Preliminary applicability tests of different methacrylic acid copolymers, type C NF, particularly relevant to...

The intention of this study was to show under which conditions a film forming methacrylic acid copolymer coating excipient, corresponding to the requirements of pharmacopoeia, but obtained from different sources, can be substituted without severe problems. The mechanical properties of the film coats were investigated by dynamic-mechanical thermo-analysis (DMTA) experiments to determine with respect to the glass transition the storage modulus E', the loss modulus E'', and the loss factor tan delta. Further determinations concerned the surface tensions of the different coating dispersions. This attribute plays an important role in spreading, distribution and coalescence of the film forming preparations. Finally by a series of small experimental fluidized bed batches cores containing a model drug were coated with the different methacrylic acid copolymers. The resistance of these coated tablets in 0.1 N HC1 as well as their dissolution rates in artificial intestinal juice were tested. The coatings proved themselves so similar that in this case substitutions of products of different provenance are possible. The determinations of surface tension and the DMTA measurements seem to be useful and reliable preliminary applicability tests.