Effect of lubricant on spreading of coating liquid on surface of tablets containing pancreatin.

The objective of this study was to evaluate the spreading of the coating liquid on different tablets containing pancreatin and microcrystalline cellulose. The effects of the ratio of the components, the presence of magnesium stearate and the blending circumstances were investigated. The contact angle of the liquids on the different tablets did not change linearly. For the mixture containing 50% pancreatin, the deviation of the measured value from the predicted one was more than 25%. This deterioration was also detected for mixtures containing 1% lubricant, but the extent was lower and was not modified by change of the mixing circumstances. This phenomenon was explained by the special microstructure of the surface of the tablet. This was predicted from the spreading coefficient, calculated from the surface free energy. The enrichment of pancreatin on the surface was preferred in binary mixtures. The spreading of magnesium stearate was most preferred for the powder mixture, and thus prediction of the properties of the tablet was easier for these mixtures. The extent of the effect of this excipient on the surface properties was very wide-ranging. The change in the spreading of the coating liquid was significant; however, the change in the work of friction was negligible.