The in vivo performance of a novel enteric double-coating technology designed to accelerate release in the proximal small intestine of humans was investigated. Tablet cores were coated with a double layer formulation consisting of an inner layer of EUDRAGIT L 30 D-55 neutralised to pH 6.0 in the presence of 10% citric acid, and an outer layer of standard EUDRAGIT L 30 D-55. A conventional single coating of EUDRAGIT L 30 D-55 was also applied to tablets for comparison purposes, with the identical coating formulation and thickness (5mg/cm(2)) as the outer layer of the double coating. Eight fasted volunteers received the double-coated and single-coated tablets in a two-way crossover study. The formulations were radiolabelled and followed by gamma scintigraphy; the disintegration times and positions were recorded. After leaving the stomach, tablets coated with the single-coating formulation showed a significant time delay before disintegration occurred in the mid to distal small intestine, with a mean disintegration time of 66 ± 22 min post gastric emptying. The double-coated tablets disintegrated earlier at 28 ± 6min post gastric emptying with consistent disintegration in the proximal small intestine. The accelerated in vivo disintegration of the double-coating system can overcome the limitations of conventional enteric coatings.
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