Adhesive Properties of Natural Polymers Commonly Used in Oral Dosage Forms

Objective:Investigate in vitro adhesive properties of natural polymers commonly used in the formulation of mucoadhesive dosage forms. Background:Extending the release of a drug can extend its half-life hence its effect and it can be achieved by increasing retention of the dosage form in the body. Several polymeric excipients are used to increase drug retention in the gastrointestinal tract by adhering to the mucosal membrane. Studying adhesive properties of such polymeric excipients helps optimize adhesion and thus the retention of the drugs. Methods:Oral films of sodium alginate, sodium carboxymethylcellulose (CMC) and chitosan at various polymer contents (0.5-3.0%) were prepared by solvent casting method (40°C, 24 hr). Adhesive force was measured using Texture Analyzer(CT3) in compression mode in the presence of artificial saliva (pH6.8). Maximum negative force recorded by the TextureProCT(V1.4) software was reported as the adhesive force. Results:CMC showed the highest adhesion while chitosan showed almost no adhesive properties. This could be due to the pH dependent solubility of chitosan as it is only soluble in acidic media. Our results also show lower polymer contents result in increased adhesive forces. This is due to higher saliva/polymer ratio, which results in faster film hydration and subsequently stronger adhesion. This is confirmed by increasing the contact time of the polymer with the substrate when high solid films are used. Conclusion:Among tested polymers, CMC showed highest adhesion. Furthermore, the adhesive force increases as the polymer content of the films decreases due to the faster hydration rate. Grants: This study was supported by NSU Grant335114.