Gastrointestinal delivery of peptide and protein drugs to aquacultured teleosts

While one of the major roles of the vertebrate gut is to exclude antigens, it is generally accepted that a proportion of ingested protein is absorbed in an intact form and as small peptides. This review briefly examines the evidence for the occurrence of intact protein and peptide uptake in fish. Consideration is given to the mechanisms of absorption of macromolecules and an outline of the possible physiological function of the phenomenon over-viewed. The application potential of this natural occurrence to the oral delivery of production-oriented bioactive peptide and protein drugs is considered with reference to growth, reproduction and immunomodulation. Attention is drawn to specific methods which have been examined as a means of protecting macromolecules from the degradative action of the gut (e.g., anti-proteases, antacids) and or enhancing their uptake (e.g., mucosal modifiers). Finally, areas which offer potential for future research effort are presented, including consideration of design concepts for oral delivery methods and the need for increased understanding of the pharmacokinetics of production-related peptide and protein drugs. (C) 1999 Elsevier Science B.V. All rights reserved.