In vitro/in vivo studies on a buccal bioadhesive tablet formulation of carbamazepine.

A buccoadhesive controlled-release system for delivery of carbamazepine (CBZ) was prepared by compression of hydroxypropyl methylcellulose (HPMC) and carbomer, incorporating a penetration enhancer, sodium glycodeoxycholate (GDC). The release behaviour of systems containing CBZ and various amounts of the two polymers with and without GDC was found to be non-Fickian. Formation of an interpolymer complex between HPMC and carbomer was confirmed in acidic medium by turbidity, viscosity and FT-IR measurements. Addition of the drug to the buccoadhesive formulation reduced the adhesion force significantly (p < 0.1). GDC did not have any effect on bioadhesion. Permeability of bovine buccal mucosa to CBZ was determined using Ussing diffusion chambers [1]. In vivo interaction between the tablet and tissue was examined histologically as well as by scoring mucosal irritation. Histological changes observed in the buccal epithelium after 4 h contact with the tablets containing GDC recovered completely within 24 h after removal. No measurable plasma level of CBZ was obtained either in the absence or presence of GDC.