Tablet force

On tablet presses, it is widely used to detect the beginning of a turret revolution, to identify stations and to facilitate peak detection in tablet force control applications. 

Tablet Weight Control and Tablet Force Control...

Verain and coworkers (3) described the formulation of an effervescent paracetamol tablet dosed at 500 mg, containing saccharose and sorbitol as diluents. Other components were anhydrous citric acid, sodium or potassium bicarbonate, PVP, and sodium benzoate. The tablets were characterised by measurement of a number of responses, in particular the friability, the volume of carbon dioxide produced per tablet when it is put in water, and the time over which the tablet effervesced. The objective was to study the effects of 4 factors, the quantities of sorbitol and of citric acid per tablet, the nature of the bicarbonate (whether sodium or potassium bicarbonate), and the effect of different tableting forces on these responses. The... 

C. D. Ellison, B. J. Ennisb, M. L. Hamada, and R. C. Lyon, Measuring the Distribution of Density and Tabletting Force in Pharmaceutical Tablets by Chemical Imaging, J. Pharm. Biomed. Anal., 48,1 (2008). 

Tableting force granule porosity and this will lead to poorer dissolution as the granules do not break up easily and the penetration of dissolution medium is impeded...

Capsule Filling / Capsule Filling / Formation of capsules or tablets from Dissolution is dependent on the tableting force. 

Some presses are equipped with strain gauges at key points in the overall feed—compress—eject cycle. Thus, these measure compression and ejection forces. Tight specifications for punch lengths and weU-designed and prepared granulations have led to better control of variations in tablet weight. In fiiUy automated presses, weight variations are adjusted by computer. 

Osmotic Control. Several oral osmotic systems (OROS) have been developed by the Alza Corporation to allow controUed deHvery of highly water-soluble dmgs. The elementary osmotic pump (94) consists of an osmotic core containing dmg surrounded by a semi-permeable membrane having a laser-drilled deHvery orifice. The system looks like a conventional tablet, yet the outer layer allows only the diffusion of water into the core of the unit. The rate of water diffusion into the system is controUed by the membrane s permeabUity to water and by the osmotic activity of the core. Because the membrane does not expand as water is absorbed, the dmg solution must leave the interior of the tablet through the smaU orifice at the same rate that water enters by osmosis. The osmotic driving force is constant until aU of the dmg is dissolved thus, the osmotic system maintains a constant deHvery rate of dmg until the time of complete dissolution of the dmg. 

Mesalamine—Swallow tablets whole do not chew them. For the suppository, remove foil wrapper and immediately insert tiie pointed end into the rectum without using force. For tiie suspension form, instructions are included with the product. Shake well, remove the protective sheath from the applicator tip, and gently insert the tip into the rectum. Partially intact tablets may be found in the stool if this occurs, notify the primary health care provider. 

Initial Situation An experimental granulation technique is to be evaluated a sample of tablets of the hrst trial run is sent to the analytical laboratory for the standard batch analysis prescribed for this kind of product, including content uniformity (homogeneity of the drug substance on a tablet-to-tablet basis, see USP Section (905)" ), tablet dissolution, friability (abrassion resistance), hardness, and weight. The last two tests require little time and were therefore done first. (Note Hardness data is either given in [kg-force] or [N], with 1 kg = 9.81 Newton). 

Tablet. Summary of the main literature on the influence of shear forces on adherent cells ...

Pharmaceutical compressed tablets are prepared by placing an appropriate powder mix, or granulation, in a metal die on a tablet press. At the base of the die is a lower punch, and above the die is an upper punch. When the upper punch is forced down on the powder mix (single station press) or when the upper and lower... 

For most tablets, it is necessary to overcome the cohesive strength introduced into the mass by compression. It is therefore common practice to incorporate an excipient, called a disintegrant, which induces this process. Several types, acting by different mechanisms, may be distinguished (a) those that enhance the action of capillary forces in producing a rapid uptake of aqueous liquids, (b) those that swell on contact with water, (c) those that release gases to disrupt the tablet... 

Water Uptake. There is evidence to suggest that water uptake caused by capillary forces is the crucial factor in the disintegration process of many formulations. In such systems the pore structure of the tablet is of prime importance and any inherent hydrophobicity of the tablet mass will adversely affect it. Therefore, disintegrants in this group must be able to maintain a porous structure in the compressed tablet and show a low interfacial tension towards aqueous fluids. Rapid penetration by water throughout the entire tablet matrix to facilitate its breakup is thus achieved. Concentrations of disintegrant that ensure a continuous matrix of disintegrant are desirable and levels of between 5 and 20% are common. 

The major forces involved in the formation of a tablet compact are illustrated in Fig. 14 (a single-ended model) and are notated as follows FA represents the axial pressure, which is the force applied to the compact by the upper punch, FL is the force translated to the lower punch, and Fr is the force lost to the die wall. If one remembers that for every force there must be an equal and opposite force, the following relationship is obvious ... 

Fig. 14 Forces developed in the formation of a tablet compact., die wall FA, axial pressure applied by upper punch Fd, force lost to die wall Fr, radial die wall , tablet compact.

The force of tablet ejection from the die, Fr, is a function of both and the residual die wall force, RD WF, that exists after decompression. As the friction decreases, one will obviously see a corresponding drop in Fr. It is important to remember here that it is desirable for Fr to be as low as possible so that minimal damage is imparted to both the tablet and the tooling. 

ITMs provide a valuable service to all phases of tablet manufacture, from research to production and quality control [109 111]. As a research tool, ITMs allow in-depth study of the mechanism of tablet compaction by measuring the forces that develop during formation, ejection, and detachment of tablets. ITMs can also provide clues about how materials bond,... 

Measurement of the punch and die forces plus the relative displacement of the punches can provide raw data which, when suitably processed and interpreted, facilitate the evaluation of many tableting parameters. Many of the workers first involved in instrumenting tablet presses concentrated on deriving relationships between the applied force (FA) and the porosity (E) of the consolidating mass. 

When one plots force vs. displacement, the area under the curve thus represents work. In practice, the compression/decompression data take the form shown in Fig. 18. The area under the upward line represents the work done on the tableting mass during compaction, while that under the downward line arise from the fact work is done on the punch by the tablet as a result of the latter s elastic recovery on decompression. 

Fig. 18 A typical force-displacement curve. WF= work done overcoming die wall friction WD, work of elastic recovery Wp/, net work involved in tablet compact formation.

One should note that BC represents a highly elastic material as little plastic deformation or brittle fracture has occurred. Also, sharp differences between the slope CD and DE are indicative of weak, or failed, tablet structures. The RDWF estimated from these plots can provide a good indication of the ejection force. More detailed treatments of such studies are now in the open literature, to which the interested reader is referred [118-120],... 

Another approach to determining the contribution being made by each of the possible com-pression/decompression mechanisms involves monitoring the degree and rate of relaxation in tablets immediately after the point of maximum applied force has been reached. Once a powder bed exceeds a certain yield stress, it behaves as a fluid and exhibits plastic flow [121,122], Certain investigators [122] have studied plastic flow in terms of viscous and elastic elements and have derived the following equation ... 

Comparative reports in the literature confirm the necessity of employing some calibration procedure if results from testers are to be compared or reduced to actual units of force. This is particularly true where the information is being used to determine relationships between crushing strength to other tablet properties. 

Ishida et al. were some of the first investigators to propose a method for investigating the adhesive properties of tablets [151]. Their method involved placing a tablet onto a membrane under constant pressure for one minute and then measuring the force required to remove it. Most methods published since that time involve essentially the same principle, with variations in the type of membrane used and the... 

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