Biomaterial-Based Particulate Drug Carriers - Harnessing Biomaterials in Nanomedicine: Preparation, Toxicity, and Applications - page 5

an aqueous core; particles in which both the shell and the interior are
made from the same material and that may contain water molecules
in their interior in nano or microchannels rather than a phase or
core; two new types of particulate drug carriers, developed by our
group, that do not fall strictly into the previous two sub-categories.
These will be introduced and discussed in later sections of this
chapter [11-15].
In the remainder of this chapter, we will focus solely on particulate
carriers.

1.1.4 Carrier-Mediated Drug Targeting

Even simple searches within scientific databases, using the term
“drug targeting” alone or with additional key words, yield many
results. It may, therefore, seem that the goal of drug targeting, whether
for a free drug for a drug-carrier system, has been achieved long ago
and is no longer an issue. The reality is quite diff erent — achieving
drug targeting is still an elusive goal and a significant challenge.
The definition of drug targeting is delivery of the drug exclusively
to its molecular sites of action. By its very nature, drug targeting is
relevant to living systems, not — as will be further discussed — to
cell cultures. Striving for drug targeting can be divided into three
steps, as illustrated in Figure 1.4:
In the first step , which is relevant to systemic administration,
the drug has to reach the anatomic location where the pathological
state resides. For example, if the intent is to deliver an antibacterial
agent for the treatment of lung bacterial infection and the drug is
administered intravenously (IV), the first step means reaching from
the systemic port of entry to the lungs.
In the second step the drug has to reach, within that anatomic
location, the specific region where its sites of action reside.
Continuing with the example of lung bacterial infection, once the
drug has reached to lungs, it has to get as close as possible to the
bacterial colonies there. In cases of local administration, the drug
is delivered directly to the anatomic locations, and one could view
it as either achievement or circumvention of step 1. In further
continuation of the lungs example, local administration could be by
the pulmonary, rather than the IV route. For drugs, small or large,
that operate outside the target cell, such as on receptors harbored
by the cell membranes — achievement of the second step suffices to