Results and discussion
Characterization of ODTs.
Figure 2 is an overview of tablet disintegration time. The different graphs represent different disintegrant use levels,
from 0.5% to 20%. Within each graph, the x-axis is the four disintegrants studied, the y-axis is the five compaction forces
(4kN–12kN), and the z-axis is tablet disintegration time. In the first graph, a control sample without any disintegrant was
included. The results indicated that Ac-Di-Sol disintegrates ODTs much faster than crospovidone (both PVP XL-10 and Kollidon
CL-SF (crospovidone, BASF, Ludwigshafen, Germany)) and Glycolys (sodium starch glycolate, Roquette, Lestrem, France) at a
low use level (≤2%). Crospovidone starts to perform at 5% and beyond. Glycolys is less potent than Ac-Di-Sol at low use level
and less potent than crospovidone at a high level.
In fact, at a low use level (0.5–2%), Ac-Di-Sol was the only disintegrant among the three types that could effectively disintegrate
tablets at all compaction force ranges. Even when the use level increased to 2%, Ac-Di-Sol was still the only disintegrant
that could provide ODTs that meet the USP-required 30 s disintegration time at all compaction force ranges (see Figure 3).
Figure 3: Tablet disintegration time at 2% disintegrant use level. Ac-Di-Sol is crosslinked croscarmellose sodium, PVP XL-10
is crospovidone, Kollidon CL-SF is crospovidone, and Glycolys is sodium starch glycolate.
Figure 4 provides an overview of tablet-crushing strength for all disintegrants at different use levels (0.5%–20%) and compaction
forces (4kN–12kN). Within each graph, the z-axis is the tablet-crushing strength. Results showed that disintegrants had no
impact on tablet-crushing strength when the disintegrant use level was ≤ 5%, as the tablet-crushing strength was similar to
the control sample at all compaction force ranges. However, tablet-crushing strength started to decrease when the disintegrant
use level was ≥ 8%; the tablets became softer. In addition, tablet friability data (see Figure 5) further confirmed the tablet-crushing
strength conclusions (e.g., tablet became friable if the disintegrant use level reached or exceeded 8%).
Figure 4: Tablet-crushing strength overview.
For each disintegrant, an optimal use level was identified. The optimal use level is defined as the lowest use level that
can achieve the fastest disintegration time over the range of compaction forces studied for that particular disintegrant.
The optimal use level for Ac-Di-Sol is 2%, for PVP XL-10 and Kollidon CL-SF is 5%, and for Glycolys is 5%. Figure 6 is a summary
graph of the optimal disintegrant use level versus disintegration time for tablets with a 70–80N crushing strength. In general,
at each disintegrant's optimal use level, 2% Ac-Di-Sol could disintegrate tablet at the same fast speed as 5% PVP XL-10 and
5% Kollidon CL-SF, and they all outperformed 5% Glycolys.
Figure 5: Tablet friability overview.
Figure 7 is an overview of tablet stability in terms of its disintegration time. The x, y, z axis are the same as Figure 2.
Bar graphs and cylinder graphs represent 24-hour and 4-month disintegration time data, respectively. Overall, disintegration
time of all tablets slightly increased after 4 months of storage in ambient conditions within sealed plastic bags. However,
no stability difference was found among different disintegrants. The slight disintegration time increase came from case hardening
of the model mannitol tablet. All tablets became harder over storage (e.g., tablet-crushing strength increased for all tablets).
Figure 6: Tablet disintegration time comparison at optimal use level (tablet-crushing strength: 70~80 N).
Triangle mouthfeel study of ODTs.
In terms of mouthfeel of ODTs that contain 2% Ac-Di-Sol versus ODTs that contain 5% PVP XL-10, 15 panelists provided
the correct judgment out of the 34 panelists. This means 15 panelists picked out the correct odd sample, while the other 19
panelists picked out one of the two identical samples instead of the real, different one. According to the statistical table
provided by Meilgaard et al. (10), a minimum of 17 correct judgments was required to establish significance at 95% probability
level. A minimum of 19 correct judgments was required to establish significance at 99% probability level. The conclusion from
this triangle mouthfeel study, therefore, was that there is no significant statistical difference between ODTs that contain
2% Ac-Di-Sol and ODTs that contain 5% PVP XL-10 in terms of mouthfeel.
Figure 7: Stability study of tablet disintegration time: 24 h (bar graph) versus 4 months (cylinder graph).