Scintigraphic evaluation of the in vivo performance of dry-coated delayed-release tablets in humans.

We characterized the gastrointestinal (GI) transit and drug release characteristics of dry-coated delayed-release tablets under both prandial states in humans using a gamma scintigraphy approach. We also estimated the onset time of drug release from the dry-coated tablets after dissolution of the outer layer in a clinical study, and compared findings with those of in vitro release testing. The dry-coated tablets used in this study were composed of a core containing radiolabeled resin (111-Indium) and a gel forming outer layer made of polyethylene oxide and polyethylene glycol. The dry-coated tablets were administered to human subjects in the fasted and fed state (30 min after ingestion of a standard breakfast radiolabeled with 99m-Technetium). Gastric emptying time, small intestinal transit time, and onset of radioactivity release in the GI tract were estimated from scintigraphic imaging. Release characteristics of the radiolabel from the dry-coated tablets were also assessed in in vitro dissolution testing using a USP apparatus 2 (paddle). Ingestion of food affected the gastric emptying time of the dry-coated tablets but not small intestinal transit. Onset timing of the release of radioactivity from the core of two different formulas of dry-coated tablets was characterized. The onset timing of drug release in the fasted subjects was markedly similar to that in the in vitro dissolution testing at a paddle rate of 200 rpm.