Over the decades, peroral delivery has been the popular route of administration for the majority of therapeutic agents targeting systemic delivery. Oral administration generally leads to extensive presystemic elimination, which may include GI degradation, metabolism, or first-pass clearance via the liver. Transmucosal drug delivery offers attractive alternative routes for administration of drugs and may avoid the significant drawbacks of peroral and parenteral administration. These routes of administration bypass first pass metabolism by delivering drug directly into the systemic circulation. Buccal drug delivery offers several advantages over the oral route and other alternative routes of drug administration. The membranes that line the oral cavity are readily accessible, robust, and exhibit fast cellular recovery following local stress or damage and are exposed to various exogenous compounds. Properly constructed oral transmucosal drug delivery systems are easy and painless to administer and well accepted by the patient. Precise localization of the dosage form is possible and there is the ability to terminate delivery when required (e.g. because of toxicity).