The buccal mucosa is an alternative route for oral administration of drugs that show a strong first passage hepatic metabolism and high sensitivity to acidic environment in stomach, allowing improvement of its bioavailability. Nevertheless, administration of drugs in the buccal mucosa is limited due to its low permeability. Unlike that of the small intestine, the mucosa of the oral cavity has a stratified squamous epithelium with 20 to 40 layers of cells that act as a barrier against endogenous alterations and exogenous substances that reach the oral cavity. In addition, for an effective administration of drugs in the oral mucosa, it is necessary to increase the time of contact between the oral mucosa and the administered pharmaceutical form. From these characteristics, the objectives of this study are to increase the model drug (omeprazole) stability and solubility in the oral cavity environment (saliva), and simultaneously to use strategies to increase the drug absorption through the buccal mucosa.