Preface
Chitosan-based formulations of drugs, imaging agents and biotherapeutics
☆
Chitosan is a polysaccharide [α (1-4) 2-amino 2-deoxy β-
D
glucan]
obtained by deacetylation of chitin [(1-4) 2-acetamido 2-deoxy β-
D
glucan], a waste product from seafood industry, which has been
extensively studied as a biomaterial and as a pharmaceutical excipient
in drug formulations [1–3]. It is a biocompatible polymer with low
toxicity. Chitosan is insoluble in water at neutral pH but soluble under
slightly acidic conditions (pH <5) because of protonation of the
amine groups. This soluble, cationic polymer interacts with mucus
and/or cell membranes and also increases the paracellular perme-
ability of the cell linings [2,4,5]. Chitosan's primary amine groups as
well as the hydroxyl groups allow chemical derivatization by which
the properties of this polymer can be modulated and adjusted to the
aimed application. This has resulted in a large variety of chitosan
derivatives with different physical and biological properties, such as
improved solubility, permeation enhancement, use as an adjuvant,
etc. Chitosan and its derivatives have been studied for formulations
that enhance the absorption of macromolecular therapeutics (pep-
tides, protein therapeutics and antigens as well as plasmid DNA)
[2,3,5–7], and for the preparation of particulate drug targeting
systems [8–10]. Chitosan is a very ‘popular’ polymer in the drug
delivery research field as reflected by the growing number of
published papers (Fig. 1).
This special Advanced Drug Delivery Reviews issue on ‘chitosan-
based formulations of drugs, imaging agents and biotherapeutics’
summarizes recent progress and different applications of chitosan-
based formulations.
The first chapter by Kean and Thanou gives an overview about
(bio)degradation, biodistribution and toxicity of chitosan-based
delivery systems as well as current status of chitosan drug formula-
tions in the clinic. The authors provide information on the biological
properties that affect chitosan's safe use for drug delivery.
The next three chapters deal with applications of chitosan-based
formulations for delivery of nucleic acids, small drugs and imaging
agents, particularly upon systemic administration. In chapter two, Mao
et al. review chitosan-based formulations for delivery of pDNA and
siRNA and discuss the current challenges and factors affecting the
efficiency of these systems. Targeted delivery of small drugs using
chitosan-based formulations is described by Park et al. in chapter three.
The first part of this review focuses on the recent developments of
targeted drug delivery carriers for cancer therapy. The second part of
this contribution considers organ-specific delivery of low molecular
weight drugs using chitosan and its derivatives. In chapter four, Agrawal
et al. give a short overview of molecular imaging technologies and
discuss recent applications of chitosan-based nanoparticles in this field.
Chitosan and its derivatives, because of their excellent mucoadhe-
sive and absorption-enhancing properties, have been extensively
studied for delivery of therapeutic proteins and antigens. The chapter
by Amidi et al. summarizes recent progress of chitosan-based
formulations and delivery of both therapeutic peptides/proteins and
antigens through parenteral and mucosal (particularly nasal and
pulmonary) routes. The last two chapters of this issue deal with
chitosan-based formulations for local delivery of drugs. In chapter six,
Bhattarai et al. review the developments in chitosan hydrogels for
local protein delivery. Recent developments of chitosan nanosystems
for delivery of hydrophilic and lipophilic drugs and polynucleotides
into the eye surface are reviewed in the last chapter, contributed by de
la Fuente et al.
It should be noted that chitosan-based formulations for oral drug
delivery and chitosan-based materials for tissue engineering are not
covered in this issue, since excellent reviews on these topics have
been published in recent years [11–15].
All contributors of this special issue invested their costly time and
energy to submit excellent chapters. We, as theme editors, appreciate
their efforts and enthusiasms. We also would like to thank Mr Haobai
Li, Miss Brigitte Neilson (Elsevier) and Dr Hamid Ghandehari (ADDR
executive editor) for their enormous help, input and support. Finally,
we like to thank the reviewers for critically reading the manuscripts
and coming up with remarks, comments and suggestions to improve
the readability and quality of the manuscripts. We hope and expect
Advanced Drug Delivery Reviews 62 (2010) 1–2
Fig. 1. Number of publications on chitosan in drug delivery.
☆
This preface is part of the Advanced Drug Delivery Reviews theme issue on
“Chitosan-Based Formulations of Drugs, Imaging Agents and Biotherapeutics”.
0169-409X/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.addr.2009.12.006
Contents lists available at ScienceDirect
Advanced Drug Delivery Reviews
journal homepage: www.elsevier.com/locate/addr