Lactose placebo tablets

The impurity peak at RRT 3.4 was observed in all samples exposed to accelerated conditions. Structural identification of this peak could not be established since this component did not show any response in the mass spectral analysis. The presence of this peak in large amounts in both active and placebo tablets lead to the conclusion that the late eluting impurity observed at RRT 3.4 was indeed a degradation product of one or more of the excipient components present in the tablets. Because of the large amounts of this impurity in the samples, a study using the individual excipients was conducted to identify the source of this degradant. The study lead to the conclusion that the excipients exposed to accelerated conditions in powder form did not produce the degradation product. However, when the same excipients were compressed into pellets and exposed to the same conditions, lactose, microcrystaUine cellulose and croscarmellose sodium compacts showed the presence of the peak at RRT 3.4. 

The solubility of the tabletting mixture (drug and/or filler) in water also has a definite influence on the effectiveness of disintegrants. These are often more effective in insoluble mixtures. Thus, for instance, calcium phosphate placebo tablets with 4% crospovidone disintegrate significantly more quickly than corresponding tablets with lactose [441]. 

The hardness, friability, porosity and disintegration time of lactose and starch placebo tablets made with copovidone were directly related to the compression force used [458]. 

The meaning of the coefficients in these equations may be illustrated using the previously discussed data for the tableting of placebo mixtures (2), a-lactose monohydrate, potato starch and anhydrous a-lactose. We again consider the crushing strength of the tablets. 

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