Compressed Medicated Chewing Gum with Lysozyme Hydrochloride and Ascorbic Acid for Xerostomia Relief and Oral Health Support: Formulation Development, Optimization, In Vitro and In Vivo Evaluation

Background: Existing therapies for xerostomia are primarily symptomatic, providing temporary mucosal hydration without addressing underlying pathological changes in the oral cavity. In this context, medicated chewing gums containing ascorbic acid and lysozyme hydrochloride offer a promising approach, combining antimicrobial, antioxidant, and trophic effects with physiological salivary stimulation and prolonged local delivery. Methods: For the development of compressed chewing gum formulation, the physicochemical (particle size distribution, moisture absorption capacity, and microscopic characteristics) and technological (flowability, angle of repose, bulk and tapped density, Carr’s index (CI), and Hausner ratio (HR)) properties of the active substances and their formulations with excipients were evaluated. Pharmacological activity was assessed in an atropine-induced xerostomia rat model. Results: The physical mixture of all components showed inferior flow properties compared with the formulation containing pre-granulated lysozyme hydrochloride, as evidenced by higher Carr’s index and Hausner ratio values (CI = 17, HR = 1.20 vs. CI = 13, HR = 1.14), indicating improved processability after pre-granulation. The effect of relative humidity during formulation was also assessed, with an optimal level of 40% required to ensure process stability due to the hygroscopic nature of the components. Based on these data, technological approaches ensuring processability were established, including wet pre-granulation of lysozyme hydrochloride and premixing of ascorbic acid to reduce oxidation risk. These approaches resulted in an optimized compression mass with excellent flowability (CI = 8, HR = 1.09), suitable for the preparation of medicated chewing gum. An optimal compression force (7 kN) ensured suitable rheological and textural properties, resulting in rapid and nearly complete release of the active ingredients from the medicated chewing gum, consistent with kinetic analysis. In vivo studies using an atropine-induced xerostomia rat model demonstrated that the combination of ascorbic acid and lysozyme hydrochloride significantly increased salivary secretion (2.17-fold vs. control pathology group) and reduced salivary gland mass coefficients (by 13–18% compared with the control pathology group and groups receiving individual active ingredients), alongside improvement of oxidative stress markers, including a reduction in TBA-reactants (by 51.6%) and an increase in catalase activity (by 51.0%). Conclusions: The developed medicated chewing gum showed favorable technological properties, efficient release of active ingredients, and anti-xerostomic activity in vivo, indicating its potential for xerostomia relief and oral health support.