Mucoadhesive Buccal Drug Delivery Systems: An Updated Review

Mucoadhesive buccal drug delivery systems are gaining popularity as an alternative to conventional oral dosage forms because of their ability to increase drug bioavailability, sustain drug release, and enhance patient compliance. These systems stick to the buccal mucosa for direct absorption of the drug into systemic circulation; hence avoiding first-pass hepatic metabolism and degradation in the gastrointestinal tract. This makes them very attractive for use with drugs that have poor bioavailability through the mouth, or have short biological half-lives. This review presents an updated overview of recent advances in mucoadhesive buccal drug delivery, with emphasis on formulation strategies, polymer selection, and the mechanisms of mucoadhesion. Commonly used polymers such as chitosan, Carbopol, hydroxypropyl methylcellulose, and sodium alginate are discussed in terms of their mucoadhesive properties, biocompatibility, and ability to control drug release. The major theories of mucoadhesion are wetting theory, diffusion theory, and electronic theory which will be described briefly here since these theories explain polymer-mucosal interactions. This review also discusses key factors that affect drug permeation across buccal mucosa by highlighting physiological barriers like limited surface area available for absorption due to small size of mouth cavity compared to other routes of administration plus salivary flow dilution effect and rapid turnover rate of mucosa. The challenges faced by formulations such as irritation on the mucosa variability in residence time stability of drugs are also discussed. Emerging technologies along with future research directions supporting safe effective non-invasive development are highlighted