Variation of composition of an enteric formulation based on Kollicoat MAE 30 D

Using a formulation described previously with Kollicoat MAE 30 D as the fil m-forming agent, the effect of variations in plasticizer type and quantity and talc concentration on the preparation and processing of spray-coating s uspensions and the properties of isolated films and film-coated caffeine ta blets prepared using them was investigated. In the preparation and processi ng of spray-coating suspensions, the plasticizers polyethylene glycol (PEG) 400, PEG1500, and TEC (triethyl citrate) tended to coagulate at all concen trations investigated, while Cremophor RH 40 coagulated above 10% (expresse d as a percentage of the mass of the film-forming agent used). Analogous pr eparations using propylene glycol (PG), PEG6000, and Lutrol F 68, on the ot her hand, were found to be stable at all concentrations. The instability wa s not caused by the Kollicoat MAE 30 D polymer dispersion as such, but by i nteractions between the finely dispersed pigments and other formulation ing redients. Equivalent nonpigmented preparations are stable and do not coagul ate. With all the plasticizers investigated, the minimum film-forming tempe rature (MFT) fell, albeit to differing degrees, as the amount of plasticize r increased. Similarly, the tensile strength of isolated films declined as plasticizer concentration increased, while the reverse was true as regards their elongation at break. Whereas neither the subsequent disintegration ti me nor the rate of release of active ingredient at pH 6.8 was significantly affected by the various plasticizer additives, the different film-coated t ablet formulations with a core containing a powerful disintegrant exhibited varying degrees of permeability to simulated gastric fluid. With PEG6000, permeability increased as the plasticizer concentration increased, while Lu trol F 68 provided an optimum barrier at 20%, and PG provided a good barrie r between 10% and 30%. No gastroresistance was obtained with TEC at 10%. On ly the best plasticizer formulations were used in the trials with different talc concentrations, namely, those formulations with 20% PEG6000, 20% Lutr ol F 68, 20% PG, and 10% PG. When talc was added, the MFT rose, reaching it s maximum at 13% talc (as a proportion of the film-forming agent). In the t est for gastroresistance, film-coated caffeine tablets without talc absorbe d distinctly more acid than those containing talc. Above 27% talc, the acid resistance improved only insignificantly. On the other hand, during this t est, only a maximum of 3% of the active ingredient was released into the ga stric juice. Of the variants investigated, the formulation with 20% PG and 27% talc performed best.