The BIOROD system (see Figure 13) comprises a longitudinally compressed capsule shape and inner drug core encased in an impermeable
bioadhesive cylinder. One of the significant advantages of this system is its flexibility in constructing various designs
to allow release kinetics to meet therapeutic goals. Figure 14 shows two pulse-release behaviors of gabapentin from a BIOROD
system. The drug released from such a bioadhesive system can be easily adjusted by:
Figure 14: Two pulse release profile from the Gabapentin BIOROD system. (ALL FIGURES AND TABLES ARE COURTESY OF THE AUTHOR.)
- Variation of the architecture of the inner core
Variation of rate controlling polymers, including type and concentration in the core
- Inclusion of placebo and barrier layers within the core
- Variation of bioadhesive coating shell.
The results and overview presented in this article leave no doubt that bioadhesive-based targeted oral delivery systems have
the potential to enable many drugs to be delivered at the desired absorption site in a prolonged and tailored manner. The
successful fabrication of the bioadhesive system should take into consideration a multitude of aspects of polymer-mucus interactions,
preferred site of absorption, drug loading, GI physiology, dosage form size and shape, and contact duration. Though each of
these factors plays a critical role, optimization must be performed to give the best performance in all categories. Fabrication
of oral bioadhesive formulations for existing drugs potentially provides access to new and expanded markets. Many drugs with
a narrow absorption window that must be administered multiple times per day could potentially be developed into longer-lasting
effective therapies that offer reduced daily administrations, greater patient compliance, reduced maximum plasma–related adverse
effects, and improved intersubject variability. These novel dosage forms may create added value from the existing therapeutic
franchise through the classic marketing strategies of product proliferation. And, finally, at a time when many drug companies
are facing expiration of key patents, new oral bioadhesive formulations with improved performance can provide patent life
extension and facilitate product life cycle management.
Although further research is required, orally administered pharmaceuticals of the future are likely to include bioadhesive
microparticles and nanoparticles that will provide site-specific uptake of drugs and allow tailored drug release to meet biological
needs. With the recent development in nanotechnology, bioadhesive nanodevices offer yet another tool to further expand the
benefits. With the growing realization of the importance of nonspherical-shape particles, the functional behavior of these
bioadhesive carriers can be tuned to optimize their performance in humans (64).
The author would like to thank Dr. George Grandolfi and Aliceann Hagopian for their valuable input.
Avinash Nangia, PhD, is senior vice-president of research and development at Spherics, Inc., 375 Forbes Blvd., Mansfield, MA 02048, tel. 508.452.7000,
fax 508.452.7070, firstname.lastname@example.org
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