Chapter 4: Phage-mediated Drug Delivery

The creation and maintenance of a drug's therapeutic concentration at its site of action has presented a pharmacological dilemma for decades. Circumventing this problem involves either creating drugs that are more target-specific or modifying existing drugs so as to result in preferential localization in target tissue. Drug delivery systems are characterized by both the drug carrier and the targeting moiety. Antibodies have been, so far, the mainstay of targeting ligands. However, problems associated with their use has allowed the emergence of peptides as a new generation of ligands. Further, the availability of phage display libraries permit high throughput selection of target-specific peptide ligands. Apart from being a source of targeting ligands, phage itself serves as an excellent vehicle for drugs. This chapter provides examples of the use of phage particles and phage components as mediators of drug targeting. Also, details of an approach in which the target-specific phage major coat protein is utilized as a liposomal ligand will be discussed in depth.