: evaluation of their potential as dermoadhesive excipients.
abstract: The objective of this study was to evaluate and compare four different thiolated polymers regarding their dermoadhesive potential. Therefore, three hydrophilic polymers (poly(acrylic acid), Carbopol 971 and carboxymethylcellulose) and a lipophilic polymer (silicone oil) were chosen to generate thiolated polymers followed by characterization. The total work of adhesion (TWA) and the maximum detachment force (MDF) of formulations containing modified and unmodified polymers were investigated on skin obtained from pig ears using a tensile sandwich technique. The synthesis of thiolated polymers provided 564 µmol, 1079 µmol, 482 µmol and 217 µmol thiol groups per gram poly(acrylic acid), Carbopol 971, carboxymethylcellulose and silicone oil, respectively. Hydrogels containing poly(acrylic acid)-cysteine, Carbopol 971-cysteine, and carboxymethylcellulose-cysteamine exhibited a 6-fold, 25-fold and 9-fold prolonged adhesion on porcine skin than the hydrogel formulations prepared from the corresponding unmodified polymers, respectively. Furthermore, thiolation of silicone oil with thioglycolic acid led to a 5-fold improvement in adhesion compared to the unmodified silicone oil. A comparison between the four thiolated polymer formulations showed a clear correlation between the amount of coupled thiol groups and the TWA. According to these results thiomers might also be useful excipients to provide a prolonged dermal resistance time of various formulations.
authors: a ThioMatrix GmbH, Research Center Innsbruck , Innsbruck , Austria.
authors: Julia Anita
authors: JA
authors: Grießinger
authors: b Department of Pharmaceutical Technology , Center for Chemistry and Biomedicine, Institute of Pharmacy, University of Innsbruck , Innsbruck , Austria.
authors: Sonja
authors: S
authors: Bonengel
authors: b Department of Pharmaceutical Technology , Center for Chemistry and Biomedicine, Institute of Pharmacy, University of Innsbruck , Innsbruck , Austria.
authors: Alexandra
authors: A
authors: Partenhauser
authors: b Department of Pharmaceutical Technology , Center for Chemistry and Biomedicine, Institute of Pharmacy, University of Innsbruck , Innsbruck , Austria.
authors: Muhammad
authors: M
authors: Ijaz
authors: b Department of Pharmaceutical Technology , Center for Chemistry and Biomedicine, Institute of Pharmacy, University of Innsbruck , Innsbruck , Austria.
authors: Andreas
authors: A
authors: Bernkop-Schnürch
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry* / Q000378:metabolism; D000269:Adhesives / Q000737:chemistry*; D000279:Administration, Cutaneous; D000818:Animals; D002266:Carboxymethylcellulose Sodium; D003545:Cysteine / Q000031:analogs & derivatives* / Q000737:chemistry; D016503:Drug Delivery Systems; D005079:Excipients / Q000737:chemistry*; D020100:Hydrogels / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D000180:Acrylic Resins; D000269:Adhesives; D005079:Excipients; D020100:Hydrogels; D013438:Sulfhydryl Compounds; C000620832:poly(acrylic acid)-cysteine; C006903:carbopol 940; D002266:Carboxymethylcellulose Sodium; D003545:Cysteine
keywords: Hydrophilic thiomers; bioadhesion; dermoadhesion; hydrogel; lipophilic thiomers; skin application; tensile apparatus