Buccal Patches-A Review

Rajesh Kumar. D, Vinod Kumar. K, Sai Koteswar Sarma. D, Sathish Kumar. K, Shakir Ahmad. SK, Geethavani. M

Siddartha Institute of Pharmaceutical Sciences, Jonnalagadda, Narsaraopeyt, Guntur (Dt), Andhrapradesh

*Corresponding Author E-mail: rajeshpharma89@gmail.com

ABSTRACT:

Buccal delivery refers to the drug release which can occur when a dosage form is placed in the outer vestibule between the buccal mucosa and gingival. This route has various advantages includes bypass of first pass metabolism, better enzymatic flora for absorption and patient compliance. Buccal drug absorption occurs by passive diffusion of the nonionized species. Mucoadhesion may be affected by a number of factors, including hydrophilicity, molecular weight, cross-linking, swelling, pH, and the concentration of the active polymer. There are two types of buccal dosage form,they are matrix type and reservoir type. The basic components of buccal drug delivery system are drug substance, bio adhesive polymers, backing membrane permeation enhancers. There are two methods for preparation of buccal patches include solvent castng method and direct milling method. The evaluation tests include surface PH, thickness measurement, swelling study, thermal Analysis study, morphological characterizayion, water absorption capacity test, Ex-vivo bioadhesion test, in vitro drug release, permeation study, Ex-vivo mucoadhesion time and stability study in human saliva.

KEYWORDS: First pass metabolism, PH, matrix type, reservoir type and buccal patches.

INTRODUCTION:

BUCCAL DRUG DELIVERY SYSTEM:

A delivery system designed to deliver drugs systemically or locally via buccal mucosa. Buccal delivery refers to the drug release which can occur when a dosage form is placed in the outer vestibule between the buccal mucosa and gingival.

Among the various routes of drug delivery, oral route is perhaps the most preferred to the patient and the clinician alike. However peroral administration of drugs has advantages such as hepatic first pass metabolism and enzymatic degradation within GIT, that prohibit oral administration of certain classes of drugs especially proteins and peptides. Consequently other absorptive mucosas are considered as potential sites for drug administration.

Advantages of Buccal Patches:

1. The oral mucosa has a rich blood supply. Drugs are absorbed from the oral cavity through the oral mucosa, and transported through the deep lingual or facial vein, internal jugular vein and braciocephalic vein into the systemic circulation.

2. Buccal administration, the drug gains direct entry into the systemic circulation thereby bypassing the first pass effect. Contact with the digestive fluids of gastrointestinal tract is avoided which might be unsuitable for stability of many drugs like insulin or other proteins, peptides and steroids. In addition, the rate of drug absorption is not influenced by food or gastric emptying rate.

3. The area of buccal membrane is sufficiently large to allow a delivery system to be placed at different occasions, additionally; there are two areas of buccal membranes per mouth, which would allow buccal drug delivery systems to be placed, alternatively on the left and right buccal membranes.

4. Buccal patch has been well known for its good accessibility to the membranes that line the oral cavity, which makes application painless and with comfort.

5. Patients can control the period of administration or terminate delivery in case of emergencies. The buccal drug delivery systems easily administered into the buccal cavity. The novel buccal dosage forms exhibits better patient compliance[26].

Disadvantages of buccal patches:

1. Once placed at the absorption site and the dosage form should not be disturbed.

2. The drug swallowed in saliva is lost.

3. Properties like unpleasant taste or odour, irritability to the mucosa and stability at salivary pH posses limitations to the choice of drug.

4. Only drugs with small dose can be administered.

5. Eating and drinking may become restricted[1,2].

Structure of oral mucosa:

Oral mucosa consists of two layers, the surface stratified squamous epithelium and the deeper lamina propria. The epithelium consists of four layers for the keratinized oral mucosa and the nonkeratinized has the two of deeper four layers but does not have the two superficial final layer; it has a nonspecific superficial layer instead:

· Stratum basale (basal layer)

· Stratum spinosum (prickle layer)

· Stratum granulosum (granular layer)

· Stratum corneum (keratinized layer)

Depending on the region of the mouth, the epithelium may be nonkeratinized or keratinized. Nonkeratinized squamous epithelium covers the soft palate, inner lips, inner cheeks, and the floor of the mouth, and ventral surface of the tongue. Keratinized squamous epithelium is present in the attached gingiva and hard palate as well as areas of the dorsal surface of the tongue[12][13].

Keratinization is the differentiation of keratinocytes in the stratum granulosum into nonvital surface cells or squames to form the stratum corneum. The cells terminally differentiate as they migrate to the surface from the stratum basale where the progenitor cells are located to the superficial surface[27].

Unlike keratinized epithelium, nonkeratinized epithelium normally has no superficial layers showing keratinization. Nonkeratinized epithelium may, however, readily transform into a keratinizing type in response to frictional or chemical trauma, in which case it undergoes hyperkeratinization.This change to hyperkeratinization commonly occurs on the usually nonkeratinized buccal mucosa when the linea alba forms, a white ridge of calloused tissue that extends horizontally at the level where the maxillary and mandibular teeth come together and occlude. Histologically, an excess amount of keratin is noted on the surface of the tissue, and the tissue has all the layers of an orthokeratinized tissue with its granular and keratin layers. In patients who have habits such as clenching or grinding (bruxism) their teeth, a larger area of the buccal mucosa than just the linea alba becomes hyperkeratinized. This larger white, rough, raised lesion needs to be recorded so that changes may be made in the dental treatment plan regarding the patient’s parafunctional habits[13][14].

Even keratinized tissue can undergo further level of hyperkeratinization; an increase in the amount of keratin is produced as a result of chronic physical trauma to the region. Changes such as hyperkeratinization are reversible if the source of the injury is removed, but it takes time for the keratin to be shed or lost by the tissue. Thus, to check for malignant changes, a baseline biopsy and microscopic study of any whitened tissue may be indicated, especially if in a high-risk cancer category, such with a history of tobacco or alcohol use or are HPV positive. Hyperkeratinized tissue is also associated with the heat from smoking or hot fluids on the hard palate in the form of nicotinic stomatitis[12,15].

The lamina propria is a fibrous connective tissue layer that consists of a network of type I and III collagen and elastin fibers in some regions. The main cells of the lamina propria are the fibroblasts, which are responsible for the production of the fibers as well as the extracellular matrix.

The lamina propria, like all forms of connective tissue proper, has two layers: papillary and dense. The papillary layer is the more superficial layer of the lamina propria. It consists of loose connective tissue within the connective tissue papillae, along with blood vessels and nerve tissue. The tissue has an equal amount of fibers, cells, and intercellular substance. The dense layer is the deeper layer of the lamina propria. It consists of dense connective tissue with a large amount of fibers. Between the papillary layer and the deeper layers of the lamina propria is a capillary plexus, which provides nutrition for the all layers of the mucosa and sends capillaries into the connective tissue papillae[1].

A submucosa may or may not be present deep to the dense layer of the lamina propria, depending on the region of the oral cavity. If present, the submucosa usually contains loose connective tissue and may also contain adipose connective tissue or salivary glands, as well as overlying bone or muscle within the oral cavity[12].

A variable number of Fordyce spots or granules are scattered throughout the non keratinized tissue. These are a normal variant, visible as small, yellowish bumps on the surface of the mucosa. They correspond to deposits of sebum from misplaced sebaceous glands in the submucosa that are usually associated with hair follicles[12,27].

A basal lamina (basement membrane without aid of the microscope) is at the interface between the oral epithelium and lamina propria similar to the epidermis and dermis[26] .

1-Stratum basale (basal layer)

2-Stratum spinosum (prickle layer)

3-Stratum granulosum (granular layer)

4-Stratum corneum (keratinized layer)

MECHANISM OF BUCCAL ABSORPTION:

Buccal drug absorption occurs by passive diffusion of the nonionized species, a process governed primarily by a concentration gradient, through the intercellular spaces of the epithelium. The passive transport of non-ionic species across the lipid membrane of the buccal cavity is the primary transport mechanism. The buccal mucosa has been said to be a lipoidal barrier to the passage of drugs, as is the case with many other mucosal membrane and the more lipophilic the drug molecule, the more readily it is absorbed[3]. The dynamics of buccal absorption of drugs could be adequately described by first order rate process. Several potential barriers to buccal drug absorption have been identified. Dearden and Tomlison (1971) pointed out that salivary secretion alters the buccal absorption kinetics from drug solution by changing the concentration of drug in the mouth. The linear relationship between salivary secretion and time is given as follows

-dm = KC

dt ViVt

Where,

M –Mass of drug in mouth at time t

K - Proportionality constant

C - Concentration of drug in mouth at time

Vi - The volume of solution put into mouth cavity and

Vt - Salivary secretion rate

Factors Affecting Mucoadhesion:

Mucoadhesion may be affected by a number of factors, including hydrophilicity, molecular weight, cross-linking, swelling, pH, and the concentration of the active polymer[11,16,18].

Hydrophilicity:

Bioadhesive polymers possess numerous hydrophilic functional groups, such as hydroxyl and carboxyl. These groups allow hydrogen bonding with the substrate, swelling in aqueous media, thereby allowing maximal exposure of potential anchor sites. In addition, swollen polymers have the maximum distance between their chains leading to increased chain flexibility and efficient penetration of the substrate[12].

Molecular weight:

The interpenetration of polymer molecules is favored by low-molecular-weight polymers, whereas entanglements are favored at higher molecular weights. The optimum molecular weight for the maximum mucoadhesion depends on the type of polymer, with bioadhesive forces increasing with the molecular weight of the polymer up to 100,000. Beyond this level, there is no further gain[9,19].

Crosslinking and swelling:

Cross-link density is inversely proportional to the degree of swelling[7]. The lower the cross-link density, the higher the flexibility and hydration rate; the larger the surface area of the polymer, the better the mucoadhesion. To achieve a high degree of swelling, a lightly cross-linked polymer is favored. However, if too much moisture is present and the degree of swelling is too great, a slippy mucilage results and this can be easily removed from the substrate[8]. The mucoadhesion of cross-linked polymers can be enhanced by the inclusion in the formulation of adhesion promoters, such as free polymer chains and polymers grafted onto the preformed network [9,18].

Spatial confirmation:

Besides molecular weight or chain length, spatial conformation of a polymer is also important. Despite a high molecular weight of 19,500,000 for dextrans, they have adhesive strength similar to that of polyethylene glycol (PEG), with a molecular weight of 200,000. The helical conformation of dextran may shield many adhesively active groups, primarily responsible for adhesion, unlike PEG polymers, which have a linear conformation [12,16].

pH:

The pH at the bioadhesive to substrate interface can influence the adhesion of bioadhesives possessing ionizable groups. Many bioadhesives used in drug delivery are polyanions possessing carboxylic acid functionalities. If the local pH is above the pK of the polymer, it will be largely ionized; if the pH is below the pK of the polymer, it will be largely unionized. The approximate pKa for the poly(acrylic acid) family of polymers is between 4 and 5. The maximum adhesive strength of these polymers is observed around pH 4–5 and decreases gradually above a pH of 6. A systematic investigation of the mechanisms of mucoadhesion clearly showed that the protonated carboxyl groups, rather than the ionized carboxyl groups, react with mucin molecules, presumably by the simultaneous formation of numerous hydrogen bonds [20].

Concentration of active polymer:

Ahuja stated that there is an optimum concentration of polymer corresponding to the best mucoadhesion. In highly concentrated systems, beyond the optimum concentration the adhesive strength drops significantly[11]. In concentrated solutions, the coiled molecules become solvent-poor and the chains available for interpenetration are not numerous. This result seems to be of interest only for more or less liquid mucoadhesive formulations. It was shown by Duchêne that, for solid dosage forms such as tablets, the higher the polymer concentration, the stronger the mucoadhesion[17].

Drug excipient concentration:

Drug/excipient concentration may influence the mucoadhesion. Blanco Fuente studied the effect of propranolol hydrochloride to Carbopol® (a lightly cross-linked poly(acrylic acid) polymer) hydrogels adhesion[21]. Author demonstrated increased adhesion when water was limited in the system due to an increase in the elasticity, caused by the complex formation between drug and the polymer. While in the presence of large quantities of water, the complex precipitated out, leading to a slight decrease in the adhesive character. Increasing toluidine blue O (TBO) concentration in mucoadhesive patches based on Gantrez® (poly(methylvinylether/maleic acid) significantly increased mucoadhesion to porcine cheek tissue. This was attributed to increased internal cohesion within the patches due to electrostatic interactions between the cationic drug and anionic copolymer[21].

STRUCTURE AND DESIGN OF BUCCAL DOSAGE FORM:

Buccal Dosage form can be of following types

1.Matrix type:

The buccal patch designed in a matrix configuration contains drug, adhesive and additives mixed together. Tran mucosal drug delivery systems can be bidirectional or unidirectional.

2. Reservoir type:

The buccal patch designed in a reservoir system contains a cavity for the drug and additives separate from the adhesive. An impermeable backing is applied to control the direction of drug delivery; to reduce patch deformation and disintegration while in the mouth; and to prevent drug loss. Additionally, the patch can be constructed to undergo minimal degradation in the mouth, or can be designed to dissolve almost immediately[22].

3) patches release the drug only into the mucosa.

The basic components of buccal drug delivery system are

1) Drug substance

2) Bio adhesive polymers

3) Backing membrane

4) Permeation enhancers[4]

1. Drug substance:

Before formulating mucoadhesive drug delivery systems, one has to decide whether the intended, action is for rapid release/prolonged release and for local/systemic effect. The selection of suitable drug for the design of buccoadhesive drug delivery systems should be based on pharmacokinetic properties.

The drug should have following characteristics,

· The conventional single dose of the drug should be small.

· The drugs having biological half-life between 2-8 hrs are good candidates for controlled drug delivery.

· Tmax of the drug shows wider-fluctuations or higher values when given orally.

· Through oral route drug may exhibit first pass effect or presystemic drug elimination.

· The drug absorption should be passive when given orally[23].

2. Bioadhesive polymer:

The first step in the development of buccoadhesive dosage forms is the selection and Characterization of appropriate bio adhesive polymers in the formulation. Bio adhesive polymers play a major role in buccoadhesive drug delivery systems of drugs. Polymers are also used in matrix devices in which the drug is embedded in the polymer matrix, which control the duration of release of drugs[4]. Bio adhesive polymers are from the most diverse class and they have considerable benefits upon patient health care and treatment[22]. The drug is released into the mucous membrane by means of rate controlling layer or core layer. Bio adhesive polymers which adhere to the mucin/ epithelial surface are effective and lead to significant improvement in the oral drug delivery[24].

An ideal polymer for buccoadhesive drug delivery systems should have following Characteristics[23,28].

· It should be inert and compatible with the environment

· The polymer and its degradation products should be non-toxic absorbable from the mucous layer.

· It should adhere quickly to moist tissue surface and should possess some site specificity.

· The polymer must not decompose on storage or during the shelf life of the dosage form.

· The polymer should be easily available in the market and economical.

· It should allow easy incorporation of drug in to the formulation Criteria followed in polymer selection It should form a strong non covalent bond with the

· mucin/epithelial surface.

· It must have high molecular weight and narrow distribution.

· It should be compatible with the biological membrane.

Examples of good bioadhesive polymers include hydroxyl propyl cellulose (HPC), hydroxyl propyl methyl cellulose (HPMC), carbopol 934P, gelatin, pectin, PVP 44,000, sodium alginate, hydroxy ethyl cellulose, PEG 6000, tragacanth, Gantrez-AN, methyl cellulose, carboxy methyl cellulose sodium, carboxymethyl cellulose, Gantrez AN-139, chitosan and diethylamino ethyl dextrin.

Polymer controlling rate of drug release from buccal mucoadhesive patches:

The polymers which are insoluble in saliva or water can be used as efficient matrix systems through which rate of release of drug can be controlled as desired. Examples for this category include ethyl cellulose and butyl rubber.

Water-soluble polymers can be used for controlling rate of release in which, rate of polymer dissolution will be release rate determining step.

3. Backing membrane:

Backing membrane plays a major role in the attachment of bioadhesive devices to the mucus membrane. materials used as backing membrane should be inert, and impermeable to the drug and penetration enhancer. Such impermeable membrane on buccal bioadhesive patches prevents the drug loss and offers better patient compliance.

The commonly used materials in backing membrane include carbopol, magnesium stearate, HPMC, HPC, CMC, polycarbophil etc[23].

Polymers used to prepare backing membrane:

The polymer whose solution can be casted into thin pore less uniform water impermeable film can be used to prepare backing membrane of patches. It should have good flexibility and high tensile strength and low water permeation. They should be stable on long storage maintaining their initial physical properties. The cellulose acetate in concentration of 2.4% w/v in acetone with 10% of plasticizer (PEG 4000 or glycerol) of total polymer weight when air dried produces a thin film suitable for backing membrane purpose. Similarly, 2-4% w/v solution of ethyl cellulose in 1:4 mixture of alcohol: toluene and suitable plasticizer can be casted into film.

The backing membrane can be of two types

· A polymer solution casted into thin film. It is biodegradable in nature.

· A polyester laminated paper with polyethylene. It is not biodegradable.

The main function of backing membrane is to provide,

· Unidirectional drug flow to buccal mucosa.

· It prevents the drug to be dissolved in saliva and hence swallowed avoiding the contact between drug and saliva.

The material used for the backing membrane must be inert and impermeable to drugs and penetration enhancers. The thickness of the backing membrane must be thin and should be around 75-100 microns.

The most commonly used backing materials are polyester laminated paper with polyethylene. Other examples include cellophane-325, multiphor sheet and polyglassine paper.

4. Permeation enhancers:

Substances that facilitate the permeation through buccal mucosa are referred as permeation enhancers. Selection of enhancer and its efficacy depends on the physicochemical properties of the drug, site of administration, nature of the vehicle and other excipients.

Mechanisms of action of permeation:

1. Changing mucus rheology:

By reducing the viscosity of the mucus and saliva overcomes this barrier.

2. Increasing the fluidity of lipid bilayer membrane:

Disturb the intracellular lipid packing by interaction with either lipid packing by interaction with either lipid or protein components.

3. Acting on the components at tight junctions:

By inhibiting the various peptidases and proteases present within buccal mucosa, thereby overcoming the enzymatic barrier. In addition, changes in membrane fluidity also alter the enzymatic activity indirectly.

4. Increasing the thermodynamic activity of drugs:

Some enhancers increase the solubility of drug there by alters the partition coefficient.

Categories and examples of membrane permeation enhancers[25]

1. Bile salts and other steroidal detergents:

Sodium glycocholate, sodium taurocholate, sodium taurodihydro fusidate, and sodium glycol dihydro fusidate.

2. Surfactants:

i) Non ionic: Laureth-a, polysorbate-9, sucrose esters and do-decyl maltoside.

ii) Cationic: Cetyl trimethyl ammonium bromide

iii) Anionic: Sodium lauryl sulphate.

3. Fatty acids: Oleic acid, lauric acid, caproic acid

4. Other enhancers:

i) Azones

ii) Salicylates

iii) Chelating agents

iv) Sulfoxides e.g. Dimethyl sulfoxide (DMSO)

Preparation methods:

1.Solvent casting:

In solvent casting and particulate leaching (SCPL), a polymer is dissolved in an organic solvent. Particles, mainly salts, with specific dimensions are then added to the solution. The mixture is shaped into its final geometry. For example, it can be cast onto a glass plate to produce a membrane or in a three-dimensional mold to produce a scaffold. When the solvent evaporates it creates a structure of composite material consisting of the particles together with the polymer. The composite material is then placed in a bath which dissolves the particles, leaving behind a porous structure[5].

2.Direct milling:

In this, patches are manufactured without the use of solvents (solvent-free). Drug and excipients are mechanically mixed by direct milling or by kneading, usually without the presence of any liquids. After the mixing process, the resultant material is rolled on a release liner until the desired thickness is achieved. The backing material is then laminated as previously described[6].

Evaluation tests:

1. Surface pH:

Buccal patches are left to swell for 2 hr on the surface of an agar plate. The surface pH is measured by means of a pH paper placed on the surface of the swollen patch

2. Thickness measurements:

The thickness of each film is measured at five different locations (centre and four corners) using an electronic digital micrometer.

3. Swelling study:

Buccal patches are weighed individually (designated as W1), and placed separately in 2% agar gel plates, incubated at 37°C ± 1°C, and examined for any physical changes. At regular 1-hour time intervals until 3 hours, patches are removed from the gel plates and excess surface water is removed carefully using the filter paper. The swollen patches are then reweighed (W2) and the swelling index (SI) is calculated using the following formula.

4. Thermal analysis study:

Thermal analysis study is performed using differential scanning calorimeter (DSC).

5. Morphological characterization:

Morphological characters are studied by using scanning electron microscope (SEM).

6. Water absorption capacity test:

Circular Patches, with a surface area of 2.3 cm2 are allowed to swell on the surface of agar plates prepared in simulated saliva (2.38 g Na2HPO4, 0.19 gKH2PO4, and 8 g NaCl per litter of distilled water adjusted with phosphoric acid to pH 6.7), and kept in an incubator maintained at 37°C ± 0.5°C. At various time intervals (0.25, 0.5, 1, 2, 3, and 4 hours), samples are weighed (wet weight) and then left to dry for 7 days in a desiccator over anhydrous calcium chloride at room temperature then the final constant weights are recorded. [26]

7. Ex-vivo bioadhesion test:

The fresh sheep mouth separated and washed with phosphate buffer (pH 6.8). A piece of gingival mucosa is tied in the open mouth of a glass vial, filled with phosphate buffer (pH 6.8). This glass vial is tightly fitted into a glass beaker filled with phosphate buffer (pH 6.8, 37°C ± 1°C) so it just touched the mucosal surface. The patch is stuck to the lower side of a rubber stopper with cyano acrylate adhesive. Two pans of the balance are balanced with a 5-g weight. The 5-g weight is removed from the left hand side pan, which loaded the pan attached with the patch over the mucosa. The balance is kept in this position for 5 minutes of contact time. The water is added slowly at 100 drops/min to the right-hand side pan until the patch detached from the mucosal surface. The weight, in grams, required to detach the patch from the mucosal surface provided the measure of mucoadhesive strength.

8. In vitro drug release:

The United States Pharmacopeia (USP) XXIII-B rotating paddle method is used to study the drug release from the bilayered and multilayered patches. The dissolution medium consisted of phosphate buffer pH 6.8. The release is performed at 37°C ± 0.5°C, with a rotation speed of 50 rpm. The backing layer of buccal patch is attached to the glass disk with instant adhesive material. The disk is allocated to the bottom of the dissolution vessel. Samples (5 ml) are withdrawn at predetermined time intervals and replaced with fresh medium. The samples filtered through whatman filter paperand analyzed for drug content after appropriate dilution. The in- vitro buccal permeation through the buccal mucosa (sheep and rabbit) is performed using Keshary-Chien/Franz type glass diffusion cell at 37°C± 0.2°C. Fresh buccal mucosa is mounted between the donor and receptor compartments. The buccal patch is placed with the core facing the mucosa and the compartments clamped together. The donor compartment is filled with buffer.

9. Permeation study of buccal patch:

The receptor compartment is filled with phosphate buffer pH 6.8, and the hydrodynamics in the receptor compartment is maintained by stirring with a magnetic bead at 50 rpm. Samples are withdrawn at predetermined time intervals and analyzed for drug content.

10. Ex-vivo mucoadhesion time:

The ex-vivo mucoadhesion time performed after application of the buccal patch on freshly cut buccal mucosa (sheep and rabbit). The fresh buccal mucosa is tied on the glass slide, and a mucoadhesive patch is wetted with 1 drop of phosphate buffer pH 6.8 and pasted to the buccal mucosa by applying a light force with a fingertip for 30 seconds. The glass slide is then put in the beaker, which is filled with 200 ml of the phosphate buffer pH 6.8, is kept at 37°C ± 1°C. After 2 minutes, a 50-rpm stirring rate is applied to simulate the buccal cavity environment, and patch adhesion is monitored for 12 hours. The time for changes in colour, shape, collapsing of the patch, and drug content is noted.

11. Stability study in human saliva:

The stability study of optimized bilayered and multilayered patches is performed in human saliva. The human saliva is collected from humans (age 18-50years). Buccal patches are placed in separate petri dishes containing 5ml of human saliva and placed in a temperature-controlled oven at 37°C ± 0.2°C for 6 hours. At regular time intervals (0, 1, 2, 3, and 6 hours), the dose formulations with better bioavailability are needed. Improved methods of drug release through transmucosal and transdermal methods would be of great significance, as by such routes, the pain factor associated with parenteral routes of drug administration can be totally eliminated. Buccal adhesive systems offer innumerable advantages in terms of accessibility, administration and withdrawal, retentively, low enzymatic activity, economy and high patient compliance. Adhesion of buccal adhesive drug delivery devices to mucosal membranes leads to an increased drug concentration gradient at the absorption site and therefore improved bioavailability of systemically delivered drugs. In addition, buccal adhesive dosage forms have been used to target local disorders at the mucosal surface (e.g., mouth ulcers) to reduce the overall dose required and minimize side effects that may be due to systemic administration of drugs. Researchers are now looking beyond traditional polymer networks to find other innovative drug transport systems. Currently solid dosage forms, liquids and gels applied to oral cavity are commercially successful. The future direction of buccal adhesive drug delivery lies in vaccine formulations and delivery of small proteins/peptides. [26]

CONCLUSION:

Due to various advantages of buccal patches, these are using extensively in now-a-days.

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Received on 12.04.2014 Modified on 20.05.2014

Res. J. Pharm. Dosage Form. and Tech. 6(3):July- Sept. 2014; Page 167-173