Thiomers: potential excipients for non-invasive peptide delivery systems

Synthesis, characterisation and in vitro evaluation of novel thiolated derivatives of polyallylamine and quaternised polyallylamine

“…[30]. The reaction was also carried out under nitrogen and at pH 4.5 to limit air or pH-induced oxidation of thiol groups to the reactive thiolate anion S -resulting in the formation of intramolecular disulphide bond formation [31]. An N-acylated amino acid was used during the reaction to prevent the occurrence of unwanted side reactions resulting in the formation of oligo/poly cysteine conjugates [27].…”

Novel Mucoadhesive Polymers for Nasal Drug Delivery

“…It also has the ability to form hydrogen bonds with sugar moieties on glycosylated proteins. This causes PEG to form strong bonds with mucus leading to increased mucoadhesion [25].…”

“…First the synthesis of alginate thiol takes place. In the second stage, a Michael type addition reaction takes place where a nucleophilic addition between PEG-Diacrylate and alginate backbone occurs conjugating the two [25].…”

“…Addition of PEG results in H-bonding with PAA enhancing the viscosity of the resulting drug delivery vehicle. Addition of PEG to the polymer increases the viscosity of the resulting polymer complex retarding disintegration and removal of the polymer from the mucosal surface thus increasing mucoadhesion [30]. The combination of the three functional moieties of Alginate Polyethylene glycol Acrylate leads to an improved novel polymer that can be used mucoadhesive nasal drug delivery.…”

Insulin delivery through nasal route using thiolated microspheres

“…The enhancement of mucoadhesion can be explained by the formation of covalent bonds between the polymer and the mucus layer, which are stronger than noncovalent bonds. These thiomers are supposed to interact with cysteine rich subdomains of mucus glycoproteins via disulfide exchange reactions (Lehr, 1996;Bernkop-Schnürch et al, 1999;Bernkop-Schnürch et al, 2004).…”