The chapters in this volume describe a powerful emerging approach for
the therapy of disease. Targeted drug delivery, that is control of the
kinetic behavior, tissue distribution, and subcellular localization of
pharmaco- logically active agents, offers an important means for
improving the efficacy of a wide variety of drug therapies. This is
particularly true for therapeutic approaches based on newer agents which
are the products of recombinant DNA research. These agents, be they
peptides, proteins, or oligonucleotides, tend to be larger, more
complex, and less stable than traditional drugs. Thus they stand to
benefit most from drug delivery systems which can protect them from
premature degradation and which can carry them to critical target sites
in the body. This volume examines several important aspects of the
current state of drug delivery research; it also attempts to project
future directions for this field. Successful approaches to drug
targeting are based, first of all, on a sophisticated understanding of
the biological barriers encountered by the drug-carrier complex as it
moves from the portal of administration to the ultimate target site. A
second aspect of successful drug delivery is appro- priate matching of
the disease entity with the pharmacologically active substance and with
the delivery system. Thus it is important to be aware of the variety of
delivery technologies which currently exist and to be sensitive to their
strengths and limitations.