A combination of pH-sensitive caplet coatings may be an effective noninvasive strategy to deliver bioactive substances, nutrients, or their precursors to the colon.

We hypothesize that bacterially synthesized nutrients in the large intestine may significantly influence the nutritional status of humans and, specifically, that of the colonocytes. In vivo research with human subjects in this area has been extremely limited because of the absence of a noninvasive means to quantitatively deliver test doses of nutrients, or their precursors, to the colon. The purpose of this study was to design and test the effectiveness of a pH-dependent coating in delivering intact placebo caplets to the large intestine.