The blends containing MCC displayed different behavior. The bulk density remained constant with increasing pressure, and tapped
density increased slightly. The net result was a similar increase in Hausner ratio with increasing compactor pressure for
all formulations (see Figure 7).
Figure 7: Hausner ratio versus roll pressure.
Tablet testing. Figure 8 shows the tablet crushing strength of the tablets compacted from the granules. The tablet crushing strength is compared
with that of tablets made from powder blend equivalents of the precompacted granules (i.e., blends that were not roller compacted).
Figure 8: Tablet crushing strength of tablets compacted at 5, 10, 15 and 20 kN of the roller compacted granules.
The tablet crushing strength of the tablets increased with increasing compression forces. The granules prepared with 8.4 kN/cm
roller compactor pressure capped at compression forces above 10 kN. The tablet crushing strength is, however, more than sufficiently
high at this compaction force, as shown in the figure. It was not possible to produce tablets from the granules made at 10.5
kN/cm pressure because of the extremely poor flow of the granules. No attempt was made to improve this situation by adding,
for example, a flow agent. The friability of all tablets was low (all below 0.1%). Tablets containing MCC were slightly more
A decrease in tablet crushing strength occurred between powder blends containing MCC and the granules of the same blend. This
decrease between non-roller compacted blend and roller compacted granules was not seen with only anhydrous lactose. The tablet
crushing strengths of tablets with and without MCC were similar at equivalent compression forces.
The weight uniformity of the tablets (see Figure 9) is best when the blend contains MCC and at the lower roller compaction
pressures, which may be a result of granule-flow properties. Again, because tablets were not produced using the granules compacted
at 10 kN/cm (because of poor flowability), no results for these tablests are portrayed in the figure.
Figure 9: Weight uniformity relative standard deviation (RSD) of tablets compacted at 5, 10, 15, and 20 kN of the roller compacted
Anhydrous lactose and blends of anhydrous lactose and MCC are highly suitable for roller compaction. There are beneficial
and adverse effects of using blends of anhydrous lactose and MCC compared with anhydrous lactose alone. The addition of MCC
decreased the throughput of the roller compactor and increased the temperature of the ribbon. However, roller compaction could
be performed without the addition of a lubricant when a blend of anhydrous lactose and MCC was used. In addition, including
MCC slightly improved the tablet properties with lower tablet friabilities and improved tablet-weight uniformity. On balance,
the blend containing 35% MCC was optimal.
Increasing roller compactor pressure resulted in granules with wider particle-size distributions and worse flow. In these
studies, where milling was not optimized, a pressure of 4.2 kN provided the best balance between particle-size distibution,
flow, and tablet properties.
Sander van Gessel* is a product and business development manager, and Henk van Duinen is a research and development scientist, both at DMV-Fonterra Excipients, Nörten-Hardenberg, Germany, firstname.lastname@example.org
. Ivan Bogaerts is a test facility manager at The Fitzpatrick Company Europe, Sint Niklaas, Belgium.
*To whom all correspondence should be addressed.
1. S. Hein, J. Langridge, and K. Picker-Freyer, "Evaluation of Various Lactose Types and MCC for Roller Compaction," poster
presented at the 2007 AAPS Annual Meeting, San Diego, CA.