Filler-binder

Starches are added to processed meats—lunch meats, hot dogs, sausages, etc.—as fillers, binders, moisture retainers, and fat substitutes. They are added to soups, sauces, and gravies as thickeners. They are used in extruded cereals and snacks to hold the shape of the material. 

The use of hydroxypropyl cellulose (HPC), a binder, has increased in recent years [50a -50c], This material has been shown to reduce the incidence of capping when compared with MCC, PVP, and starch [50a], In addition, low substituted grades of HPC can also be used as a filler/ binder [50b]. 

AD Koparkar, LL Augsburger, RF Shangraw. Intrinsic dissolution rates of tablet filler-binders and their influence on the dissolution of drugs from tablet formulation. Pharm Res 7 80-86, 1990. 

In section 8.3 a study is described in which the SIR of crushing strength and the SIR of disintegration time are used to evaluate batches of tablets prepared for several combinations of filler-binders and disintegrants, with respect to their physical stability after storage under tropical conditions. 

The Storage to Initial Ratio of two tablet parameters crushing strength (S) and disintegration time (D) were measured for a combination of one filler-binder (a-lactose monohydrate) and one disintegrant (rice starch), at three concentration levels. 

Tablets were prepared either with an insoluble (dicalcium phosphate dihydrate), a soluble (6-lactose) or a moderately soluble filler-binder (a-lactose monohydrate). As a disintegrant four different starches (com, rice, potato and tapioca) were used. As a comparison the effect of two super-disintegrants (crospovidone and sodium starch glycolate) was studied. The disintegrants were added at two concentration levels. The compression load was adjusted in order to obtain tablets with comparable initial cmshing strengths.

Tablets from each combination of filler-binder and disintegrant were stored under different storage conditions. After storage the crushing strength and the disintegration time were measured. The influence of standardized storage temperature and standardized relative humidity as well as the standardized disintegrant concentration, on the physical tablet stability (SIR of crushing strength and of disintegration time) were calculated, as described in Section 8.2.

For each combination of filler-binder and disintegrant a 2 factorial design was used for the 3 variables studied disintegrant concentration (C), storage temperature (T) and storage relative humidity (R), at two levels each. Since the levels of each variable were not expressed in units of the same order of... 

INITIAL VALUES OF CRUSHING STRENGTH (So) AND DISINTEGRATION TIME (Do) OF TABLETS CONSISTING OF A FILLER-BINDER AND A DISINTEGRANT... 

Combination of filler-binder and disintegrant disintegrant concentration (% w/w) Sf(N) Df(N)... 

The influence of the adjustable variables (disintegrant concentration as well as storage temperature and relative humidity), on the SIR of crushing strength (SIR(S)) was calculated for each combination of disintegrant and filler-binder. This was expressed as in equation (10). 

Irrespective of the filler-binder used, in tablets prepared with crospovidone as a disintegrant, all three adjustable factors influenced the SIR of crushing strength. Also the interaction between the concentration and the relative humidity was significant (y0i3,siR(s) 0)-... 

Coprocessed excipients have been mainly used in DC tableting because of their better flow ability and compressibility, and the excipient formed is a filler-binder. The compressibility of several coprocessed excipients such as Cellactose (45), SMCC (42,44), and Ludipress (BASF AG, Ludwigshafen, Germany) (46) have been reported to be superior to the physical mixtures of their constituent excipients. While comparing the compressibility profile of SMCC with MCC in the presence of high compression forces, the former was found to retain the compaction properties,... 

Syntactic foams are less combustible than their chemically foamed counterparts for the same reason. A syntactic foam s fire resistance can be increased using modifiers and additives in much the same way as for ordinary plastics, the only additional precaution being that the filler—binder adhesion should not be impaired in the process. Specially compounded polyester resins have been used in the USSR to obtain syntactic foams, whose combustion times and mass losses are, respectively, 4-60 and 24 to 180 times lower than those of the unmodified plastic 155). 

However, some excipients have multiple functions. For example, microcrystalline cellulose can function as a filler, a binder, and a disintegrant. As seen in Table 7.3, a typical low-dose formulation could include more than 85% filler—binders. Thus, physical and chemical properties for these specialty excipients are extremely important in a low-dose formulation for manufacturability, product performance, and longterm stability. Because the poor physicomechanical properties of components are not altered during manufacture as they are in the wet or dry granulation process, critical material properties and their impact on product quality attributes should be well characterized and understood.23 Discussion in this section will focus on fillers-binders. For those requiring more information on excipients, several excellent books and review articles are available in the literature.24-27... 

There are many commercially available direct compression filler-binders. The most commonly used filler-binders include spray-dried lactose, mannitol, microcrystalline cellulose, pregelatinized starch, and dibasic calcium phosphate. Many factors affect the selection of a filler-binder for a direct compression tablet formulation. The most important requirements for a directly compressible filler-binder used in a low-dose formulation are listed below ... 

Certainly, not a single excipient meets all the optimum requirements. Therefore, it is common to use a combination of two filler-binders in order to obtain a formulation with excellent tableting properties. 

Lactose. Lactose, an animal-origin excipient, is the oldest and still one of most widely used direct compression filler-binders. Lactose is commercially available in various grades that differ in properties such as shape, particle size distribution, and flow characteristics. This permits the selection of the most suitable material for a particular application. Direct compression grades of lactose are available in three forms ... 

TABLE 7.4 Typical Physical Properties of Selected Lactose as Directly Compressible Filler-Binders... 

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