1. INTRODUCTION
The oral cavity is an attractive site online for drug delivery due to ease of management, avoidance of feasible drug degradation inside the gastrointestinal tract, and first-skip metabolism. inside the oral mucosal hollow space, transport of medication is classified into 3 classes: (i) sublingual delivery, that is systemic transport of drugs thru the mucosal membranes lining the floor of the mouth (ii) buccal delivery, that is drug administration via the mucosal membranes lining the cheeks (buccal mucosa), and (iii) local delivery, which is drug delivery into the oral cavity.
The buccal area of the oral cavity is an attractive goal for management of the drug of desire. Buccal delivery includes the administration of the preferred drug through the buccal mucosal membrane lining of the oral hollow space. in contrast to oral drug delivery, which offers a antagonistic surroundings for pills, specially proteins and polypeptides, because of acid hydrolysis and the hepatic first-bypass effect, the mucosal lining of buccal tissues gives a far milder surroundings for drug absorption. other routes, which include nasal, ocular, pulmonary, rectal, and vaginal drug management, have furnished excellent possibilities for the transport of a diffusion of compounds. however, the mucosal lining of the oral cavity gives a few distinct advantages.
‘ It is richly vascularized and more accessible for the administration and removal of a dosage form.
‘ Additionally, buccal drug delivery has a high patient acceptability compared to other non-oral routes of drug administration.
‘ Harsh environmental factors that exist in oral delivery of a drug are circumvented by buccal delivery. Avoiding acid hydrolysis in the gastrointestinal (GI) tract and bypassing the first-pass effect aresome of the advantages of this route of drug delivery.
The disadvantages associated with this route of drug delivery are:
‘ The low permeability of the buccal membrane specifically when compared to the sublingual membrane and a smaller surface territory. The aggregate surface territory of the films of the oral hole accessible for medication absorption is 170 cm2 of which ~50 cm2 speaks to non-keratinized tissues, including the buccal layer
‘ The continuous secretion of saliva (0.5’2 L/day) leads to subsequentdilution of the drug .
Gulping of saliva can likewise conceivably prompt the loss of broke up or suspended medication and, at last, the automatic evacuation of the dosage form.
These are some of the problems that are connected with buccal medication conveyance. In addition, the danger of stifling by automatically gulping the conveyance framework is a concern,in addition to the inconvenience of such a dosage form. at the point when the patient is eating or drinking. In any case, the favorable circumstances and late advance in conveying an assortment of mixes, particularly peptides and proteins, render the drawbacks of this course less critical . Fortunately, the enzyme activity in the buccal mucosa is relatively low compared toother mucosal routes(5)
1.1 Buccal mucosal structure and its suitability
Buccal area is that part of the mouth bounded anteriorly and laterally by way of the lips and the cheeks, posteriorly and medially by using the teeth and/or gums, and above and under by using the reflections of the mucosa from the lips and cheeks to the gums. numerous racemose, mucous, or serous glands are gift in the submucous tissue of the cheeks. The buccal glands are located among the mucous membrane and buccinator muscle: they are similar in shape to the labial glands, however smaller. about five, of a bigger size than the relaxation, are positioned among the masseter and buccinator muscle groups across the distal extremity of the parotid duct; their ducts open in the mouth opposite the pre molar enamel.They are called molar glands. Maxillary artery supplies blood to buccal mucosa and blood flow is faster and richer (2.4mL/min/cm2) than that in the sublingual, gingival and palatal regions thus facilitate passive diffusion of drug molecules across the mucosa. Thickness and blood flow characteristics of various regions are given in Table 1 .The thickness of the buccal mucosa is measured to be 500’800 ”m and is rough textured, hence suitable for retentive delivery systems. The turnover time for the buccal epithelium has been estimated at 5’6 days .Buccal mucosa composed of several layers of different cells as shown in Figure 1. The epithelium is similar to stratified squamous epithelia found in rest of the body and is about 40’50 cell layers thick(5).
Figure 1. Cross-section of buccal mucosa.
Lining epithelium of buccal mucosa is the non-keratinized stratified squamous epithelium that has thickness of approximately 500’600 ” and surface area of 50.2 cm2. Basement membrane, lamina propria followed by the submucosa is present below the epithelial layer .Lamina propria is rich with blood vessels and capillaries that open to the internal jugular vein. Lipid analysis of buccal tissues shows the presence of phospholipid 76.3%, glucosphingolipid 23.0% and ceramide NS at 0.72%. Other lipids such as acyl glucosylatedceramide and ceramides like Cer AH, CerAP, Cer NH, CerAS, and EOHP/NP are completely absent (Fox et al., 1998). The primary function of (buccal epithelium is the protection of the underlying tissue.
In non-keratinized areas, lipid-based permeability barriers in the external epithelial layers ensure the hidden tissue. In non-keratinized locales, lipid based penetrability obstructions in the external epithelial layers ensure the fundamental tissues against liquid loss)and entry of potentially harmful environmental agents such as antigens, carcinogens, microbial toxins and enzymes from foods and beverages.(7)