Phospholipids in pharmaceutical research

Abstract

Peter van Hoogevest On September 16 and 17, 2013 the Third International Symposium on “Phospholipids in Pharmaceutical Research”, biannually organized by the “Phospholipid Research Center, Heidelberg” took place in Heidelberg, Germany. Phospholipid excipients are being used in registered pharmaceutical products worldwide. Because of their physiological occurrence, e.g., as natural membrane components, they are well tolerated, toxicologically harmless and suitable for any administration route. In pharmaceutical technology, phospholipids are used as wetting agents, emulsifiers, and solubilizers. The nature of the polar head group and fatty acid composition determines the physico-chemical properties of phospholipids. Combining the right phospholipid excipient with a drug, to accommodate the intended use and properties of the drug substances, requires a deep understanding of the physico-chemical properties of the phospholipids and their interaction with the physiological milieu. The symposium was devoted to a review of the properties of phospholipid excipients and their rational selection, analysis, and practical uses in formulations dependent on the intended administration route and characteristics of the drug substance. Discussed were the many types of formulations possible, including emulsions, micelles, suspensions, liposomes, wherein phospholipids can be used, and their topical, parenteral, oral, and pulmonary use. The symposium was attended by 168 scientists from academia and industry and the seminars were given by reputed scientists experienced in phospholipid research and development of phospholipid based dosage forms. The symposium served as a platform for enthusiastic discussions and contacts between academia, industry, and regulatory authorities throughout all areas of interests of phospholipid scientists and formulators. Currently, there is much interest in new nano-materials for drug delivery research. These materials (e.g. ZnO, graphite, gold, silver) are mostly not biodegradable and may pose unsurmountable toxicity issues. Phospholipid based carriers (e.g. liposomes and emulsions) are biodegradable and biocompatible and established as drug carriers through pharmaceutical products accepted by regulatory authorities. It is remarkable that especially academic research is focusing on these new non-lipid nanomaterials even though research on liposomes would actually make more sense. This special issue of EJLST is devoted to the Symposium. The selected publications, derived from seminars or posters presented during the symposium, reflect impressively the variety of research aspects typical for pharmaceutical phospholipid excipients which are a gift from nature. The papers also nicely illustrate how the selection of certain phospholipids may be critical for the performance of the phospholipid containing drug formulation and degree and mode of interaction with the biological milieu. An interesting aspect in the liposome research field is the use of phospholipids derived from natural sources like soybean and egg yolk and the use of synthetic phospholipids. Whereas biophysicists tend to prefer synthetic phospholipids with selected, defined fatty composition, pharmacists should preferably use high quality natural phospholipids as phospholipid excipients in their formulations. Also the oral use of phospholipid excipients is a topic of increasing pharmaceutical interest. Phospholipids are essential components of the bile and bile plays a decisive role in the solubilization of fatty food components and lipophilic drugs to enable their systemic absorption. It is therefore obvious that phospholipids have a potential as oral bioavailability enhancer of poorly water soluble, lipophilic drugs. I thank the EJLST for giving the Phospholipid Research Center the opportunity to assemble a special issue devoted to the symposium “Phospholipids in Pharmaceutical Research.” I also thank the authors of the articles in this special issue, which is available online (http://onlinelibrary.wiley.com/doi/10.1002/ejlt.v116.9/issuetoc), for their enthusiastic support and valuable contributions. Peter van Hoogevest