Biomedical Engineering Reference
In-Depth Information
on subcutaneous administration (10-200 mg/kg) [32]. Anorexia and
mortality were observed in dogs given doses above 50 mg/kg and above
150 mg/kg, respectively. From the i ndings of autopsy, severe hemorrhagic
pneumonia was observed in all dead dogs. In hematologic i ndings, leu-
kocytosis and increase of serum LDH-2 and LDH-3 isoenzymes were
characteristic.
With clinical trials of dietetic applications of chitosan, its ef ects on
oral administration have been widely reported. To review ef ects of inter-
vention on outcome of adverse ef ects, Jull,
et al.
, reviewed combined
data from the 13 trials [33]. It showed that there were no clear dif er-
ences between intervention and control groups in terms of frequency of
adverse events. Common side ef ects reported in most trials included
constipation, nausea, bloating, indigestion and abdominal pain, but only
two studies found that these were signii cantly increased in participants
taking chitosan. In addition to general side ef ects, some trials monitored
changes in blood chemistry or fat-soluble vitamin levels, but none found
any signii cant ef ect of chitosan on these parameters. However, Tanaka
and colleagues cautioned that special care should be taken in the clinical
use of chitosan over a long period of time, due to possible disturbances
in intestinal microbial l ora [34]. Concerns have also been raised that
chitosan could cause the loss of fat-soluble vitamins; decrease mineral
absorption and bone mineral content and block absorption of certain
medicines [35].
h e testing of cosmetic preparations of Hydagen CMF on the skin of
volunteers revealed favorable properties of high MW chitosan when ery-
thema and squamations were evaluated [36].
6.4
Chitosan as Antimicrobial Agent
One of the most unique biological properties of chitosan is its antibac-
terial activity. h e spectrum of antimicrobial activity of chitosan and
its derivatives extends to include i lamentous fungi, yeasts and bacte-
ria. Many representative examples are given in Table 6.2. h e minimum
growth inhibitory concentrations of chitosan against
Escherichia. coli
and
Staphylococcus aureus
have been 20 ppm, while those against various bac-
teria are 10-1000 ppm. But concentrations reported to be required for
activity against the same specii c target organism can vary up to 500-fold
[37]. h e vast variability in reported data, relying on
in vitro
investigations
is due to intrinsic factors related to chitosan itself as molecular weight
(MW), degree of polymerisation (DP), degree of deacetylation (DDA) and
