Human buccal absorption of flurbiprofen.

The buccal absorption of flurbiprofen was studied in normal men to quantify the transport from the oral cavity in humans and to evaluate the closed-perfusion cell apparatus as a means to study drug transport across externally accessible biologic membranes. Flurbiprofen was buccally absorbed by a passive diffusional mechanism and the rate of absorption was pH dependent. Membrane permeability coefficients for flurbiprofen were 4.3 x 10(-4) cm/sec at pH 5.5 and 2.1 x 10(-5) cm/sec at pH 7.0. These findings are in agreement with the pH relationship for buccal transport observed in dog experiments. Delineation of the effective permeability coefficients into components for the aqueous boundary layer and the lipoidal buccal membrane allowed for the prediction of the extent of absorption of the drug over a period of time. It was concluded that the buccal membranes of the human and dog were essentially lipoidal membranes with equivalent permeabilities and no evident aqueous pore pathways.