Management of illness through medication has entered a new era in which an enormous number of biotechnology based products, peptides / proteins pharmaceuticals are available / synthesized for therapeutic use. The growing interest can be ascribed to the increased understanding of their role in physiology and therapy as well as the established capability of producing large quantities with consistent quality by the biotech route. As technological innovation spreads throughout medicine so does the "cutting edge" come to drug delivery systems alias ‘Mucoadhesive Drug Delivery’.
Some examples of this system include, the BioErodible MucoAdhesive (BEMA) delivery system is designed to deliver either local or systemic levels of drugs across mucosal tissues. This delivery system offers rapid onset of action and improved drug bioavailability compared with the oral route. As an added benefit, drug inactivation by first-pass metabolism in the liver is avoided. The BEMA delivery system consists of a dime-sized disk with bioerodible layers that delivers drugs rapidly over specified time intervals. The erosion rate is controllable, and there is no residue to remove and so far has shown promise for the administration of pain medications, antiemetics, and antimigraine drugs (Clinical Trials, 2008, February).
One example of this technology is the BEMA Fentanyl mouth patch from BioDelivery Sciences International (Raleigh, NC), which is currently in phase III trials. It is designed to assist with breakthrough cancer pain for opioid-tolerant patients. Dr. James North, MD, principal investigator for the phase III efficacy study reports, "Breakthrough cancer pain can be devastating to patients with cancer and their families. Patients suffering from breakthrough cancer pain need treatment options that provide effective pain relief and are easy to administer" (Triangle Business Journal, 2009, May) .
Mucosal drug delivery technologies are expanding exponentially with applications in every imaginable route of administration because of the indisputable therapeutic benefit this delivery technology brings. Benefits include site-specific targeting, less frequent dosing, and maintaining effective plasma concentration without increased consumption.
The global market for advanced drug delivery systems was more than € 37.9 billion in 2000 and is estimated to grow and cross € 95 B (i.e., controlled release €19.8B, needle-less injection € 0.8B, injectable /impantable polymer systems €5.4B, transdermal € 9.6B, transnasal €12.0B, pulmonary € 17.0B, transmucosal €4.9B, rectal €0.9B, liposomal drug delivery € 2.5B, cell/gene therapy € 3.8B, and balance covered by miscellaneous ).
The objective of this series of review articles is to understand the opportunities available to delivery peptides and protein molecules as mucosal DDS and the complexities associated with the formulation thereof.
The development of delivery systems for therapeutic peptides and proteins and their evaluation depend on the biophysical, biochemical and physiological characteristics of the peptide molecules including their molecular size, bio half-life, immunogenecity, conformational stability, dose requirement, site & rate of administration, pharmacokinetics and pharmacodynamics. The immunogenic potential of any impurities or the peptide molecule itself must also be taken into consideration. Since, peptides are complex structures and exhibit anomalous behavior (against conventional drug moieties) to environmental conditions; the study of its chemistry, preparation, purification etc. before dosage form design (since these parameters affect its stability on shelf) becomes vital.
To begin with, in the next chapter, let us first understand the chemistry and the complexities of peptides and formulation considerations of peptide based therapies employing mucosal routes of administration.