Mucoadhesive delivery systems. I. Evaluation of mucoadhesive polymers for buccal tablet formulation

Different types of mucoadhesive polymers, intended for buccal tablet formulation, were investigated for their comparative mucoadhesive force, swelling behavior, residence time and surface pH. The selected polymers were carbopols (CP934, and CP940), polycarbophil (PC), sodium carboxymethyl cellulose (SCMC) and pectin representing the anionic type, while chitosan (Ch) as cationic polymer and hydroxypropylmethyl cellulose (HPMC) as a non-ionic polymer. Results revealed that polyacrylic acid derivatives (PAA) showed the highest bioadhesion force, prolonged residence time and high surface acidity. SCMC and chitosan ensured promising bioadhesive characteristics, whilst HPMC and pectin exhibited weaker bioadhesion. Different polymer combinations as well as formulations were evaluated to improve the mucoadhesive performance of the tablets. Bioadhesive tablet formulations containing either 5% CP934, 65% HPMC and 30% spray-dried lactose or 2% PC, 68% HPMC and 30% mannitol showed optimum mucoadhesion and suitable residence time. SCMC, when formulated individually, exhibited promising bioadhesion, acceptable swelling, convenient residence time and surface pH. In-vivo trials of these formulations proved non-irritative and prolonged residence of the mucoadhesive tablets on human buccal mucosa for 8 to 13 h.