Tablet manufacture compression

The various preparation processes and technologies used in dmg product manufacture also can effect product safety, stabihty, and performance, eg, compression during tablet manufacture. The principal processes used in dosage form manufacture are as foUows (15). 

The tablet was introduced by Thomas Brockedon in 1843, and glyceryl trinitrate tablets appeared in the British Pharmacopoeia of 1885. Since that time, many variations have appeared but the basic process remains unchanged. There are three main methods of tablet manufacture, with choice depending on the dose and the drug s physical properties such as compressibility and flow (Figure 2.2). A drug with a large... 

Granulation particle size did not impact the release rate. In addition, tableting at various compression forces had no significant impact on the release rate of the tablets. This knowledge that variability in tablet manufacture resulted in a uniform sustained release dosage form provided an advantage for further process optimization and scale-up, as shown in Figure 23. 

Minimize the compression force required to achieve target tablet hardness Manufacturability Compaction simulator or tablet press Compression force... 

Therefore, for a given formulation (brittle vs ductile), a balance in the level of applied compaction force and roller gap width must be identified to control factors that influence tablet content uniformity (variability in sieve cut potency, sifting, and fluidization segregation) without sacrificing factors that influence manufacturability (compression force required to achieve target tablet hardness). 

Direct compression is a simpler alternative tablet manufacturing method. With direct compression, tablets are compressed directly from a powder mixture of an API and appropriate excipients. Like granulation methods, this approach is also based on the required flow, compressibility, and compactibility of a formulation. Direct compression offers both time and economic advantages by eliminating intermediate granulating and drying steps. 

Compared to wet granulation and roller compaction, the direct compression platform allows tablet manufacture with fewer unit operations, as listed in Table 7.1. The sections that follow discuss several advantages and disadvantages of using direct compression for tablet manufacture. 

TABLE 7.1 Comparative Unit Operations in Tablet Manufacture Using Wet Granulation, Roller Compaction, and Direct Compression... 

TABLE 7.11 Process Variables and Quality Attributes Using Direct Compression for Tablet Manufacture... 

EC is an inert, hydrophobic polymer that has been studied substantially for its application as a matrix-forming material in direct compression tablets. Direct compression is the preferred method of manufacture for producing tablets intended for immediate or sustained release. There have been reports on the compressibility and compatibility of EC [307-310] and on its use as a matrix-forming material in direct compression tablets for the delivery of soluble and poorly soluble drugs [311-316]. Tablet hardness [310,314,315], the particle size of the polymer [314,315,317], and the viscosity grade [313,314] were observed to directly affect the drug release rate. It was noted that tablet hardness affected the... 

Special attention should be given to the physical stability of the tablets manufactured by direct compression because some fillers/binders are known to soften or harden on storage. 

The compression event is the central stage of tablet production. Compression not only depends on the machine but to a great deal on the material properties of a tablet formulation. The principal stages of compression have been described above. Principally, from the machine manufacturing side two different possibilities of compression exist. Either the lower punch is closing the die from the bottom side and the upper punch moves downward for compression or both upper and lower punches move simultaneously toward each other and the powder is compressed from both sides. In the first case the surface hardness of the tablet is not the same on the upper... 

Tablets manufactured with OraSolv technology should contain an effervescence couple along with microparticles of drug within a rupturable coat. The tablets manufactured are compressed at a low hardness that promotes fast disintegration. The dosage forms need to be packaged in foil-foil aluminum blisters with a dome shape that impact physical protection and impermeability to moisture. This constitutes the PakSolv Techonology. ...

Tablets manufactured with DuraSolv technology contain a non-directly compressible filler and a lubricant. They may or may not contain effervescence, and the drug need not be taste masked. DuraSolv tablets are compressed at higher hardness compared to OraSolv that allows for packaging in bottles or push through blisters.

Both wet and dry granulation methods of tablet manufacture are complex multistage processes, but are necessary to convert the components of the formulation into a state that can be readily compressed into acceptable tablets. If, however, a major component of the formulation already possesses the necessary degree of fluidity and compressibility, granulation would be unnecessary. This is the basis of the direct compression method of tablet manufacture. ... 

The effect of the removal of the compressing force must now be considered. Elastic recovery will occur to a greater or lesser extent, which will result in a reduction in the strength of interparticulate bonds and an overall weakening of the tablet. It therefore follows that if a tablet is to be disrupted by elastic recovery, this is most likely to occur at its weakest point. This is just below the top surface, and is the phenomenon often encountered in tablet manufacture known as lamination or capping. With this explanation in mind, some effects associated with capping, and some causes and pragmatic solutions to the problem can now be explained. 

Armstrong, N.A. Time-dependent factors involved in powder compression and tablet manufacture. Int. J. Pharm. 1989, 49, 1-13. 

There are three methods of tablet manufacture designed to confer these essential attributes to a tablet formulation. Wet granulation and direct compression are the most important, with dry granulation (also known as precompression or slugging) used in some circumstances. Fig. 1 shows the processes of wet granulation and direct compression broken down into their constituent stages. 

If a major component of the formulation such as the diluent were to possess the necessary degrees of fluidity and compressibility, granulation would be unnecessary. This is the basis of the direct compression method of tablet manufacture. 

The perceived advantages of the direct compression process of tablet manufacture have given rise to a considerable body of literature. Between 1970 and... 

Fig. 1 Comparison of the (A) wet granulation and (B) direct compression processes of tablet manufacture.

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