Since, peptides are highly potent, their delivery systems must be extremely precise in the rate of delivery. Furthermore, the delivery pattern must be properly designed to suit the pattern and mechanisms of the pharmacological action of the therapeutic peptides and proteins to be delivered. Also, the peptide therapy generally is chronic. Moreover, the rapid disappearance of most peptides from body owing to their degradation by proteolytic enzymes mandates implementation of a therapeutic regimen that requires multiple daily injections to maintain therapeutic efficacy. With high bioavailability reportedly achieved by parenteral administration, needle phobia a difficult parameter to monitor in the clinical setting, pharmaco economics and best clinical practitioners are progressing towards user friendly, effective and non-invasive mucosal drug delivery presentations of medicinal compounds. Because of this, the commercial success of using peptides and proteins as drugs depends on the development of new routes and methodologies for effective administration of these moieties.
The rapid growth in the development of peptide and protein therapeutics over the past decade has presented many formidable challenges to pharmaceutical industry. The early problems of bulk protein production, purification and analytical method development have largely become manageable. What remains, however is one of the most difficult challenges the development of alternate delivery routes for these macromolecular drugs.
Unlike most low molecular weight organic drugs where oral administration is feasible, the delivery of peptides and proteins by oral route is not yet possible. Due to their instability in the gastro intestinal tract and their high degree of hydrophilicity, proteins and peptides are delivered almost exclusively by the parenteral route of administration. There are many disadvantages to chronic injectable therapies. Chief among these are limited patient compliance, minimal pharmacokinetic control and tissue necrosis. In order to increase the therapeutic acceptance and competitiveness of protein therapies, non-invasive modes of administration are needed. Major efforts are underway to explore transdermal, oral, pulmonary and nasal delivery of protein and peptides in therapeutics.
The present article focuses on the potential routes of peptide delivery, their advantages, limitations and feasibility of use.
POTENTIAL ROUTES FOR MUCOSAL DELIVERY OF PEPTIDE PHARMACEUTICALS-
Muco (Bio) adhesion may be defined as the state in which two materials, at least one of which is of a biological nature, are held together for extended periods of time by interfacial forces. For drug delivery purposes, the term Bioadhesion implies attachment of a drug carrier system to a specific biological location. The biological surface can be epithelial tissues, or the mucous coat on the surface of a tissue. If adhesive attachment is to a mucous coat, the phenomenon is referred as mucoadhesion.
The mucosal layer lines a number of the body including the gastrointestinal tract, the urogenital tract, the ear, nose and eye. These represent potential sites for the attachment of any bioadhesive system and hence, the mucoadhesive drug delivery system includes the following:
- Buccal Delivery System
- Oral Delivery System
- Vaginal Delivery System
- Rectal Delivery System
- Nasal Delivery System
- Pulmonary Delivery system
- Colon targeted Delivery system
- Ocular Delivery System
The most recent being use of nanotechnology in the development of mucosal DDS.
In the next chapter let us discuss in detail each of the above mucosal DDS.
For an expert opinion on formulation development of peptide/ protein molecules, please contact Shruti.