BREAKING BARRIERS: ENHANCING DRUG ABSORPTION THROUGH BUCCAL MUCOSA

Buccal drug delivery has emerged as a compelling alternative to conventional administration routes due to the buccal mucosa’s favourable anatomical and physiological characteristics. Its rich vascularization, non-keratinized epithelium, and mucoadhesive potential collectively enable efficient systemic and localized drug delivery. These features facilitate rapid absorption of therapeutic agents while bypassing first-pass hepatic metabolism, thus significantly enhancing bioavailability and therapeutic efficacy. The advantages of buccal drug absorption are manifold. The route allows for rapid onset of action, patient-friendly administration, and improved compliance through self-administration. Additionally, the use of mucoadhesive systems such as patches, films, and tablets improves retention time at the absorption site and enhances localized effects. However, despite its benefits, buccal drug delivery faces several limitations. Challenges include limited permeability for macromolecules, potential washout by saliva, variability in dose due to formulation inconsistencies, and patient discomfort with prolonged dosage form retention. These issues necessitate the use of innovative strategies to overcome physiological and formulation-based barriers. This review explores the structural advantages of the buccal mucosa, including its robust connective tissue, regenerative capabilities, and permeability, making it an attractive site for the administration of both hydrophilic and lipophilic drugs. Various permeation enhancers have been employed to increase drug absorption including chemical agents such as surfactants, fatty acids, bile salts, and cyclodextrins, which modify mucosal barrier properties to facilitate drug penetration. Natural compounds like terpenes and essential oils offer biocompatible enhancement, while physical methods such as microneedles, iontophoresis, and electroporation create microchannels or use electrical currents to promote deeper drug permeation. These strategies not only improve drug flux but also expand the range of drugs that can be effectively delivered via the buccal route. The development of novel drug delivery systems is a cornerstone in optimizing buccal drug absorption. Buccal films, mucoadhesive patches, and in situ gels allow for controlled, sustained release and improved therapeutic outcomes. Advances in nanotechnology have led to the design of solid lipid nanoparticles, nanosuspensions, and liposomal formulations that enhance solubility and protect drugs from enzymatic degradation. Lipid-based and solid dispersion technologies also enhance the bioavailability of poorly water-soluble drugs. Bioadhesive polymers like chitosan and HPMC have been instrumental in increasing mucosal contact time and drug permeability. Hence, the review aims to focus on the current research and technological innovations which would continue to refine these systems, paving theway for broader clinical applications and more effective drug therapies.