In vitro Fluoride Release and Tensile Bond Strength of a Polymeric Intra-Buccal Bioadhesive

A potential tailor-made hyaluronic acid buccal delivery system comprising rotigotine for Parkinson's disease?

Aims: Parkinson's disease (PD) affects over 10 million people around the world. Dysphagia is one of its main problems. Therefore, mucosal delivery is beneficial for patient compliance. This study aimed to synthesize mucoadhesive hyaluronic acid (HA) comprising rotigotine for the treatment of PD. Materials & methods: HA – a biocompatible, naturally occurring polysaccharide – was chemically modified with the thiol-bearing ligand cysteine ethyl ester via amide bond formation (HAC). HAC was evaluated in terms of stability, cytotoxicity, permeation enhancement, controlled drug release and mucoadhesiveness. Results: HAC showed 1.49-fold higher stability, 3.47-fold improved swelling capacity and 12.16-fold augmentation in mucoadhesion. Additionally, HAC exhibited 1.18-fold permeation enhancement over HA. Discussion: Taking the findings into consideration, HAC represents a pillar of mucosal buccal delivery in the treatment of PD.

Surfactants modify the release from tablets made of hydrophobically modified poly (acrylic acid)

Many novel pharmaceutically active substances are characterized by a high hydrophobicity and a low water solubility, which present challenges for their delivery as drugs. Tablets made from cross-linked hydrophobically modified poly (acrylic acid) (CLHMPAA), commercially available as Pemulen™, have previously shown promising abilities to control the release of hydrophobic model substances. This study further investigates the possibility to use CLHMPAA in tablet formulations using ibuprofen as a model substance. Furthermore, surfactants were added to the dissolution medium in order to simulate the presence of bile salts in the intestine.

The release of ibuprofen is strongly affected by the presence of surfactant and/or buffer in the dissolution medium, which affect both the behaviour of CLHMPAA and the swelling of the gel layer that surrounds the disintegrating tablets. Two mechanisms of tablet disintegration were observed under shear, namely conventional dissolution of a soluble tablet matrix and erosion of swollen insoluble gel particles from the tablet. The effects of surfactant in the surrounding medium can be circumvented by addition of surfactant to the tablet. With added surfactant, tablets that may be insusceptible to the differences in bile salt level between fasted or fed states have been produced, thus addressing a central problem in controlled delivery of hydrophobic drugs. In other words CLHMPAA is a potential candidate to be used in tablet formulations for controlled release with poorly soluble drugs.