Tablets friability

Fig. 7 Optimum in vitro t50% release rate as a function of restrictions on tablet friability. (From Ref. 15.)...

Fig. 13 Contour plots for (a) disintegration time (b) tablet hardness (c) dissolution response (%) (d) tablet friability as a function of disintegrant level and compressional force. Dashed lines on ordinate denote limits of experimental range (—1.547 to + 1.547 eu see text for details).

Two additional experimental designs were carried out to optimize the formulation and granulation process (water addition time, granulating time, and addition of binder—dry versus in-solution— binder level, disintegrant level, and lubricant level). There was a trend toward improved compaction profiles and reduced friability with increased granulation time. It was also observed that the lubricant and disintegrant levels affected the friability of the tablets. The effect of the lubricant level on tablet friability is shown in Figure 20. The final formulation and process are summarized in Table 5. 

Figure 20 Effect of magnesium stearate level on tablet friability.

Bilayer compression force (kN) First-layer compression force (kN) Tablet cylindrical height (mm) Tablet hardness (N) Tablet friability (% 500 Drops)... 

Figure 29 Dependence of bilayered tablet friability on size.

Tablet friability Friability is an important characteristic on the tablets ability to withstand chipping, cracking, or dusting during the packaging operations and shipping. 

Press Speed (Tablets/h) Compression Force (kN) Tablet Hardness (N) Tablet Weight Variation (%RSD) Mean Tablet Friability at 4 rpm (%) Mean Tablet Friability at 15 rpm (%)... 

The integrity of the tablet formulation is assessed by rotating a predetermined number of tablets in a tablet friability tester. 

Tablet friability tester. Equipped with a specific rotating disc. Procedure...

During the compression of effervescent tablets, in-process tests are routinely run to monitor the process. These tests include controls of tablet weight, weight variation, thickness, crushing strength, disintegration, and appearance of the tablet. Friability and pH of the solution may be additionally tested. Electronic devices that monitor tablet weight are normally used. 

Non-contact laser profilometry has been used to obtain roughness parameters and surface fractal dimension (Ds) of erythromycin acistrate tablets It was expected that tablet surface fractal dimension (Ds) will depend on the compression force used for tabletting. However, tablet surface fractal dimension was found independent of the compression force ranging from 4 to 22 kN. Instead, a surface roughness parameter Rp, which is the maximum distance between the highest point and the average height of the surface profile, indicated the variation of tablet friability as a function of compression force (Fig. 7). 

Fig. 7 Variation of roughness parameter, Rp, and tablet friability with respect to compression force. (From Ref. ()...

Another scale-up approach, which is simple to understand, is to scale-up the compaction force based on the roller width. In this approach, once the desired tablet characteristics (i.e., tablet dissolution, granule flow, minimal tablet weigh variation, tablet hardness, and minimal tablet friability) are obtained, the ribbon compaction force is noted during processing from the known roll width. As the product is scaled up, the applied force is scaled up based on the roller width. Table 5 provides several examples of scale-up factors that can be used as a guide. This technique has been found to be successful, but may have some limitations as the entire scale-up relationship may not be linear. 

In tablet formulations, freshly prepared starch paste is used at a concentration of 5-25% w/w in tablet granulations as a binder. Selection of the quantity required in a given system is determined by optimization studies, using parameters such as granule friability, tablet friability, hardness, disintegration rate, and drug dissolution rate. 

Starch is one of the most commonly used tablet disintegrants at concentrations of 3-15% w/w. " However, unmodified starch does not compress well and tends to increase tablet friability and capping if used in high concentrations. In granulated formulations, about half the total starch content is included in the granulation mixture and the balance as part of the final blend with the dried granulation. Also, when used as a... 

Gordon MS. Process considerations in reducing tablet friability and their effect on in vitro dissolution. Drug Dev Ind Pharm 1994 20(1) 11-29. 

Chowhan ZT, Amaro AA. Optimization of tablet friability, maximum attainable crushing strength, weight variation and in vitro dissolution by estabhshing in-process variable controls. Drug Dev Ind Pharm 1988 14(4) 1079-1106. 

Chowhan ZT, Yang IC, Amaro AA, Chi LH. Effect of moisture and crushing strength on tablet friability and in vitro dissolution. J Pharm Sci 1982 71(12) 1371-1375. 

Chowhan Z, Chatteijee B. A method for establishing in process variable controls for optimizing tablet friability and in vitro dissolution. Int J Pharm Technol Prod Manuf 1984 5(2) 6-12. 

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