Investigation of the effect of compaction speed on the compressional behavior of microcrystalline cellulose and starch

The main goal of this thesis was to examine the effect of the compaction speed on the compressional behavior of two excipients, microcrystalline cellulose and starch, using an eccentric and rotary presses.

First, the average weights of the tablets have changed due to the increasing speed, as the volume of die kept constant. They were grown, for eccentric press, or were reduced, for rotary press. Second, Compression force, needed to obtain tablets with similar strength, was increased during both tableting methods. The eccentric compaction was more stable regarding to the speed increase. Tablets were formed from all of the blends, with more or less success.

Additionally, as a result of force increase, resulted tablets were denser and less porous because of speed expansions during eccentric press. However, the blends containing 80% or more starch were not able to form tablets during the rotary press, because of the very poor die filling. Furthermore, blend containing 60% starch has shown very poor tabletability at speeds over 34 rounds per minute. The elastic recovery of tablets was very sensitive to the speed rises and to the concentrations of excipients during the eccentric press. Tablets have demonstrated an increase in their elastic recovery values in all cases.

However, the tablets with a higher concentrations of starch were significantly more sensitive to the increasing compaction velocity. According to these results, it can be concluded that the starch exhibit more elasticity than microcrystalline cellulose. The effect of magnesium stearate on tablets’ properties, such as the weight and the porosity, and compaction parameters, such as ejection force have also examined. As it expected from boundary lubricants, magnesium stearate has significantly reduced the ejection force values, required for removing the tablet from the die, compared with unlubricated tablets.

Additionally, tablets with lubricants were heavier and more porous. The compression force was adjusted according to the crushing strength values in rotary press. This was due to the fracture variations of such tablets during diametrical compression, which would give unreliable values of tensile strength. Moreover, elastic recovery, porosity, density values were not calculated for scored tablet, due to either the lack of punch displacement data from rotational machine or the relative complexity of measuring the volume of such tablets. If XI these values had been available for both machines, their comparison with respect to these parameters would be possible and the results of this thesis would have been more appropriate.

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