A composite formulation has been developed for selective, high
efficacy delivery to specific regions of the mouth and
gastrointestinal tract. The formulation is typically in the form of a tablet or
capsule, which may include microparticles or beads. The formulation uses
bioadhesive and
controlled release elements to direct release to specific regions, where the
drug is absorbed in enhanced amounts relative to the formulation in the absence of the
bioadhesive and / or
controlled release elements. This is demonstrated by an example showing delivery of
gabapentin with a greater
area under the curve (“AUC”) relative to the FDA reference
immediate release drug, i.e., the AUC of the composite
bioadhesive formulation is greater than 100% of the AUC of the
immediate release drug. In the preferred embodiments, the formulation includes drug to be delivered,
controlled release elements, and one or more bioadhesive elements. The bioadhesive
polymer may be either dispersed in the matrix of the tablet or applied as a direct compressed
coating to the
solid oral
dosage form. The controlled release elements are selected to determine the site of release. The bioadhesive components are selected to provide retention of the formulation at the desired site of uptake and administration. By selecting for both release and retention at a specific site, typically based on time of transit through the
gastrointestinal tract, one obtains enhanced
efficacy of uptake of the drug. This is particularly useful for drugs with narrow windows of absorption, and drugs with poor
solubility such as the BCE
class III and class IV drugs.