Article Type : Research Article
Authors : Mubarak ZO and Hameed F
Keywords : Buccal drug delivery system; BDDS, NDDS; Transmucosal drug delivery
Since the medication does not pass through the digestive system and therefore avoids the first-pass metabolism, buccal administration can provide better bioavailability and a faster onset of action for certain drugs as compared to oral administration. Buccal administration is a topical route of administration in which medications applied or retained in the buccal region (in the cheek) diffuse through the oral mucosa (tissues that line the mouth) and reach the bloodstream directly. Since the medication does not pass through the digestive system and therefore avoids the first-pass metabolism, buccal administration can provide better bioavailability and a faster onset of action for certain drugs as compared to oral administration. The present review presents various advantages, disadvantages, optimization, criteria for drug selection. The anatomy and physiology of buccal, dosage forms, factors affecting the absorption of drug from buccal cavity, absorption barriers, applications absorption enhancers and evaluation. This review also presents polymers in the buccal route of drug delivery.
The buccal formulation is used to treat both local and systemic issues in the mouth, specifically between the upper gums and the cheek. Buccal mucosa lines the inner cheek and is used to treat local and systemic conditions in the mouth between the upper gums and cheek. Buccal drug delivery has higher patient acceptability than other non-oral routes of drug administration because it is more vascularized and easier to administer and remove dosage. In the harsh gastrointestinal environment, using the buccal route would result in extensive first-pass metabolism and drug degradation [1,2]. Passive diffusion into the lipoidal membrane is the primary mode of drug absorption through the buccal mucosa. After absorption, the drug is transported to the jugular vein, which then drains into the circulation, bypassing the liver and avoiding first-pass metabolism. Large, hydrophilic, and unstable proteins, oligonucleotides, and polysaccharides, as well as conventional small drug molecules, can be delivered via the buccal route. Buccal drug delivery is the administration of medication through the buccal mucosa of the oral cavity. The medication is placed between the gums and the cheek during buccal administration. Medications in the form of pills, films, or sprays are available, 1-3 cm2 in size. It is recommended that you take 25 mg or less per day. Buccal delivery distribution takes 4-6 hours at the most [3,4] (Figure 1-3).
Figure 1: The buccal area is the inner lining of the cheek and lip, representing about one third of the surface area of the oral cavity.
Figure 2: Anatomy of oral cavity.
Figure 3: Drug transport across the mucosa can be transcellular or paracellular.
Ideal Characteristics of Buccal Adhesive Drug Delivery System
Uses of Buccal Delivery
Anatomy of Oral Mucosa
A layered squamous epithelium and a thicker lamina propria make up the oral mucosa. The stratum basale (base layer), stratum spinosum (prickle layer), stratum granulosum (granular layer), and stratum corneum (corneum layer) are the four layers that make up the epithelium of keratinized oral mucosa (keratinized layer). The two deep layers (basale and spinosum) remain the same in the nonkeratinized epithelium, but the outer layers are referred to as the intermediate and superficial layers. Depending on the area, the mouth epithelium may be nonkeratinized or keratinized. Nonkeratinized squamous epithelium covers the soft palate, inner lips, inner cheeks, the floor of the mouth, and the ventral surface of the tongue (Figure 2). Keratinized squamous epithelium can be found on the gingiva and hard palate, as well as parts of the tongue's dorsal surface [4,5]. Keratinocytes in the stratum granulosum divide into nonvital surface cells or squamous cells, resulting in the stratum corneum. As they move from the stratum basale, where progenitor cells are found, to the superficial surface, the cells terminally differentiate. Nonkeratinized epithelium, unlike keratinized epithelium, does not have keratinized superficial layers. In response to frictional or chemical trauma, the nonkeratinized epithelium can easily transform into keratinizing epithelium, resulting in hyperkeratinization. When the linea Alba appears, a white ridge of calloused tissue that extends horizontally at the stage where the maxillary and mandibular teeth come together and occlude, the buccal becomes hyperkeratinized. The tissue has all of the layers of orthokeratinized tissue, including the granular and keratin layers, and there is an abundance of keratin on the tissue's surface. Patients who clench or grit their teeth (bruxism) have a wider region of the buccal mucosa that becomes hyper keratinized than just the linea alba. This larger white, rough, raised lesion should be documented to account for the patient's parafunctional behavior in the dental care plan [6,7] (Figure 4).
Functions of Oral Mucosa
Actions like eating, drinking, and talking constantly put mechanical stress on the oral environment. Since the mouth is subjected to rapid changes in temperature and pH, it must be able to adapt rapidly. The only part of the body where taste can be detected in the mouth. The oral mucosa must perform a variety of functions as a result of its particular physiological characteristics. Protecting the underlying tissues from mechanical pressures, bacteria, and toxins in the mouth is one of the most essential functions of the oral mucosa. The hard palate and gingivae are closely bound by keratinized masticatory mucosa. It makes up one-quarter of all oral mucosa. It protects the underlying tissues by withstanding the loading forces of mastication. When chewing and talking, the mucosa covering the cheeks, lips, and mouth floor shifts to make room. It allows food to quickly move through the mouth during mastication while shielding the underlying tissues from trauma. It accounts for 60% of the oral mucosa [8,9]. Saliva is the most important secretion of the oral mucosa. Lubrication, pH buffering, and immunity are only a few of their functions. Saliva's lubricating and antimicrobial functions are primarily preserved by resting; saliva produces a flushing effect and aids in the removal of oral debris and noxious Saliva contains a variety of antimicrobial proteins that aid in the protection of the oral ecosystem against infectious agents. Salivary lysozyme, lactoferrin, salivary peroxidase, myeloperoxidase, and thiocyanate concentrations function as a defense mechanism. Three pairs of major salivary glands (parotid, submandibular, and sublingual) and several minor salivary glands produce saliva. It also helps in chemical digestion because it includes the enzyme amylase, which breaks down carbohydrates into sugars [9,10]. Sensation - The oral mucosa is highly sensitive to pain, touch, temperature, and taste because it is densely innervated. The trigeminal (V), facial (VII), glossopharyngeal (IX), and Vagus nerves are among the cranial nerves involved in mouth sensations (X). Specialized mucosa surrounds the dorsum of the tongue. It makes up about 15% of your oral mucosa and is made up of taste buds that allow you to taste stuff . Swallowing, gagging, and hunger are all mouth-related reflexes. While not as important in humans, some animals, such as dogs, rely on panting to control their temperature because sweat glands are only found in their paws [9,11].
Environment of Buccal Mucosa
The oral cavity is distinguished by the presence of saliva, which is an intercellular ground fluid that covers the cells of the oral epithelia and is supplied by the salivary glands. The primary and minor salivary glands secrete mucus, which is contained in saliva .