Tableting indices

Hiestand Tableting Indices Likelihood of failure during decompression depends on the abihty of the material to relieve elastic-stress by plastic deformation without undergoing brittle fracture, and this is time dependent. Those which relieve stress rapidly are less... 

Table 13 Summary of Tableting Indices for Losula-zine HC1 and Furegrelate Na as a Solid Fraction of 0.9...

K. R. Middleton, G. E. Amidon, and E. L. Rowe, Tableting Indices and Tableting Behavior of Losulazine HC1 and Furegrelate Na, AAPS National Meeting, November 1986. 

The tableting indices methods, summarized in Table 1, require powder compacts that are prepared under carefully controlled conditions so that they are essentially free of flaws (4,7). These compacts are the samples used for indentation hardness and TS measurements. 

The punch pressure required to form a compact for tableting indices measurements is measured at the end of a long dwell time, typically 1.5 minutes, during which the punches remain in fixed positions and stress relaxation within the compact brings about a decay in the applied load. The reported pressure or CS is calculated from the relaxed force and it is dependent on the compact SF. A sample s CS at a standard SF, such as 0.85, can be interpreted to indicate the ease (i.e., the magnitude of the pressure) of forming compacts under standardized conditions. 

A powder compact s TS is the stress required to separate its constituent particles in tensile mode. This is measured for the tableting indices by transverse compression of the square compacts, using narrow platens. Stresses build within the sample until it fails in a tensile mode that is perpendicular to the direction of platen movement. Tablets that are manufactured on a traditional tablet press and that have high TS are considered hard and generally robust, and so this is a highly desired attribute for immediate release and other tablet types. 

Compacts for tableting indices determination for Avicel PH102, PH105, and PH302, as shown in Table 3, were prepared at a SF slightly lower (0.83-0.84) than the standard 0.85 in order to obtain a better measurement of indentation hardness. At SF of 0.85, these materials generally form very hard compacts such that indentations from pendulum impacts were extremely shallow and could not be confidently measured. Compacts prepared at slightly reduced SF were somewhat softer (lower... 

The range of compression pressures to prepare tableting indices compacts is shown in Table 3 with each considered moderate relative to other excipients such as lactose, mannitol, and calcium phosphate dibasic. Avicel PH302 required considerably less pressure than PH102 and PH105, and thus shows greater ease of compression. Their moderate compressibility indicates that a fairly substantial pressure was required to achieve the SF. The rank order of each excipient by the tableting indices mechanical properties is provided in Table 4. 

Note-. The solid fraction of DCP tableting indices compacts was less than 0.85, particularly for the Emcompress , CD Anhydrous and A-TAB grades . Abbreviation-. DCP, dicalcium phosphate. 

Williams RO, Sriwongjanya M, Barron MK. Compaction properties of microcrystalline cellulose using tableting indices. Drag Dev Ind Pharma 1997 23 695-704. 

Davar N, Shah R, Pope DG, Ausburger LL. A critical comparison of Hiestand s tabletting indices and traditional measures of compactibility to predict tabletting behavior. Pharma Res 1995 12 S168. 

Kuppuswamy R, Anderson SR, Hoag SW, Augsburger LL. Practical limitations of tableting indices. Pharma Dev Technol 2001 6 505-520. 

In each case, preconditioned material was placed in the hopper of an instrumented tablet machine and the performance of these two materials was compared at constant machine settings. The sample with 5.1% MC produced tablets that weighed slightly less (an effect on flow and bulk density), and as a result were exposed to lower compression force. However, the moist microcrystalline cellulose resulted in harder tablets, even though it had been exposed to lower compression force. The loci of points on the compression force versus hardness profile (Fig. 20) for the tablets indicate a different fundamental behavior for the two materials. 

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