Buccal delivery devices

FIG. 7. Schematic diagram showing the geometric designs of buccal delivery devices (from Ref 97). 

The buccal permeability of the non-steroidal antiinflammatory drug, diclofenac sodium, has been evaluated in a dog model. The dog was selected because of the similarity of its buccal mucosa to that of man. Analysis of the buccal data indicated that diclofenac sodium permeability followed an essentially zero-order kinetic process with a minimal lag phase. Permeability of the drug was estimated to be 3 mg/cm2.h but significant differences were observed between animals. The absorption rate with the transbuccal delivery device decreased with time whereas the corresponding rate with a saturated solution was constant. This difference was attributed to the time dependency of drug delivery from the device and was modeled on the basis of release from a membrane-dispersed monolith combined with constant buccal permeability. The predictions of the model showed excellent agreement with the experimental data. 

The above procedure was also employed to investigate buccal absorption from the HEMAC experimental delivery device. As in the case of the diffusion cell the drug-loaded disc was positioned on the inner central surface of the buccal mucosa. An impermeable film coated with mucosal adhesive (F-4000, Adhesives Research, Glen Rock, PA) on the periphery was then positioned over the HEMAC disc to prevent dehydration and to secure the device in place on the mucosal surface. The disc was allowed to remain in contact with the mucosa for 4 h before it was removed for quantitation of residual drug content. Blood samples were collected over the same interval as for the saturated solution and processed in the same manner. 

Figure 3. In vitro delivery of diclofenac sodium from a buccal drug delivery device (details of the dissolution method are given in the text). ...

Figure 6. Plasma concentrations of diclofenac sodium after application of a buccal drug delivery device to the mucosa of 4 Beagle dogs.

Figure 7. Loo-Riegelman plots for the saturated solution and buccal drug delivery device.

The literature cites numerous studies on buccal absorption in animals and man. However, in most studies experimental conditions were not well defined, making it difficult to draw appropriate conclusions from the experimental data. In the studies reported here the area of buccal mucosa exposed to the drug was carefully controlled, as was the rate of drug delivery in the case of the buccal disc device. The disposition kinetics of the drug was also defined from intravenous data to allow both the rate and extent of absorption to be determined. 

Buccal mucosa histology, 311-315 Burst period, frustum array drug delivery device, 332... 

The term mucoadhesion is commonly used to describe an interaction between the mucin layer, which lines the entire GI tract, and a bioadhesive polymer, which could be natural or synthetic in origin.From the oral delivery standpoint, these systems are used to immobilize and localize a drug delivery device in the selected regions of the GI tract, which could be an oral cavity (buccal and sublingual routes), the esophagus, stomach, small intestine, or colon (oral route). For the most part, research in this area has focused on the design of polymeric micro- and nanoparticulate systems that use hydrophilic polymers, primarily due to their propensity to interact with the mucosal surface. ... 

The size of the delivery system varies with the type of formulation, i.e., a buccal tablet may be approximately 5-8 mm in diameter, whereas a flexible buccal patch may be as large as 10-15 cm in area. Mucoadhesive buccal patches with a surface area of 1-3 cm are most acceptable. It has been estimated that the total amount of drug that can be delivered across the buccal mucosa from a 2-cm system in 1 day is approximately 10-20 mg.f The shape of the delivery system may also vary, although for buccal drug administration, an ellipsoid shape appears to be most acceptable. The thickness of the delivery device is usually restricted to only a few millimeters. The location of the delivery device also needs to be considered. A mucoadhesive retentive system is preferred over a conventional dosage form. A bioadhesive buccal patch would appear to be the most appropriate delivery system because of its flexibility and the area of the buccal mucosa available for its application. The maximal duration of buccal drug retention and absorption is approximately 4-6 h because food and/or liquid intake may require removal of the delivery device. 

Remunan-Lopez, C., Portero, A., VilaJato, J.L., and Alonso, M.J., Design and evaluation of chitosan/ethylcellulose mucoadhesive bilayered devices for buccal drug delivery, J. Control. Rel., 55 143-152 (1998). 

Products with readily variable dose levels are required. Methods for depositing drugs in solution onto biosoluble and biodegradable matrices also offer the possibility of ready and accurate fabrication in hospital and community pharmacies. A matrix platform for such products is required. Developments in bubble jet devices (22) suggest the possibility of the deposition and the adsorption of the smallest doses onto and into suitable matrices for delivery, say, to neonates by oral or buccal routes. 

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