Khishova O.M.
Pressing and firmness of tablets on the basis of finely powdered herbal substances
Abstract.
One of the important tasks that must be solved while developing the technology of tabletting finely powdered herbal substances is to investigate the firmness of the tablets made of these materials depending on the compaction pressure. The solution of this problem will allow to substantiate the conditions of the herbal materials pressing that provide for the manufacturing of pills of the required firmness and decomposition. The aim of this work was to study the dependence of the tablets firmness on the compaction pressure. The researches were conducted on the pattern of 8 standard finely powdered herbal substances, represented by different organs of plants, including powders of bark, grass, fruits, flowers, rhizomes and roots. The influence of bonding agents was investigated on the example of water starch gel and alcohol solution of polyvinylpyrrolidone that are used in pharmacy to increase the firmness of tablets. The obtained data have shown that the firmness of the tablets received on the basis of finely powdered herbal substances without the addition of bonding agents, is directly proportional to the logarithm of compaction pressure in the range from 50 to 200 MPa and is characterized by an individual (for each type of herbal material) angle of this functional dependence. Minimum compaction pressures, producing tablets of acceptable firmness range (>0,8 MN/m2) of the majority of the studied herbal substances are 100...200 MPa. The firmness of tablets prepared with the use of starch gel, is on a plateau with the pressure range of 100-150 MPa, not complying with the logarithmic-normal law as under the conditions of direct pressing. The effects of polyvinylpyrrolidone (PVP) alcohol solution on the firmness of tablets of finely powdered herbal substances appear to be stronger than those of starch gel. Alcoholic solution of PVP is an effective bonding component for most plant materials. It provides the possibility to make tablets of herbal powder substances that cannot be tabletted with acceptable firmness neither by direct pressing or by using starch gel.
Key words: tabletting, firmness, finely powdered herbal substances, tablets.
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