Drug Targeting Organ-Specific Strategies

Foreword
Drug Targeting Organ-Specific Strategies. Edited by G. Molema, D. K. F. Meijer
Copyright © 2001 Wiley-VCH Verlag GmbH
ISBNs: 3-527-29989-0 (Hardcover); 3-527-60006-X (Electronic)
It was in the mid-1970s I think, just a few years after Brenda Ryman and I introduced liposomes
as a drug delivery system, when a well meaning colleague af mine advised me not to
put all my eggs in one basket.The eggs were liposomes and the basket my career.At the same
time there were all sorts of prophecies and rumours from a variety of quarters about liposomal
stability problems, expense, toxicity, difficulties with large scale manufacture, etc. Some
went as far as to dismiss the system as a flash in the pan phenomenon. Indeed, the yellow
brick road to the magic bullet is littered with systems that once made the headlines and then
fell by the wayside. So, such comments on liposomes, and later on on antibodies, were not surprising.
I believe that what made many of us persevere throughout the decades in developing
drug carrier systems such as liposomes, and associated technologies was the realization that,
for the foreseeable future at least, molecular modelling is not the answer to drug selectivity
for most therapeutics. The vagaries of the biological milieu in vivo ensures that optimal drug
action (seen in the test tube) is compromised by such factors as opsonins and proteolytic enzymes
in the bloodstream, membrane barriers, loss through the kidneys, and premature interception
of therapeutics by the reticuloendothelial system. In the case of liposomes, monoclonal
antibodies and some polymers, carrier development was greatly facilitated by their
structural versatility which enabled the design of advanced versions of unique sophistication.
The first generation of liposome-based systems approved for clinical use are believed to
function on the basis of their passive uptake by the target tissues (e.g. the AmBisome and the
virosome vaccine Hepaxal) or by avoiding certain tissues (e.g. heart, kidneys) that are prone
to damage by the drug when given as such (e.g. Doxil, Daunoxome). The next challenge is to
create or build on the systems that can be actively targeted to specific tissues or circulation
cells for which systems such as liposomes have little or no affinity. They include a variety of
molecules with genuine targeting properties, for instance (neo-) glycoproteins, monoclonal
antibodies and fragments thereof, applied either as a means to deliver drugs attached to these
biopolymers, or as homing devices when attached to the surface of other drug delivery systems,
for instance liposomes and other particle-type carriers. Success to that end will greatly
enlarge the spectrum of therapeutics that can be selectively delivered, and widen the range
of applications.
In this respect, Grietje Molema, Dirk K. F. Meijer and a team of drug delivery experts have
taken an important step with the present book. Unlike previous volumes, this one is not devoted
exclusively to liposome or antibody technologies. Rather, the book deals with organspecific
drug targeting strategies developed for the treatment of a wide spectrum of diseases
and includes a collection of novel techniques applied to drug targeting research. Thus, the
book provides a blueprint for both the experienced and the semi-experienced reader interested
in drug targeting and related optimization strategies.
London, 2001 Gregory Gregoriadis