Mucoadhesive strength of PSY and TPSY gels was assessed using modified physical balance method.
Figure 1(a) exhibits the FT-IR spectrum of PSY and TPSY in the frequency region from 4000 to 500 [cm.sup.-1].
Figure 1(b) shows the TGA and DSC thermograms of PSY and TPSY. The DSC curve of psyllium shows a broad endotherm at 70.29[degrees]C with heat of fusion of 181.3 J/g followed by an exotherm at 308.50[degrees]C with heat flow of 240.1 J/g.
Figure 1(c) displays the X-ray diffraction spectra of PSY and TPSY. X-ray diffractogram of PSY is typical of amorphous materials with no sharp peaks while the diffractgram of TPSY shows two characteristic sharp peaks at 32[degrees] and 45[degrees] (2[thete]) which indicates slight increase in crystallinity of PSY on thiolation.
Figure 2 shows the shape and surface morphology of PSY and TPSY, examined under a scanning electron microscope.
Swelling power studies conducted on PSY and TPSY revealed that 1g of PSY and TPSY on hydration in water swells to 86.6 and 100 mL, respectively.
The mucoadhesive applications of synthesized TPSY were comparatively evaluated by formulating gels of PSY and TPSY employing metronidazole as the model drug.
Table 1 summarizes the results of mucoadhesive strength, ex vivo bioadhesion, and swelling studies conducted using metronidazole-loaded PSY and TPSY gel.