The Influence of Various Mucoadhesive Polymers on In Vitro Performance of the Resulting Artificial Saliva Pump Spray Formulations

The aim of this study was to investigate the rheological behavior and mucoadhesive nature of saliva substitutes, by incorporating various mucoadhesive polymers into an artificial saliva pump spray formulation. For this purpose various mucoadhesive polymers including cellulosic polymers in the range of 0.1-1.0% and Carbomers such as C974p, C971, C934p and C971 in the range of 0.01-0.1% were added to a formulated aqueous-based artificial saliva pump spray formulation, containing fixed amounts of some essential electrolytes. The pH of the formulations was between 6.3-7.4. The formulations were examined in terms of appearance, taste, odor, spray-ability, short-term thermal and mechanical stability, pH, viscosity and rheological behavior, particle size distribution, as well as invitro mucoadhesive strength (MS). The mucoadhesivity ratio (MR) was also calculated as follows: MR=MS_test/MS_control, using natural saliva as the control. Natural saliva showed a pseudoplastic rheological behavior, with a viscosity in the range of 12.85-28.15cP. Hence, artificial saliva samples having viscosities within this range were selected. The rheological behavior and viscosity of the test samples as well as the natural saliva were subsequently determined. Similar to that found for the natural saliva, all the prepared formulations showed a pseudoplastic rheological behavior. Among the polymers, C974p had the highest viscosity (25.97±0.11 cP) and mucoadhesive strength (34.84±0.21 mN/cm²) followed by hydroxypropylmethylcellulose which had a viscosity of 25.48±0.11 cP and a mucoadhesive strength of 34.03±0.24 mN/cm². Furthermore, the mucoadhesivity of C974p containing artificial saliva was 1.186 times greater than natural saliva and 1.387 times more than water. In conclusion, it seems that the presence of mucoadhesive polymers within the artificial saliva pump spray formulations could help to improve the adhesive nature of the formulation to mucosal surfaces, making it even more effective than the natural saliva.