EMCOMPRESS^® & ANHYDROUS EMCOMPRESS^®

Low Elastic Recovery

The share of elastic recovery is minimal for calcium hydrogen phosphate dihydrate, while the share of elastic recovery for pregelatinized starch is almost four times as high. The elastic recovery of microcrystalline cellulose is about twice the value of calcium hydrogen phosphate dihydrate.

This means that calcium hydrogen phosphate dihydrate is nearly free of elastic recovery and tablets made from calcium hydrogen phosphate will not regain size after compression. Thus, such tablets show a lower tendency towards capping and lamination.

Low Lubricant Sensitivity

Lubricants are needed for the smooth ejection of tablets from the die. Within a tablet itself, lubricant is not needed; it even affects tablet hardness negatively. Wherever a lubricant is blended with other excipients, it forms a thin, slippery layer on the outside of the powder particles. If elastic or plastic particles are compressed, this layer impedes the cohesion between the individual particles, leading to low tablet hardness.

Brittle fragmenting materials, such as EMCOMPRESS^® prove very beneficial if lubrication sensitivity is an issue. During lubrication, their particle surfaces are covered with lubricant particles. During compression, however, the excipient particles are broken into many smaller particles with a huge number of new surfaces which are not covered by any lubricant. These surfaces free of lubricant can stick together very well and guarantee good tablet hardness – even at high lubricant concentrations.

Low Strain Rate Sensitivity

Brittle fracturing materials break into small pieces immediately after the application of compression force and develop their binding abilities immediately. In contrast, plastic deformation is dependent on the time of force application. Thus, increasing the tableting speed for a powder mixture containing mainly plastically deforming materials leads to a decrease in tablet hardness, while the mechanical strength of the tablet remains unchanged if mainly brittle materials are used. EMCOMPRESS^® -based formulations are, therefore, highly suited for scale-up to high speed production.

Flow Improvement

EMCOMPRESS^® DC grades improve powder due to their high bulk density, while microcrystalline cellulose exhibits outstanding compatibility. Using a combination of EMCOMPRESS^® DC grades and microcrystalline cellulose, flowability and tablet hardness can be adjusted to formulation needs.

Water of Crystallization and Stability

Both EMCOMPRESS^® ANHYDROUS and EMCOMPRESS^® bear loosely bound water on the particle surface which can be removed by simple heating (i.e. loss on drying; upper part of pic. 4). The difference between the two EMCOMPRESS^® products lies in the amount of water of crystallization. EMCOMPRESS^® (i.e. calcium hydrogen phosphate dihydrate) comprises water of crystallization, which is incorporated into the crystal structure. In contrast, EMCOMPRESS^® ANHYDROUS is free of any water of crystallization.

Water of crystallization is tightly bound in the DCP crystal lattice and cannot be removed easily. Nevertheless, elevated temperature and humidity may occasionally trigger the liberation of the water of crystallization. This unbound water is freely available for side reactions and can accelerate microbial growth and cause changes in powder flowability. In order to always be on the safe side, it is advisable to use  EMCOMPRESS^® ANHYDROUS for new developments. Anhydrous DCP is free of crystal water and bears absolutely no stability risks, while maintaining the functional benefits of DCP dihydrate.