Results and discussion
The weight, diameter, and thickness ranges are shown in Table II. Tablet hardness increased in direct proportion to the amount
of pressure applied and in indirect proportion to the concentration of polymers. Hardness also varied according to the type
of polymers included. The percent friability was less than 0.5%. The data obtained are shown in Table II.
Table II: Physical characteristics of the metronidazole tablet.
The bulk density of the granules was between 0.322 and 0.788 g/cm3 , indicating their good packing capacity. The tapped density of the granules was between 0.375 and 0.866 g/cm3 , showing good flow characteristics. The Carr's index, Hausner's ratio, and angle of repose of the granules were within range,
thus indicating good flowability. Results are shown in Table III.
Table III: Flow properties of granules.
The 80-mg tablet formulations containing Methocel K15M CR showed significant water penetration (i.e., 17%) that enabled the
tablet to dissolve, whereas formulations containing HPC showed only 1–4% water penetration. The metronidazole formulation
containing Methocel K15M CR and Carbomer 934P had a floating lag time of less than 300 s. Formulations using HPC had no buoyancy
after 8 h. Formulations containing Methocel K15M CR had floating time of 4 h, and Carbomer 934P had a floating time of 8 h
(see Table I).
Tablets' floating capacity depends on the density of the system, the quantity of the gas-generating agents (i.e., NaHCO3 and citric acid), and the concentration of polymers. Table I shows the floating lag time of the tablets. The tablets formulated
with Methocel K15M CR and Carbomer 934P became buoyant after 5 min of contact with the dissolution medium, but the HPC-containing
tablets did not show any buoyancy after 8 h.