TABLETING
NEWTABLETING TOOL M
ost of the active pharmaceutical ingredients (APIs) are poorly compressible under applied compression pressure. It is very
important to understand the deformation properties of the material involved in the formulation to achieve strong tablets. T e Heckel method is widely used to analyse the macroscopic compression properties of the pharmaceutical materials. T is method has many limitations and it is very sensitive to experimental conditions.[1]
It
is also very prone to negative porosity issues at high compression pressure.[2] T e compression (CM) and
decompression modulus (DM) can be derived from force-displacement data generated using a compression simulator. T e compression- decompression moduli was used to propose a two dimensional ‘compression-decompression modulus classifi cation system’ (CDMCS).
DETERMINATION OF CDM Vivapur 101, Starch 1500, Emcompress and Tablettose 100 were selected to perform the analysis. T ese materials were compressed at three diff erent compression pressures (100, 150, 200 MPa) and three diff erent linear compression speeds (0.35, 0.55, 0.75 m/s) using a compression simulator (Presster). T e CM and DM can be determined
from the stress versus strain plot. A stress versus strain plot from 5-60 MPa compression pressure exhibited ‘bi-linear’ regions between 5-20 MPa and 20-60 MPa compression pressure (Fig. 1A). T is phenomenon indicates the material fragmentation at low pressure followed by deformation. T erefore, a plot of stress vs strain was analysed for two pressure regions; low (5-20 MPa) and mid (20-60 MPa); for the compression and decompression phase of each material.
MATERIAL’S MODULUS T e CM and DM can provide very important information about materials’
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deformation, fragmentation and elastic properties under applied compression pressure. T e rank order of CM and DM for all four model materials were observed as below:
Compression modulus (CM): Starch 1500 > Tablettose 100 > Emcompress > Vivapur 101 (5-20 MPa) Emcompress > Tablettose 100 > Starch 1500 > Vivapur 101 (20-60 MPa)
Decompression modulus (DM): Emcompress > Tablettose 100 > Vivapur 101 > Starch 1500 (5-20 MPa and 20-60 MPa)
T e rank of table mechanical strength (TMS) was observed as below:
Vivapur 101 > Emcompress ≥ Tablettose 100 > Starch 1500
Devang B. Patel, Vivek D. Patel, Robert Sedlock & Rahul V. Haware present a new way to investigate material deformation properties and predict tabletability
(A) Stress versus strain plot of Vivapur 101; (B) Compression modulus in compression phase of 5-20 MPa; (C) Decompression modulus in the decompression phase of 5-20 MPa
Vivapur 101 exhibits lower CM and DM, which results in higher TMS. Starch 1500 exhibits high CM under low compression regions, low CM under mid compression regions and low DM under low and mid compression regions, which results into low TMS. Emcompress exhibited a lower compression modulus and a higher decompression modulus than the Tablettose 100. T e higher moduli of fragmenting materials are due to their limited displacement or low strain in the loading and unloading of the compression pressure. Such stiff materials could mainly rely on the increasing bonding numbers by fragmentation into the smaller particles to provide a desired tablet strength.[3]
PROPOSED MATERIAL CLASSIFICATION SYSTEM Based on the data collected, the authors have proposed a new classifi cation system
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