Tablet properties hardness

The compaction process can be described by a variety of force (or pressure)-displacement profiles, such as force versus time, force versus tablet porosity, and force versus tablet properties (hardness, friability, dissolution, etc.). The effect of compaction speed on a variety of tablet properties can also be studied. 

From these simple data on a single-stroke research press, a formulator can begin to generate relationships between tablet properties and the compressional forces used to compact them. Thus, one could plot tablet hardness as a function of compaction force or pressure (see Fig. 2). The same would be true for disintegration tune, thickness, a dissolution number, etc. In fact, any dependent variable (tablet property) can be related to the independent variable (compaction force.) It is important to remember that force is the parameter one can control and, therefore, the independent variable. 

Although there are many tablet properties to be evaluated, the most important to observe during the scale-up process are tablet hardness (or tensile strength) and tablet dissolution. The former could be affected significantly by press speed (if the... 

The type of drying technique (e.g., tray, fluid bed, microwave) required for the formulation needs to be determined and justified. The type of technique may be dependent on such factors as drug or formulation properties and equipment availability. Changing dryer techniques could affect such tablet properties as hardness, disintegration, dissolution, and stability. 

Tablet properties Tablet properties such as hardness, shape, and intaglia-tion (if required) are important to obtain a good film-coated tablet. The tablet needs to be hard enough to withstand the coating process. If tablet attrition occurs, the tablets will have a rough surface appearance. For tablet shape, a round tablet will be easier to coat than tablets will multiple sides or edges because of the uniformity of the surface. For intagli-ated tablets, the intagliation style and depth should be developed to prevent fill-in or chipping of the intagliation.

General instructions for the determination of tablet properties (e.g., hardness, disintegration, friability, dissolution profile, and stability) are contained in pharmacopeia [e.g., European Pharmacopoeia (Eur. Ph.) and U.S. Pharmacopeia (USP)]. 

Jerome et al. in the 1980s studied the effects of compactor adjustments on powder blend properties. His team s research showed that pressure applied by the movable roller is not a predominant factor. They found that the most important variable was the compactor feed screw in relation to the roll speed. They correlated improved tablet compression hardness to the feed screw speed in relation to the speed of the rolls.P ... 

The resulting measurement of a compression force is highly correlated with a variety of tablet properties. As compression increases, so does tablet hardness and weight (at constant thickness and true density), along with a force required to eject a tablet. Many variables affect the force of compression press settings, press speed, punch length variation, punch wear, and damage, formulation and excipient properties. 

Much of the current body of knowledge about compaction properties of pharmaceutical materials came from instrumented tablet presses. Many tablet properties, such as tensile strength (hardness) and porosity can be predicted from force profiles. Work of compaction (a scale-up parameter) can be obtained with proper instrumentation. Information about the plasticity of materials can be derived from force-time curves. ... 

In the batch represented in Fig. 6, a novice operator trainee has stopped the batch well before the peak of the derivative. This required a major adjustment of the tableting operation (force and speed) to produce tablets in an acceptable range of material properties (hardness and friability). 

Product quality due to variation of tablet properties (weight, hardness, etc.) or scg-regation/content uniformity concerns (discussed in another chapter but affected by flow). 

The properties given in Table 84 for povidone are also useful in the film-coating of tablets and hard gelatin capsules [281]. 

Table 176 shows how it was possible to considerably improve the tabletting properties of an antiacid tablet containing alginic acid, magnesium trisilicate, aluminium hydroxide and sodium hydrogen carbonate as the active principles by the addition of copovidone. The hardness was doubled and the friability reduced by half. 

One quality control application of near-IR spectroscopy is the nondestructive determination of tablet hardness. Near-IR prediction of tablet hardness has been used and investigated by Drennen for a number of years. In 1991, the first publication of the near-IR technique for this application appeared [26]. Ciurczak and Drennen published similar results in 1992 [60] and Drennen and Lodder in 1993 [61]. Results of a study presented at the 1994 annual meeting of the American Association of Pharmaceutical Scientists were published in a 1995 paper [62]. In that paper, Kirsch and Drennen identified the utility of the technique in the determination of multiple film-coated tablet properties, including tablet hardness. In a review paper regarding the use of near-IR in the analysis of solid dosage forms, Kirsch and Drennen discussed the historical aspects of near-IR prediction of tablet hardness [27]. 

Hardness, compatibility, and tabletting properties Tensile strength, flow, blending, and handling... 

Today, both MCC and PC fiber grades are widely used in tabletting. Depending on the composition of the formulation, one or the other cellulose product results in better hardness, friability, and disintegration values. However, the quantity of MCC required to yield comparable tablet properties is normally at least one-third higher than that of PC fibers. Since, because of a more economical production process, the cost of PC fibers is also lower than that of MCC, monetary advantages can be derived from using powdered cellulose. 

The objective was to formulate tablets, with a dissolution rate as constant as possible, a profile suitable for once daily dosing, and satisfactory physical properties (hardness, friability). 

---