a Laboratory of Pharmaceutical Engineering, Gifu Pharmaceutical University, 1-25-4 Daigaku-Nishi, Gifu 501-1196, Japan
b Pharmaceutical Technology Department, Sawai Pharmaceutical Co. Ltd, 12–34, Hiroshibacho, Suita-Shi, Osaka 564-0052, Japan
Before designing tablet formulations, it is important to understand the “Tableting Properties” of excipients and API (active pharmaceutical ingredient) powders. Those include “Compressibility”, “Compactability” and “Manufacturability”, which are difficult to evaluate quantitatively.
In this study, we evaluate the “Tableting Properties” using the Gamlen R series (formerly Gamlen Tablet Press – GTP-1). We confirmed that the instrument and plot are useful in designing formulations efficiently using a small amount of sample powders.
Many kinds of powders such as excipient, binder, disintegrating agent and lubricant, are used to develop a tablet formulation. To obtain a final tablet formulation efficiently and quickly, it is important to know the compression properties of each powder. Generally, the “Tableting Properties” of powders can be evaluated mainly in terms of “Compressibility” and “Compactability”.
“Compressibility” is measured from the changes in the bulk density of the powder bed when a powder is continuously compressed. “Compactability” relates to the binding force between particles that results from applying pressure, and is seen in the strength of the tablet. Powders with a high degree of plastic deformability result in large contact area between the particles in the tablet. Compaction generates particle contact efficiently, and so plastic deformability is a desirable property for good “Compactability” (Tesfai and Goran, 1999). Conversely, elastic recovery may be an undesirable property with respect to “Compactability”. It is not easy to evaluate the plasticity or elasticity of a single particle directly.
When a tablet formulation is designed, it is necessary to determine the types, grades, and amounts of additives to be added to the preparation. These selections and decisions are usually based on designers’ rules of thumb; formulation design is very rarely done with an understanding of the “Tableting Properties”. Problems from poorly developed products to production problems and defects in products after distribution. If “Tableting Properties” can be properly understood, it can lead to a formulation design without complications.
A wide variety of additives have been developed for the purposes of tablet manufacture and many additives are also being used during the direct compression method of tablet production. For example mannitol and lactose granulated by spray drying or fluid-bed granulation are examples of additives that may be used for direct compression products, and they generally have excellent “Compressibility” and “Compactability” (Ilic et al., 2009).
It is difficult to evaluate “Tableting Properties” quantitatively. Recently the “Gamlen R series” has been developed for measuring “Compressibility”, “Compactability” and “Manufacturability” in a single device. This instrument makes it possible to measure pressure and displacement in the compression process, as well as the friction during ejection and the breaking strength of the resulting tablets. The Gamlen R series accurately measures “Compressibility,” “Compactability” and “Manufacturability”.
Using the Gamlen R series, we measured the quantitative characteristics of typical pharmaceutical additives as a value of “Tableting Properties”. From the results, we have clarified the extent to which the “Tableting Properties” of additives for direct compression are superior.
In addition, we also measured the “Tableting Properties” value of microcrystalline cellulose, which has excellent “Compressibility” and “Compactability”, to check the applicability of the measurements of additives using the Gamlen R series (Zhang et al., 2003; Jivraj et al., 2000).
Furthermore, we investigated whether the Gamlen R series and our plot are useful to decide the types, grades and amounts of additives in tablet formulation design. A tablet with Losartan Potassium (LP) was chosen as a model preparation.
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