Roles of Lipids in the Permeability Barriers of Skin and Oral Mucosa

PubMed searches reveal much literature regarding lipids in barrier function of skin and less literature on lipids in barrier function of the oral mucosa. In terrestrial mammals, birds, and reptiles, the skin’s permeability barrier is provided by ceramides, fatty acids, and cholesterol in the outermost layers of the epidermis, the stratum corneum. This layer consists of about 10–20 layers of cornified cells embedded in a lipid matrix. It effectively prevents loss of water and electrolytes from the underlying tissue, and it limits the penetration of potentially harmful substances from the environment. In the oral cavity, the regions of the gingiva and hard palate are covered by keratinized epithelia that much resemble the epidermis. The oral stratum corneum contains a lipid mixture similar to that in the epidermal stratum corneum but in lower amounts and is accordingly more permeable. The superficial regions of the nonkeratinized oral epithelia also provide a permeability barrier. These epithelial regions do contain ceramides, cholesterol, and free fatty acids, which may underlie barrier function. The oral epithelial permeability barriers primarily protect the underlying tissue by preventing the penetration of potentially toxic substances, including microbial products. Transdermal drug delivery, buccal absorption, and lipid-related disease are discussed.

A REVIEW ON BUCCAL FILM: AN INOVATIVE DOSAGE FORM

Buccal administration of drugs leads to systemic circulation through internal jugular vein, bypassing them from hepatic first pass metabolism and leading to greater bioavailability. Buccal mucosa is most preferred site for both local as well as systemic action. For administration of drug through mucosal route, various types of dosage forms can be prepared. Buccal films can release topical drugs with controlled and sustained effects. Buccal films have the advantage of improved patient compliance because of reduced size with a suitable thickness as compare to other delivery systems. Buccal film can enhance absorption of active medicament as compared to others. Synthetic natural and semi synthetic polymers in low concentration can be used for the preparation of buccal films. Such types of dosage forms are cost effective, non-irritating, easy to handle, elegant, rapidly absorbable and most preferred by consumer. The review describes the anatomy of oral mucosa, mechanism of buccal absorption, methods to increase drug delivery via a buccal route, formulation aspects and evaluation parameters of buccal films.