Chitosan Loaded Mucoadhesive Microspheres of Gliclazide - Journal

Prakash Rao B et al./ Formulation and Evaluation of Mucoadhesive Buccal Drug Delivery System of Metoprolol Tartrate by Using Central Composite Design
negative effect and factor B has more significant negative
effect than that of factor A on percentage MT release at 8
hours. In another words, at high level of A percentage release
has high value at all level of factor B which indicates factor A
helps more release of drug.
Effect of Variables on Bioadhesive Strength
Bioadhesion is generally understood to define the ability of a
biological or synthetic material to “stick” to a mucous
membrane, resulting in adhesion of the material to the tissue
20
for a protracted period of time . In general, bioadhesion is
considered to occur in three major stages: wetting,
interpenetration, and mechanical interlocking between
22
biological tissue and polymer . Several polymer and
hydrophilic macromolecules containing groups able to form
hydrogen bonds have showed good adhesion property that
seems to be enhanced by the incorporation of amine and
23
carboxylic groups . The strength of bioadhesion is affected
by various factors such as molecular weight of polymer,
contact time with mucus, swelling rate of polymer, and
22
biological membrane used in the study . Water uptake
process produces polymer swelling and improves the
consolidation step that increases the mobility of molecules
and facilitates that interpenetration with the biological tissue
layer. So, the polymer swelling is a property related to the
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bioadhesion of the system . The constant and regression
coefficient for bioadhesive strength are as follow:
R = + 26.40149 + 0.066170 * A + 0.064012* B + 5.42857E-
2
004 * A * B
The linear model F-value of 6.54 and p value 0.0122 implies
the model is significant. Values of "Prob > F" less than 0.0500
indicate model terms are significant. In this case (Table 4) A,
cabopol and B, HPC are significant model terms . (Fig. 7) rep
resent the observed response values compared to that of
predicted values. The effect of A and B can be further
elucidated with the help of response surface plot (Fig 8). Both
the factor A and B have an synergetic effect on the
bioadhesive strength as AB factor has positive effect. At high
level of factor A gave slightly higher value of bioadhesive
strength than that of factor B. If A kept high level and at all
levels of B bioadhesive strength was observed slightly higher
values.
As increase the concentration of factor A and B increases the
bioadhesive strength. Carbopol gives slightly higher
bioadhesive strength, when compare to the HPC due to high
molecular weight, water dispersibility, polymer chain
flexibility for chain interpenetration and diffusion with mucin.
The carbopol forms hydrogen bond with mucin due to the
21
presence of many carboxylic groups and its shows higher
bioadhesive strength than HPC.
151
Effect of formulation variables on T 50%
The value of T ranges from the 4.17 to 6.46 hours (Table 4).
50%
The increased T was observed at high concentrations of
50%
polymers. The constant and regression coefficient for R3 T
50%
are as follows:
R = +3.25759 + 0.012952*A + 0.01551*B
3
The linear model was found to be significant for the time for
50% of drug release. The Model F-value of 48.90 and value
of p is less than 0.000100 indicate the model is significant.
Lack of fit for the model is not significant as F-value is 1.42
and p value is 0.3817. Both the factors have positive effect
Fig. 7: Correlation between actual and predicted values f
or bioadhesive strength
Fig. 8: Response surface plot showing the effect of factor
A (carbopol) and factor B (HPC) on bioadhesive strength
RJPS, Jul - Sep, 2011/ Vol 1/ Issue 2