Xerostomia is a common condition, especially among older adults, cancer patients, and people taking large amounts of medications. Researchers at the University of Leeds have developed a saliva substitute to ease the discomfort of patients suffering from dry mouth. The new solution mimics natural saliva in its ability to moisturize the mouth and serve as a lubricant during meals. It contains dairy or vegan proteins and laboratory experiments have already shown that it is more effective than other commercially available products.
According to a 2018 systematic review, xerostomia affects approximately 22% of the world's population and can lead to serious complications. There are many physical, emotional and social consequences of xerostomia. The global increase in the incidence of xerostomia in recent years has been attributed to the increased polypharmacy and use of cancer-related radiation therapy, as well as the increasing incidence of chronic, neurodegenerative and autoimmune diseases such as Sjögren's syndrome, coupled with the aging population, a major global demographic trend.
Despite the availability of a wide range of saliva substitutes, they do not relieve xerostomia for a sufficient period of time. Professor of colloids and surface sciences Anwesha Sarkar, who led the development of the saliva substitute in the university's School of Food Sciences and Dietetics, commented in a press release: “The problem with many existing commercial products is that they are only effective for a short period of time because they do not interact with surface of the mouth, and people have to reapply the product frequently, sometimes while talking or eating. It affects people's quality of life.”
The newly developed saliva substitute, a microgel-enhanced hydrogel-based lubricant, was tested on eight existing commercial products, including well-known brands such as GSK's Biotène, Fresenius Kabi's Glandosane, Wyvern Medical's Saliveze and Oralieve. The experiments were carried out on an artificial surface similar to a tongue.
The study found that this saliva substitute provided significantly improved boundary lubrication, being 41-99% more effective against liquids and viscous substances compared to existing products. This result is primarily due to its adsorption properties, which allow it to bind more effectively to oral surfaces. In contrast to the 23-58% desorption rate observed with commercial alternatives, the new saliva substitute demonstrated a markedly lower desorption rate of 7%. Additionally, the research team noted that the milk protein formulation performed slightly better than its vegan counterpart.
Lead author of the study, Dr Olivia Pabua, a research fellow at the university, stressed that the trial results provide strong proof of concept that their material is likely to be more effective in real-world conditions and can provide relief for up to five times longer than existing products available.
Benchmarking results show favorable results in three key areas. This microgel provides high hydration, binds firmly to the oral surface and is an effective lubricant, making people more comfortable eating and speaking.
The first recipe of the new solution is based on milk protein, and the vegan version is based on potato protein. The substances used in the production of the saliva substitute are non-toxic and non-caloric.
Graphic representation of the structure of a milk-based lubricant (left) and a vegan version (right). The hydrated microgel proteins (dark blue and dark green network structures) are partially covered by a hydrogel made from a polysaccharide.
The study had several limitations. Although the study measured lubricity under oral conditions, it did not evaluate the long-term hydration performance of the newly developed lubricant compared to competing products. In addition, it must be taken into account that the temperature of the ingested foods could potentially affect the lubricity of the saliva substitute.
The study authors aim to develop the new saliva substitute into commercially available products, intending to improve the quality of life for people suffering from complex dry mouth conditions. In summary, this extensive comparative study lays the foundation for the use of these microgel-based aqueous lubricant formulations as an innovative approach to the treatment of xerostomia.