Biomedical Engineering Reference
In-Depth Information
size of proteins is also a major constraint that makes this method unsuitable for oral
delivery.
A plethora of research work has been conducted to overcome this problem.
Absorption enhancers have been used to improve the oral delivery of proteins. Drug
delivery systems like micro- and nanoparticles are currently being investigated for
improving protein delivery. A great deal of attention has been focused on exploring
gut-associated lymphoid tissue (GALT) or Peyer's patches of the intestine as poten-
tial targets of proteins and peptides. Peyer's patches have many advantages to offer
for protein delivery, such as bypass of first-pass metabolism and high phagocytic
activity. This tissue has been successfully used for absorption of orally delivered pep-
tides like glucagon.
The presence of IgA-committed cells in Peyer's patches makes them useful for trig-
gering antigenic reactions, rendering them of potential use in oral vaccine delivery.
In spite of many advancements in the oral delivery of proteins, their physicochem-
ical properties and tendency to aggregate in the presence of chelating agents limit the
usefulness of this route.
8.8.5 Transdermal Delivery
Salient advantages associated with the transdermal delivery of proteins are the
noninvasiveness of route, bypass of first-pass metabolism, controlled delivery, and
improved patient compliance. Mechanical techniques like iontophoresis and sono-
phoresis have been worked out to achieve this aim. These techniques have been suc-
cessfully used for the delivery of insulin, calcitonin, leuprolide, and so forth.
8.9 Regulatory Perspectives of Protein and Peptide Drug
Development
The introduction of recombinant DNA technology-based protein and peptide prod-
ucts has been receiving impetus not only from scientists in areas of major research
but also from regulatory bodies. Globally acclaimed regulatory bodies like the United
States Food and Drug Administration (USFDA) and other similar organizations have
put in relentless efforts to introduce protein and peptide drugs based on recombinant
genetic and hybridoma technologies. In addition, it has been on the FDA's agenda
not only to bring more recombinant protein products onto the market, but also to
improve old peptide drugs and develop more innovative routes for their drug delivery
along with reducing their immunogenic potential.
Until the later quarter of the twentieth century, the majority of proteins and
peptides used in therapeutics were obtained from natural sources. A couple of
well-known examples are insulin and gonadotrophic hormones, which are well docu-
mented in the literature. Most of these proteins and peptides are obtained from ani-
mal sources. The major shortcomings of such proteins and peptides are their source,
difficulty in their purification, inability to administer them by the oral route, and
potentially dangerous errors in their composition.
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