Objectives: This study evaluated the comfort of using silicone tubes installed in the oral cavity as a reservoir for a hydrogel that allows for a slow delivery of the active substance acting locally or systemically. Methods: Perforated silicone tubes 8 cm long with two internal diameters were used: T1 (1.5 mm) and T2 (2.4 mm). The reservoirs were filled with hydrogel placebo formulations: carbomer 1.5% (C), hydroxyethylcellulose 4% (HEC), or hydroxypropylmethylcellulose (hypromellose) 3% (HPMC). Physical parameters of the gel were determined with a viscometer and a texture analyzer. During 4 h of application, the volunteers reported sensory perceptions, and the rate of gel erosion was evaluated. The results were correlated with the viscosity, rheology, and dissolution rate of the gels measured in vitro. Results: Volunteers reported only mild discomfort wearing the device, preferring smaller-sized tubes. The tubes were easy to apply and generally comfortable, with no reports of significant discomfort. Despite similar viscosity and rheology, the polymer type had a significant impact on erosion rate, both in vitro and in vivo. After 4 h of application in vivo, more than 90% of the carbomer gel remained in the tube, while in the case of less cohesive HPMC or HEC gels, this was about 50%. A statistically significant correlation was observed between the in vitro and in vivo mean erosion percentages for the HEC and HPMC gels. Conclusions: This study supports the use of silicone tubes as effective reservoir devices for prolonging the residence time of drug formulations in the oral cavity.
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