Tablet direct compression method

Ibrahim, Y. . E., and Olurinola, P. R. (1991), Comparitive microbiological contamination levels in wet granulation and direct compression methods of tablet production, Pharm. Acta Flelv., 66, 298. 

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... 

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. ... 

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. 

Bi YX, Sunada Y, Yonezawa Y, Danjo K. Evaluation of rapidly disintegrating tablets prepared by a direct compression method. Drug Dev Ind Pharm 1999 25(5) 571-581. 

Low-substituted hydroxypropyl cellulose is widely used in oral solid-dosage forms. It is primarily used in tableting as a disintegrant, and as a binder in wet granulation. It has been used in the preparation of rapidly disintegrating tablets produced by direct compression methods. In addition, low-substituted hydroxypropyl cellulose has been used to delay the release of drug from a tablet matrix. ... 

Tragacanth was used along with pectin in sustained released matrix tablets produced by direct compression method. They showed good release retardation exhibiting a non-Fickian diffusion behavior [61]. Addition of tragacanth in a topical formulation resulted in acceleration of skin wound healing [63]. 

Fourman GL, Cunningham DL, Gerteisen RL, Glasscock JF, Poska RP. Improved color uniformity in tablets made by the direct compression method a case study. Pharm Tech 1990 14 34-44. 

A. Khanum, D.S. Gayathri, Comparative evaluation of matrix tablet of diclofenac sodium employing wet granulation and direct compression method using blend of polymers. Res J Pharm and Technol, 1 (3), 265-269,2008. 

Direct compression method In this method, the drug is grounded and mixed with the matrix and a binder in a definite proportion in the presence of a volatile solvent. Next they are compressed into tablets under high pressure (2-3 tons/cm ) [66]. 

Direct compression method is the simplest and most economically viable method of tablet preparation. 

Direct Compression. This process is relatively simple and time saving. AH the ingredients are blended and then compressed into the final tablet. This is an excellent method, but encumbered by a number of problems. Not all substances can be compressed directly, necessitating a granulation step. Likewise, the flow properties of many blends of fine, particle-sized powders are not such as to ensure even filling of the die cavities of tablet presses. In addition, air entrapment can occur. 

The availabihty of spray-dried lactose, microcrystaUine cellulose, and other excipients allows for the use of granular rather than powdered phases. This eliminates some of the problems of particle segregation according to size (demixing) and even flow to the die. Direct compression eventually may be the preferred method of tablet preparation. 

Bindschaedler and Gurny [12] published an adaptation of the simplex technique to a TI-59 calculator and applied it successfully to a direct compression tablet of acetaminophen (paracetamol). Janeczek [13] applied the approach to a liquid system (a pharmaceutical solution) and was able to optimize physical stability. In a later article, again related to analytical techniques, Deming points out that when complete knowledge of the response is not initially available, the simplex method is probably the most appropriate type [14]. Although not presented here, there are sets of rules for the selection of the sequential vertices in the procedure, and the reader planning to carry out this type of procedure should consult appropriate references. 

Shallow convex tablets (jin) containing 300 mg HPMC K15M and 1% magnesium stearate were prepared by direct compression. Disintegration tests were performed in triplicate, using the BP 1988 method, in 600 ml of media at 37°C using discs. Tests were run for a maximum of 2 h. 

Buccoadhesive-controlled release tablets for delivery of nifedipine were prepared by direct compression of carboxymethyl cellulose (CMC) with carbomer (CP) and compared to those prepared with PVP, PVA, HPMC, and acacia by a modified tensiometry method in vitro. It was found that the adhesion force was significantly affected by the mixing ratio of CP CMC in the tablets. CMC is necessary for controlling the release rate, whereas CP is important in providing bioadhesion. The tablets containing 15% CMC and 35% CP were found to have optimum drug release rate and bioadhesion [81]. 

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. 

The first direct compression excipient, spray-dried lactose, was introduced in the early 1960s as a filler specifically designed for direct compression processes. Over many years, more direct compression API and excipients, especially diluents and binders, were developed. Since these are now commercially available, design of direct compression formulations is readily possible. However, despite the simplicity of the direct compression process, the pharmaceutical industry still produces most tablets by wet granulation methods.1... 

Theophylline tablets made by both direct compression and wet granulation have been assessed. There is almost no difference between direct compression and wet granulation methods (see Figures 12-14) under the following conditions appropriate formulation (sufficient level of HPMC in the tablet) and precise control of the wet granulation process. Direct compression using Metolose SR is recognized as a suitable process for matrix tablets. 

Due to the forces evolving during tableting the compressed material can warm up. The evolving temperatures can be measured with different methods. In each case only approximated measurements are possible since either the measurement was not performed directly inside the tablet or additives were necessary, which can alter measurement. 

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