Biomedical Engineering Reference
In-Depth Information
oral doses of these nanoparticles formulation was administered every 10
th
day which in turn resulted in absence of tubercle bacilli in the meninges,
on the basis of CFU and histopathology [114].
Niosomes can also be used as an alternative to liposomes for specii c tar-
get drug delivery. h ey are basically thermodynamically stable liposomes
like vesicles produced by the hydration of cholesterol and charge induc-
ing components such as charged phospholipids (e.g. Dicetylphosphate
and stearyl amine) and non ionic surfactants (e.g. monoalkyl or dialkyl
polyoxyethylene ether) [115]. Micron sized RIF loaded niosomes contain-
ing Span-85 as surfactants were prepared by the Jain and Vyas [116]. As
a result upto 44% of the drug was localized in the lungs by adjusting the
size of the carrier. h e same group of the scientist further extended their
studies to investigate the biodistribution of niosomes of smaller sizes with
the dif erent sorbitan esters (Span 20, 40, 60, 80 and 85) and cholesterol
in 50:50 mol fraction ratios [117].
In vitro
studies showed 80% maximal
and 52% minimal levels for Span-20 and Span-85 based systems. All these
studies led to the conclusion that more lipophilic the surfactant, slower was
the drug release in the aqueous medium.
Nanoparticles of size 250 nm were used for delivery of the anti-TB
drugs such as isoniazid, rifampicin and streptomycin. h e accumulation
of these drugs was checked in human monocytes as well as thieir antimi-
crobial activity against
M. tuberculosis
residing in the human-monocyte
derived macrophages. h e result was that the intracellular concentration
of the free INH was equal to or slightly higher than that of the extracellular
l uid [118].
14.4
Cancer & Tumor Targeting Nanoparticles
Nanoparticles are very well suited materials for targeted tumor delivery
because of their ability to circulate in the bloodstream for relatively longer
period of time as well as their ability to accumulate in the tumor spaces.
Some of the
in vivo
and
in vitro
experiments have shown nanoparticles to
be fruitful for the tumor treatment. h ere is a growing evidence which sug-
gests that many nanoparticles accumulated at the tumor site is indepen-
dent of the presence or absence of the targeting ligand. In many studies,
nanodelivery systems with target ligands have shown better performance
than non-targeted system
(
Figure 14.7, below)
.
h ese entire conclusions
led to the improvement in the performance of the nanoparticles asso-
ciation with target cell membranes and target cell internalization. EPR
(enhanced permeability and retention) ef ect is one of the dominating
