Tabletting, storage and measurements

The used tablet ingredients were a-lactose monohydrate (Ph.Eur grade, 100 mesh), rice starch (Ph.Eur. grade) and magnesium stearate (Ph.Eur. grade). Before use the magnesium stearate was sieved through a 210 im sieve. Prior to use, the materials were stored at 20 1 °C and 45 5% relative humidity (RH) for at least one week. 

The initial values of crushing strength (Sq) and disintegration time (Dq) of the nine batches of tablets (3 starch concentrations 3 compression loads) are given in Table 8.2. Just as was expected, the tablets prepared with a compression load of 157 MPa and low starch concentrations, show low values of crushing strength. Initially all tablets disintegrated within 1 minute. 

The influence of standardization of the variables is demonstrated for the model of the initial crushing strength (Sq), which can be expressed as a fimction of the compression load (F) and the starch concentration (C)  

Since the levels of the compression load and the starch concentration are not of the same order of magnitude, the effect of adjusting the concentration apparently is larger than the effect of adjusting the compression load. 

In order to allow for the comparison of the effect of adjusting the different variables, the values of the variables were standardized (Table 8.1). When the initial crushing strength (Sq) is expressed as a function of the standardized starch concentration (c) and the standardized compression load (f), the effect of the compression load and the starch concentration are in the same order  

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