Development of a Liposomal Dry Mouth Product for Long-Term Relief

Objectives: Most products on the market for the treatment of dry mouth have very limited and short-term effect. We aim to develop an ideal product for long-term relief of dry mouth, by combining mucoadhesive properties of biopolymers and moisturizing properties of liposomes. The first step is to assess the liposome-coating ability of three different biopolymers, and to evaluate stability over time, considering shelf life.
Methods: Cationic (SoyPC/DOTAP) and anionic (SoyPC/EggPG) liposomes were produced by the thin-film method in two concentrations (3 and 6mM), and hydrated with phosphate buffer (PB) or glycerol-phosphate buffer (G-PB). The liposomes were added to three specific biopolymer solutions of opposite charge, inducing spontaneous formation of chitosan-coated liposomes (CcLs), alginate-coated liposomes (AcLs) or gellan gum-coated liposomes (GcLs). Stability and precipitation were evaluated by size- and zeta potential measurements over time (t_CcL=8weeks, t_{AcL and GcL}=16weeks).
Results: Sizes of uncoated liposomes were between 120 and 135nm, whereas biopolymer-coated liposomes increased in size varying from 200 to 590nm (AcLsBoth AcLs and CcLs maintained sufficient stability in three of the four samples, while the GcLs only were stable in 3mM PB, as shown in Table 1. The zeta potential remained stable for all samples.
Conclusions: All three biopolymers showed good liposome-coating abilities. Alginate and chitosan are the most promising liposome-coating biopolymers demonstrating good stability, and will be focused upon in further studies regarding oral mucoadhesive properties and hydration effects.