In vivo evaluation of anionic thiolated polymers as oral delivery systems for efflux pump inhibition.

Recently, the cationic polymer thiolated chitosan has been reported to modulate drug absorption by inhibition of intestinal efflux pumps. The objective of this study was to evaluate in vitro and in vivo whether thiolated anionic biopolymers also show an efflux pump inhibitory effect in order to improve intestinal transcellular drug uptake. Therefore, three thiomers have been synthesized due covalent attachment of cysteine to various polymer backbones: pectin-cysteine (pect-cys), carboxymethylcellulose-cysteine (CMC-cys) and alginate-cysteine (alg-cys).

Safety assessment of thiolated polymers: effect on ciliary beat frequency in human nasal epithelial cells.

Objective: The aim of this study was to investigate the nasal safety of gel formulations of thiolated polymers (thiomers) by assessing their effect on ciliary beat frequency (CBF) in human nasal epithelial cells.

Methods: Poly(acrylic acid) 450 kDa-cysteine (PAA-cys) and alginate-cysteine (alg-cys) were synthesized by covalent attachment of L-cysteine to the polymeric backbone. The cationic polymer chitosan-thiobutylamidine (chito-TBA) was synthesized by attaching iminothiolane to chitosan.

Insulin-loaded poly(acrylic acid)-cysteine nanoparticles: stability studies towards digestive enzymes of the intestine.

This study evaluated thiolated poly(acrylic acid) nanoparticles as a valuable tool to protect insulin from degradation by serinproteases of the intestine. Nanaoparticles were characterized concerning particle size, zeta potential, and drug load. Furthermore, in vitro release studies were performed.

Development and in vitro evaluation of a mucoadhesive vaginal delivery system for nystatin.

The purpose of the present study was to design and evaluate a novel vaginal delivery system for nystatin based on mucoadhesive polymers. L-Cysteine and cysteamine, respectively, were covalently attached to poly(acrylic acid), and the two different thiolated polymers were evaluated in vitro regarding their swelling behavior, mucoadhesive properties and release behavior. Tablets comprising these thiolated polymers and nystatin demonstrated a high stability in vaginal fluid simulant pH 4.

Thiolated chitosan: development and in vitro evaluation of an oral delivery system for acyclovir.

The aim of the study was to develop a novel oral delivery system for the efflux pump substrate acyclovir (ACY) utilizing thiolated chitosan as excipient which is capable of inhibiting P-glycoprotein (P-gp). Three chitosan-4-thiobutylamidine (Chito-TBA) conjugates with increasing molecular mass (Chito-9.4kDa-TBA, Chito-150kDa-TBA and Chito-600kDa-TBA) were synthesized and permeation studies on rat intestinal mucosa and Caco-2 monolayers were performed.

Synthesis and characterization of a chitosan-N-acetyl cysteine conjugate.

The aim of the present study was to synthesize and characterize a novel thiolated polymer by covalent attachment of N-acetyl cysteine to chitosan. The obtained conjugate was characterized in vitro by quantification of immobilized thiol groups and their pH dependent oxidation, swelling behaviour in artificial intestinal fluid at pH 6.8, rheological properties and evaluation of its mucoadhesive properties on freshly excised porcine mucosa.

Thiolated polymers: evaluation of the influence of the amount of covalently attached L-cysteine to poly(acrylic acid).

It was the aim of this study to investigate the influence of the amount of thiol groups being covalently attached to poly(acrylic acid) 450 kDa on its properties. Five different PAA(450)-L-cysteine conjugates (PAA(450)-Cys) were synthesized bearing 53.0 (PAA I), 113.