A disintegration test was performed using standard disintegration test apparatus (model ED2, Electrolab, India) at 37 °C
in 900 mL of distilled water for six tablets in accordance with USP 24 (19).
In vitro dissolution study.
An in vitro dissolution study of the tablets was carried out in phosphate buffer (pH 5.8, 900 mL, 37 ± 0.5 °C) using USP 23 paddle apparatus (50 rpm). Samples (5 mL) were withdrawn at predetermined time intervals, filtered through 0.45 αm filter,
and assayed at 246 nm using a UV–vis spectrophotometer (Jasco V530, Japan) to determine the percentage of drug released. The
same volume (5 mL) of fresh dissolution medium (37 ± 0.5 °C) was replenished immediately after the sample was withdrawn (20).
Results and discussion
Analysis of the data.
The response parameters were fitted to a first-order polynomial model Y = B
0 + B
1 + B
2 + B
4 + B
5 + B
6 by performing multiple linear regression analysis using Design Expert 7.13 trial (Statease stastical software package). ANOVA
was performed on the response parameters to identify the statistically significant factors (see Table IV).
Table IV: Regression analysis data for the parameters evaluated as per Plackett-Burman experimental design.
Evaluation of agglomerates. Angle of repose (Y
1). Regression analysis showed that acacia has the highest effect on angle of repose, but the value of its coefficient is positive,
which indicates that as the amount of acacia increases, the value of angle of repose increases, resulting in poor flow. Starch
was the best in improving the flow properties. Although the remaining four excipients had similar effect in improving the
flow properties, the effect was less pronounced than when starch was used.
Carr's index (Y2). HPMC, starch, and silicon dioxide, when used for granulation, had significant effects (p < 0.01) on the compressibility index.
The negative sign of their coefficients indicates that they reduce the compressibility index values and thus yield agglomerates
with better flow. Guar gum and PEG also improved flow but to a lesser extent. Acacia had a significant effect on compressibility
index, but the positive sign of its coefficient indicated that it resulted in poor flow. These findings are similar to those
of Chukwu et. al., who reported the poor flow properties of granules prepared using acacia (21).