Abstract
Biotechnology has provided a wide array of therapeutic agents such as peptide, protein, vaccine and gene products that are currently mainly administered by means of injections. Therapeutic agents produced by biotechnological processes such as recombinant DNA technology, fermentation, tissue and cell culture technology as well as genetic engineering are usually large, hydrophilic molecules facing delivery challenges, for example, these drugs are susceptible to degradation and are generally poorly membrane permeable. Since successful delivery of any drug is a pre-requisite to achieve the therapeutic goal, novel strategies have emerged in the late 20th century to overcome challenges associated with the oral route of drug administration. These strategies include, but are not restricted to micro- and nanotechnology including self-emulsifying lipid based formulations, dendrimers and devices, permeability enhancing technology, targeting of active transporters and membrane receptors, use of cell penetrating peptides, chemical modifications of peptides such as inclusion complex formation and peptide conjugates, site-specific delivery systems, muco-adhesive systems and polymeric hydrogels. Despite the initial excitement regarding the potential of these technologies to provide effective oral delivery, few have advanced from the pre-clinical stage into clinical trials and very few, if any, resulted so far in registered medicinal products. Moreover, most literature provides information on effectiveness and mechanisms based on in vitro investigations without revealing the viability of these technologies in clinical practice. Although this topic of oral peptide delivery has gone through different phases in terms of attracting attention from the scientific community, it remains a timely research subject. The therapeutic benefits to patients and potential economic benefits to the producer serve as the driving forces behind finding an effective oral delivery system for biotechnology derived drugs. This special issue aims at assessing some of the latest developments in the field of oral delivery of biotechnological therapeutic agents. The reader will not only gain an understanding of the challenges associated with oral delivery of protein and peptide based drugs, but certain strategies that emerged to overcome these drawbacks are also discussed. From the discussions it is clear that scientific research has contributed to a deeper understanding of older drug delivery strategies, while new discoveries keep the vision of producing an effective oral peptide drug delivery system alive.