Tablet by wet granulation

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... 

Bandelin, F.J. Compressed tablets by wet granulation. In Pharmaceutical Dosage Forms Tablets, Lieberman, H.A., Lachman, L., Schwartz, J.B. Eds. Marcel Dekker, Inc. New York, 1989 I, 160-164. 

Figure 11 Factors affecting flow of a tableting mixture prepared by wet granulation.

When tablets are prepared by wet granulation, the standard deviation of the dissolution rates seems to be dependent on the grain size distribution (Fig. 3). Mean diameters of batches prepared... 

The tablets obtained by direct compression in a single punch machine (Frogerais) and those obtained by wet granulation had very similar values only the coefficient of variation differentiate these two processes. 

The first component, which expresses the curve shape, exhibits an opposition of the release profiles obtained by wet granulation and by direct compression. The wet granulation profile has a sigmoid aspect while the direct compression profiles, particularly those for the tablets obtained in rotary machine, are nearly linear. 

The plots of two components obtained from PCA and lfom discriminant analysis, revealed an opposition between tablets obtained by wet granulation and by direct compression. In fact, the principal component represents the curve shape of the dissolution profiles (P), which, in these two processes, were quite different. 

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