Biomedical Engineering Reference
In-Depth Information
FIGURE 1.4
Schematic diagram of NMs that are used for targeted drug delivery (green sphere—
fluorescent NMs; gray sphere—nonfluorescent NM).
(For interpretation of the references to color
in this figure legend, the reader is referred to the online version of this topic)
the functions they are designed for. Excellent candidates for drug delivery pur-
poses must be small (less than 100 nm), nontoxic, biodegradable, biocompat-
ible, does not aggregate, avoids the reticulo-endothelial system (RES) uptake,
and escapes opsonization, noninflammatory, with prolonged circulation time
making the drug more efficient for therapy and, therefore, more cost effective.
Many drugs in the market that are now available for human use are already
nano-enabled. The ability of these drugs to minimize the side effects that are
normally observed in conventional drugs opens up doors for applications of
NMs as safer alternatives to drug delivery. Aside from the requirements of size,
charge, shape, surface modifications, loading, and other chemical properties to
effectively deliver drugs using the NM carrier systems other challenges need
further attention. These studies need to focus on the interaction of NMs and
their hosts in terms of biodistribution, organ accumulation, degradation and/
or toxicity, damage of cellular structures or inflammatory foreign body effects,
and genetic damage. It is essential to investigate the possible adverse effects
or toxicity of nanocarriers.
231-233
But, the NM drug delivery system is still in
its infancy. Research protocols like absorption, distribution, metabolism, and
elimination (ADME), and drug metabolism and pharmacokinetics (DMPKs)
will definitely be part of further studies on NM drug delivery systems in the
future
184,234,235
. The PKs and excretion routes of the various NMs used as drug
delivery systems demand exhaustive research. The path that the nano-enabled
drugs take after entry into the living system depends on many factors. The NM
properties that allow its in vivo imaging may be the most useful property for
elucidating the ADME and PK in nanodrug delivery systems.
