Preparation and characterization of matrix tablets.To study the matrix-forming properties of the mucilage, tablets were prepared using diclofenac sodium as a model drug and
different ratios of dried mucilage powder (see Table I). Different batches of tablets were prepared (A1 to A4). The tablets containing 100 mg of diclofenac sodium were prepared by direct compression on a rotary tablet machine. The
batch size was 50 g. The turret was rotated at a fixed speed of 30 rpm. Tablets were prepared using a 10-station rotary tablet
machine (Minipress II, Karnavati Engineering, Ahmedabad, India) and evaluated for the following parameters: hardness, friability,
and uniformity of weight (22).
Table I: Formulation of diclofenac sodium matrix tablets by the direct-compression method.
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Hardness and friability test. Hardness and friability were determined using a Monsanto hardness tester and Roche friability tester, respectively.
Uniformity of weight. Twenty tablets were weighed individually, and the average weight was calculated.
Tablet swelling index. Tablets of equal weight were immersed in 50 mL of distilled water on a watch glass. At specific time intervals, tablets were
carefully removed from the watch glass and blotted with filter paper to remove the water present on their surface and weighed
accurately. The experiment was performed for 5 h. The swelling index was calculated using the following formula (23):
Radial and axial swelling of the tablet. The initial diameter and height of the tablet were measured, and the tablet was stored in distilled water. The increase in
diameter and height were measured at selected time intervals up to 5 h. The equilibrium degree of swelling (Q) was calculated from the radial and axial swelling ratio using the following equation:
in which Vt and Vo are the tablet volumes, Rt and Ro are the radii, and It and Io are the heights at time t and zero, respectively (24).
Dissolution-rate study.
In vitro drug-dissolution studies were conducted using the USP Type II apparatus (Model TDL-08, Electrolab India, Mumbai) at 50 rpm
in distilled water at 37 ± 0.5 °C. At specified intervals, 5-mL samples were withdrawn and replaced with fresh medium to keep
a constant volume. After appropriate dilution, the sample solutions were analyzed using a UV-visible spectrophotometer (Shimadzu,
Kyoto, Japan, Shimadzu-1700) at 276 nm.The amount of drug released was determined by reference to a calibration curve constructed
in the three sets of same dissolution media. The mean of the three determinations was used for the data analysis (25).
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