Characterization of a food-based enteric coating for capsules and its compatibility with an alternative sealing method

Efficiency of a new protein-based enteric coating for capsules was studied. Coating physical-chemical properties were compared to those obtained from a well-known methacrylate-based enteric coating (Eudragit®). Swelling in simulated gastric fluid (SGF) was 20 times higher than for Eudragit® films. Mechanical properties (elastic modulus, elongation and puncture strength at break) were comparable to those measured from a standard Eudragit® formulation.Pilot-scale coating trials were performed following three methods: using a standard spray-gun configuration, using a HPC-based seal-coat prior to enteric coating and using an “inverted” spray-gun configuration. The effect of these methods on capsules sealing and in vitro gastric performance was studied. In vitro tests were performed following the two USP official methods: disintegration and dissolution.Inverted gun configuration and HPC-sealing showed the highest sealing efficiency and the best in vitro performance. Capsules with a weight gain of 14-16% generally passed all USP tests (no disintegration evidence after 60 min in SGF; release below 10% after 2 h of experiments in SGF). However, in some cases, slight differences between results obtained from dissolution and disintegration tests were pointed out.This work demonstrates the potential of a protein-based enteric coating and underlines the importance of capsules sealing.

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