Active transport chemical delivery system

Lipids, unlike many excipients, whether present in food or as discreet pharmaceutical additives, are processed both chemically and physically within the GIT before absorption and transport into the portal blood (or mesenteric lymph). Indeed, most of the effects mediated by formulation-based lipids or the lipid content of food are mediated by means of the products of lipid digestion—molecules that may exhibit very different physicochemical and physiological properties when compared with the initial excipient or food constituent. Therefore, although administered lipids have formulation properties in their own right, many of their effects are mediated by species that are produced after transformation or activation in the GIT. An understanding of the luminal and/or enterocyte-based processing pathways of lipids and lipid systems is therefore critical to the effective design of lipid-based delivery systems. 

Bio/molecular delivery systems consist of two key attributes the physico/chemical nature of the transporting vehicle and the method by which the biochemically active molecule is coupled to the vehicle. The former attribute is represented by an extraordinarily wide range of physico/chemical units ranging from integrated parent molecules to submicron particulates. The latter attribute is represented primarily by the process of covalent bonding and more recently non-covalent interactions. I6,i7,i8,i9... 

Most, if not all, of the compounds mentioned in this volume have arisen through the systematic screening of novel chemicals and the identification of active lead compounds. The subsequent development of more active analogues and suitable formulation/delivery systems illustrates the ingenuity and expertise of the R D chemists/biologists involved in the launch of a new herbicide. While this approach has been eminently successful, there is a view that, ideally, novel compounds should be tailored to fit specific enzyme receptor sites. This aim will be achieved only with improved understanding of the molecular architecture of the site(s) and the molecular requirements for transport into and within the plant. The approach taken in this book should serve to illuminate the problems and possible solutions. 

Antibiotic activity and channel replacement therapies are two areas where synthetic ion transport systems show potential. Other applications include drug delivery, chemical sensing, cell signaling, organocatalysis, and material science. The examples of synthetic ion transporters reviewed provide an overview of the successful designs and combinations of ion receptor interactions used to facilitate transmembrane transport. In this regard, important advances have been made in the last decade. There is little doubt that real-world application of these systems will come in the near future. 

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