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Abstract The present thesis focused on drug delivery via the buccal route, as a potential route for systemic delivery of water soluble vitamins. Pyridoxine hydrochloride (VB6) was selected in this thesis as a model water soluble vitamin. A considerable volume of research has been devoted, in the past decades, to the buccal route for systemic delivery of various drugs and dietary supplements including vitamins. The buccal route has attracted considerable attention as an alternative route for systemic drug delivery to overcome the limitations of conventional drug delivery routes. Invasive parenteral administration and poor bioavailability, drug degradation or intensive metabolism through oral route all can be avoided by buccal drug administration. Additionally, ease of drug administration, excellent accessibility, higher patient compliance, versatility in formulation design to accommodate different purposes, suitability for rapid onset of action in emergency due to rich vascularization of buccal mucosa, possibility for sustained drug release and permeability exceeding skin by 4000 times can be achieved through buccal drug delivery. The buccal mucosa is 500 – 600 μm and consists of stratified multilayered squamous epithelium separated from the underlying connective tissue by continuous undulating basement membrane. The upper one-third to one-quarter of the buccal epithelium generally forms the rate limiting barrier of the buccal mucosa. Drugs passively traverse the buccal mucosa by paracellular and/or transcellular route depending on their physicochemical properties. However, the rapid elimination of drugs due to the flushing action of saliva or the ingestion of foods stuffs and lack of dosage form retention at the site of absorption may lead to the requirement for frequent dosing and interruption of drug delivery. Thus, mucoadhesive dosage forms have been developed to localize the drug at absorption site and extend the contact time with buccal tissue. Various mucoadhesive buccal dosage forms have been introduced including adhesive tablets, gels, ointments, patches and more recently films. Liposomes are self-assembling sphere-shaped vesicles consisting of one or more phospholipid bilayers surrounding aqueous units with sizes ranging from a few nanometers to several micrometers. Liposomes have versatile applications in pharmaceutical drug delivery, biotechnology, cosmetology, food and farming industries. Liposomes are non toxic, flexible, biocompatible, completely biodegradable, and non immunogenic drug carriers. They offer many advantages such as suitability for sustained release systemic and non-systemic administration, improved solubility of drugs, improved transfer of hydrophilic and charged molecules, improved penetration into tissues, passive and active targeting, increased efficacy and therapeutic index of drug, increased drug stability, reduced side effects and toxicity of the encapsulated agent. |